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The Recognition of
Ocular Disease.
A TREATISE FOR OPTICIANS.
By
JAMES FORREST, M.B., Ch.B. (Edin.)
Late Surgeon Eye and Ear Hospital, Croydon ; Chief Resident
Medical Officer at Central Lottdon Ophthalmic Hospital, St.
Mary's Hospital, Plaisto^v, E., and Throat Hospital, Golden
Square, If. ; Chief ^Clinical Assistant at The Central London
Eye Hospital, Gray's Inn Road, at Moorjields, City Road, and
at the Throat Hospital, Golden Square, W.
Published by
J. & H. TAYLOR,
Dioptric Works, Albion Street, Birmingham
and
J. & H. TAYLOR, (Lond.) LTD.,
3.3, KiRBY Street, Hatton Garden, London.
1911.
All Rights Reserved.
W. F. FRASEB
Box 1597
<^5
ap-i-
10^
PREFACE. L.t^^^y
The following pages have been written in the hope that
they may prove of service to those opticians who desire to obtain
a general knowledge of Kye Diseases. To render these more
intelligible a chapter on Elementary Physiology and Pathology
has been inserted.
In my endeavour to make this a concise and practical
treatise I have laid the greatest stress on those conditions which
the reader may meet with in the course of his practice, and
have excluded or dealt summarily with those he is unlikely to
encounter.
Typical illustrations of nearly all Diseases are given, and it is
hoped that these, together with the short descriptions, will enable
the student to avoid the many pitfalls with which the path of
the optician is strewn.
Finally I desire to express my deep sense of gratitude to
Mr. H. L. Taylor, not only for correcting the proofs, but also
for many valuable aids and suggestions which have both lightened
and added confidence to my labours.
J. F.
July, i^Ii.
f :290
CONTENTS.
PAGE
I. Elementary Physiology and Pathology ... ... i
II. Examination of the Eye ... .. ... 26
III. The Eyelids and Conjunctiva ... ... ... 35
IV. The Lachrymal Apparatus ... ... ... 52
V. The Cornea ... ... ... ... ... 55
VI. The Sclera ... ... ... ... ... 67
VII. The Iris and Ciliary Body ... ... ... 71
VIII. The Crystalline Lens ... ... ... ... 91
IX. The Vitreous Humor ... ... ... ... 102
X. Glaucoma ... ... ... ... ... 106
XI. The Choroid ... ... ... ... ... 113
XII. The Retina ... ... .. ... 119
XIII. The Optic Nerve ... ... ... ... 138
PHYSIOLOGY AND PATHOLOGY.
Chapter I.
PHYSIOLOGY.
To understand the action and working of the human body, which consists
of distinct but connected parts, it is first of all necessary to examine its
general structure. The adult body consists of a great number of diflFerent
parts, each having its own special work to do, and whose vitality is dependent
upon that of the body as a whole. These parts of the body are called "organs,"
and each does not only its own special work, but acts in harmony with all
other organs, which become grouped into what are termed " systems." Thus
the circulatory system includes the group of organs concerned in the circula-
tion of the blood, viz. : heart, arteries, veins, capillaries, etc. ; the
respiratory system is concerned in the act of breathing ; the digestive system
deals with the digestion of food ; the excretory system with the getting rid of
waste products ; the muscular system with movement ; the skeletal system
with the framework supporting the softer parts of the body ; and over and
above all, there is the nervous system (brain, spinal cord, and nerves), which
presides over, controls, and regulates the functions of the other systems.
An examination of an organ reveals the fact that it consists of
various textures termed " elementary tissues," just as a house is made
up of stone, wood, iron, mortar, and other substances.
The elementary tissues come under the four following headings:
1 Epithelial Tissues.
2 Connective Tissues.
3 Muscular Tissues.
4 Nervous Tissues.
These individual tissues, when examined microscopically, are seen to
consist of masses of minute cells united together by different amounts of
cementing material, just as the wall of a house is made up of bricks united
by cement. One tissue differs from another in the form and nature of its
cells, and in the varying amount of the intercellular substance.
The term cell was first used by botanists. In the popular sense of the
word a cell is a space surrounded by a wall, as a prison cell or the cell of a
honeycomb. Now a vegetable cell has a wall (composed of cellulose) surround-
ing it, but an animal cell differs from it in possessing no such wall, and is
merely a little naked lump of living material of jelly-like consistence, posses-
sing the power of movement, and to which the name " protoplasm " has been
2 PHYSIOLOGY AND PATHOLOGY.
given. Somewhere in the protoplasm of all cells is a roundish structure, more
solid than the rest of the protoplasm, called the nucleus, and frequently there
is also a clear space called a " vacuole." An animal cell, then, is a
mass of protoplasm, containing a nucleus. The simplest an'mals, like
amoebse, consist of one cell only ; the simplest plants, like bacteria, consist
of one cell only. These organisms are called unicellular, and in the progress
of their life history the cell divides into two, the two new cells separating
and becoming independent organisms, each repeating the process later on.
In higher animals and plants, though unicellular to start with, the division
and sub-division of the cells results not in separation but in combination,
though the different cells become highly differentiated, being modified
according to the special functions they have to perform. A living cell
possesses the power of assimilation, or ability to convert into protoplasm
the nutrient material or food which is ingested. It also has the power of
growth, which is a natural consequence of the power of assimilation, the
power of reproduction, and the power to excrete its waste materials ^the
products of its activities. Living material is in a continual state of unstable
chemical equilibrium, building itself up on the one hand, breaking down on
the other, the term used to indicate these intramolecular rearrangements
being metabolism.
The higher one ascends in the animal scale the more highly differentiated
do the various cells become, and we classify them (according to the function
they subserve) as bone cells, muscle cells, nerve cells, glandular cells, etc.
We will now briefly review the various kinds of tissues in the body.
Epithelial Tissue. This is the substance which forms the outer layer of
the skin of the body, and lines all the passages and cavities communicating
with the outside of the body, and also all closed tubes and cavities. Micro-
scopically it is seen to consist of variously shaped cells cemented together. Its
chief function is protective, and the greater the need for such protection the
harder and more horny is the tissue. The soft skin lining internal passages,
such as the nose, throat, air passages, conjunctiva, etc., is called " mucous
membrane," because some of the cells form a thin, viscid and slimy fluid
called mucus, which lubricates and so reduces the friction of surfaces.
Connective Tissue. This, as its name implies, unites different organs,
and also binds together the various parts of an organ. It is found in all
parts of the body, uniting the skin to the structures beneath, surrounding
and penetrating muscles, and forming a sheath for nerves, blood vessels, etc.
Under the microscope it is seen to consist of fibres of two kinds, with
cells, called connective tissue cells, around and between them.
One kind of fibre, arranged in bundles following a wavy course, is
inelastic, and is called "white connective tissue," whilst the other
kind consists of fine, straight, elastic fibres, and is called '' yellow
elastic tissue." Connective tissue fibres may be dense and closely
arranged, as in the sclera, or they may be open (forming a network) as
beneath the skin. In the latter case spaces called areolae, containing a clear
fluidj lymph, lie between the fibres. When these spaces are very large, as
those beneath the skin, the tissue is called "areolar tissue." When the
PHYSIOLOGY AND PATHOLOGY. 3
support required is of a firm character the connective tissue consists of
closely packed bundles of white fibrous tissue, the number of elastic fibres
present depending upon the amount of resilience required, as in ligaments
which bind bones together; but when the support needed is merely that of a
loose connection, as in the union of the skin to the subjacent structures, then
the bundles of fibrous tissue are widely separated by that serous fluid which
pervades and surrounds all tissue to a greater or less extent.
Connective tissue, highly magnified. The elastic fibres form an open network, the
white fibres being in wavy bundles. P Plasma cells. G Granule cell.
Bone, is a variety of connective tissue in which lime salts are deposited
between the fibres^ thus forming the most solid tissue in the body.
Blood is another variety of connective tissue, and represents the most
fluid tissue in the body, being a liquid structure holding in suspension
large numbers of solid particles called corpuscles The fluid part of the
blood is called plasma, or liquor sanguinis, and consists of 90 per cent,
water and 10 per cent, solids, the latter being chiefly proteids, with a little
fat, and inorganic salts. The corpuscles are of two kinds, red and white,
the latter being typical amoeboid animal cells. The red corpuscles are much
more numerous (about 450 times) than the white, averaging in man 5,000,000
per ,cubic millimetre, and they impart to the blood its red colour. When
Fi^. 2.
Blood under the microscope, showing red corpuscles ( R) in rouleaux and singly.
At IV are seen the white ones.
blood is shed it rapidly sets into a jelly and clots. This jelly contracts and
squeezes out of the clot a straw coloured fluid called serum, in which the
4 PHYSIOLOGY AND PATHOLOGY.
shrunken blood clot floats. The clot consists of threads of fibrin, in the
meshes of which the blood corpuscles become entangled. Thus blood serum
is plasma minus fibrin.
The red blood corpuscles in a freshly drawn film of blood arrange them-
selves in rouleaux, like piles of coin. They consist of a delicate, colourless
elastic envelope with coloured fluid contents, the latter being mainly a
solution of red substance called haemoglobin, which is a complex nitrogenous
compound containing iron. This hsemoglobin is of great importance, as it
forms a loose combination with oxygen, acting as the oxygen carrier of the
blood. It always contains some of this gas, but when saturated with oxygen
it becomes of a brighter red colour, and is termed oxyhsemoglobin, and when
deprived of it, reduced haemoglobin, which is of a darker red colour.
Hence arterial blood is bright red, and that in the veins dark red.
F^g' 3-
An amoeba, showing granular protoplasm, nucleus, and small vacuole. At 2 it is
throwing out a process to take in a particle of food ; at ^ it is dividing into two,
the nucleus alreadj' having divided ; at $ division is complete, each part having its
own nucleus.
The white corpuscles, often called leucocytes, are of irregular shape, and
microscopically they may be seen altering their form, as, like the amcebse,
they are .capable of spontaneous movement and division. They are true
cells, consisting of nucleated protoplasm, and they thus act like tiny living
creatures, creeping from place to place by putting out and drawing in
processes, taking up particles of foreign matter which they encounter on
their way. At times they make their way out through the thin walls of the
minute blood vessels into the surrounding tissue, especially when an
injurious foreign body intrudes into the tissue. These white corpuscles or
leucocytes are the scavengers of the system, and their function is to engulf
and remove all harmful bodies.
The blood supplies nutriment to cells and tissues of every organ of the
body, obtaining its nutritive matter from the digested food in the alimentary
canal. It further carries away from all parts waste material, which is after-
wards removed from it by excretory organs such as the kidneys. Another
function, performed by the red corpuscles, is to carry oxygen to the tissues,
which take it up and unite it with some other element or compound, result-
ing in the formation of substances of no further use to the body, and which
are termed waste products. The most abundant of these waste products is
carbonic acid gas. The tissues take oxygen from the blood, and return
it later as carbonic acid gas (COa).
The blood, during life, is in constant motion, leaving the heart by the
arteries, and returning to it by the veins.
PHYSIOLOGY AND PATHOLOGY. 5
The heart consists of four chambers^ two on either side, the right and
left auricles, and the right and left ventricles. Venous blood flows into the
right auricle, and then into the right ventricle, which pumps it into the
lungs via the pulmonary arteries. Here the venous blot)d gives up its
carbonic acid to the air in the lungs, and takes from it oxygen, the
blood and air being separated only by two exceedingly thin membranes,
tlirough which the gases can readily pass. The oxygenated (arterial) blood
flows back via the pulmonary veins to the left auricle, and passes into the left
ventricle, from which it is pumped into a large arterial blood vessel called
the aorta, and thence to all the arteries in the body. (See Fig. 6.)
As the aorta receives all the arterial blood from the left ventricle, it is,
of course, the largest artery in the body ; but, owing to the branches it gives
otf, it gradually diminishes in size, and finally divides into two main
branches, which in their turn further divide and sub-divide, each branch or
sub-division being smaller than the preceding artery. The larger arteries
have very thick walls, which are composed of three layers : (1) a thin internal
lining of epithelial cells, united together at their edges by a little cement;
(2) a middle muscular coat ; (3) a tough outer coat of connective tissue.
Their lumen, or internal diameter, varies from fin. in the aorta to 1/32 in.
in the smaller arteries. The smallest arteries gradually lose their outer and
Ftg. 4.
Magnified section of small artery A. with vein V. E, Cells of inner coat. M,
Muscular coat, with connective tissue beyond, the nuclei of connective tissiue
corpuscles being: seen.
middle coats, and later become so small that their diameter is only about
1 /3000th of an inch, there being left only the inner lining of endothelial
cells to form their exceedingly thin walls. These vessels are called capil-
laries, and it is whilst passing through them that the arterial blood gives
up its nutriment and oxygen to the surrounding tissue, and receives
carbonic acid gas and other products of oxidation in return. There is only
one thin membrane separating the blood from the surrounding tissue and
fluid, and this readily permits of diffusion. These capillaries gradually increase
in size, owing to many joining together, and hence the volume of blood
becomes greater. The wall now becomes strengthened by an additional coat,
and then the vessel is termed a vein. These veins unite together to form
6 PHYSIOLOGY AND PATHOLOGY.
larger ones, which in their turn unite again, until near the heart there are
only two large venous trunks, called vena? cavse, conducting the blood into
the right auricle. Thence the blood passes into the right ventricle, which
pumps it through the pulmonary arteries into the lungs. Here the dark
venous blood gives up its carbonic acid and takes in oxygen, returning to
the heart by the pulmonary veins. It passes into the left auricle and then
into the left ventricle, which again pumps it into the aorta. The orifices
connecting the vessels with the heart, and also the various compartments of
the heart with each other, are guarded by valves which allow of the flow of
the blood in one direction only. Veins also possess numerous valves for the
same purpose, but there are none in the arteries.
Blood pressure and the pulse. The aorta and the chief arteries have
so much elastic tissue in their walls, that they are really elastic tubes, and
this elasticity plays an important part in the circulation of the blood.
During life the arteries are always so full of bloi)d that their walls are tense,
and this pressure on the arterial walls is called the blood pressure. It is
shown by the spurting out of the blood when any large artery is cut, or by
placing a vertical tube in an artery, when, in tha case of the large arteries
near the heart, the blood will be forced up about five feet. Just as the blood
is pressing against the Avail, so is the latter, in virtue of the elastic
fibres it contains, pressing with equal force upon the contained blood,
squeezing the latter onwards towards the capillaries, as it is prevented from
going back into the heart by the closure of the valves. At each contraction
of the ventricle more blood is forced into the already distended aorta,
stretching it still more, and this extra expansion is reflected quickly as a
wave along all the ari>eries, constituting what is known as the pulse.
The pulse wave travels at the rate of 30 ft. per second, but does not, as
a rule, extend into the capillaries and veins, becoming extinguished by the
friction that the blood in its progress has to overcome, especially from the
greater total sectional area of the capillaries, and in these the jerky arterial
flow becomes converted into a steady and continuous one.
The left ventricle, in health, contracts about 72 times to the minute, as
is evidenced by the pulse rate, and during each contraction the arterial
blood pressure is, of course, raised. The blood pressure is greatest in the
arteries, less in the capillaries, and least in veins, but the onward flow in the
veins is arrested by muscular movement and respiration, valves in the veins
preventing the blood from flowing backwards. This pulse wave must not be
confused with the flow of blood, the latter being much slower, only about a
foot a second.
We have seen that the blood circulates in a system of tubes^ the
smallest, the capillaries, being so numerous as to form a close network in
all tissues. These capillaries have exceedingly thin walls, composed of only
a single layer of flattened cells united together at their edges. Through
these thin walls oxygen and part of the blood plasma (the fluid portion of
the blood) pass by diffusion into the surrounding tissue, thus providing
nutriment for the adjacent cells and fibres. This nutrient fluid,
PHYSIOLOGY AND PATHOLOGY. 7
oozing out of the capillaries and bathing the living tissues, is
called lymph. It is important to note that there is no actual contact
Highly magnified capillaries, showing walls ot single layer of nucleated epithelial
cells. C shows junctions of vessels.
between the blood and the tissues, but that the thin membrane separating
the two in the capillary vessels allows of the diflPusion of this lymph, which
acts the part of middleman between the blood and the tissues. The cells
and fibres of the tissue are thus bathed in lymph, and from it they take up
nutriment, whilst into it they excrete their waste products.
Lymph is a colourless fluid containing in solution, like the blood plasma,
proteids, carbohydrates and salts, though the proteids are somewhat less,
and the water more in proportion. It also contains some white corpuscles,
which have passed out of the blood capillaries, but few or no red ones.
Like blood plasma, it possesses the power of coagulating. As well as the
oxygen and nutritive material passing from capillaries to the lymph and
into the cells, there is also a passage, in the opposite direction, of carbonic
acid and waste material from the tissue cells to the lymph, thence into the
capillaries, and onwards into the veins to the lungs, etc. A certain quantity
of the lymph in the tissues does not find its way into the capillaries, but
returns to the blood stream in a roundabout way.
Lymphatic vessels. ^The excess of lymph from the blood, and the Avhite
blood cells present in it, which do not return into the blood capillaries, lie in
minute spaces between the cells of tissues, and these spaces are drained by
very small tubes which begin in the tissue, and are called lymphatic capil-
laries. These unite to form larger lymphatic vessels, and the lymph is
carried by these vessels to be emptied into the venous blood stream at only a
short distance from the latter's entrance into the heart. Lymphatic vessels
have valves in their interior like the veins, the free edges of which point
towards the heart, and the pressure, caused by muscular movements, drives
the lymph onwards towards that organ, the valves preventing any reflux.
The lymphatic vessels of the small intestine are designated lacteals,
because, besides imbibing tissue lymph, they absorb from the intestines the
emulsified fat of the food, and thus, after a meal, become filled m ith a white
milky looking fluid called chyle. The carbohydrates and the proteids of the
food, on the other hand, pass from the intestine directly into the bloo<l
stream through the walls of the blood capillaries.
8
PHYSIOLOGY AND PATHOLOGY.
The thoracic duct. All the lymphatic vessels from the lower limbs, the
lower part of the trunk, the intestines, and the left side of the body, discharge
into a large trunk vessel called the thoracic duct, which opens into the large
veins at the root of the neck on the left side. The lymphatics from the
right side of the head and neck, and from the right upper limb, open by a
common vessel into the veins on the right side of the neck.
Lymphatic glands. Both the lymphatic vessels and Jacteals from the
intestines pass, on their way to the thoracic duct, through small structures
termed lymphatic glands, which are really factories for the production of
white blood cells, and as the lymph percolates through the gland it carries
away with it many of these new colourless corpuscles. Lymph glands also
act as filters, the whit^ cells present seizing and destroying any foreign
body in the lymph, such as bacteria, dust particles, etc.
A short consideration of the whole vascular system, including blood,
lymph and chyle, assisted by a diagrammatic figure, will serve to render the
H ^
Fis'. 6.
Diagrammatic representation of the circulation.
subject more lucid. The arterial blood is shown shaded, the venous black,
and the lymphatics white arrows indicating the direction of the flow of
PHYSIOLOGY AND PATHOLOGY. 9
blood and Ijonph. Venous blood is collected from the capillaries of the
head and neck, H, by the upper vena cava, from the capillaries of the
extremities and trunk, shown at the bottom of the figure, by the lower vena
cava, and by these two great veins it is emptied into the right auricle, RA.
From the right auricle it flows into the right ventricle, RV, which propels it
into the lungs, P, through the pulmonary arteries, PA. Here the venous
blood gives up carbon dioxide and receives oxygen, becoming converted into
red arterial blood. From the capillaries of the lungs the purified blood
passes by four pulmonary veins represented by PV, into the left auricle,
LA, and from this into the left ventricle, LV. This then propels the blood
into the aorta. A, which gives off branches above to the head and neck, and
below to the stomach and intestines, S, to the liver, L, and to the smaller
arteries and capillaries of the other parts of the body. It will be seen that
the venous olood from the stomach and intestines, S, which is loaded with
nutriment derived from those organs, does not pass directly into the general
venous system, but first enters the liver, L, by the portal vein, V., uniting in
the liver with the pure blood of the hepatic artery, HA, the blood from
both these vessels leaving the liver by the hepatic vein, HV, to empty into
the lower vena cava. This part of the circulation is called the portal circu-
lation.
The diagram also represents the lymphatic system of vessels, the latter
being represented by E, arising in all the tissues and organs, and conveying
away lymph. Most of these vessels unite to form a large trunk, the thoracic
duct. The lymphatic vessels from the intestines are called lacteals, because,
during digestion, they convey with the lymph a milky fluid called chyle.
Blood, therefore, becomes venous in the systemic capillaries of all parts
by giving up, through the exuded lymph, some of its oxygen and nutrient
matter, and by taking from the tissues carbon dioxide and other waste
products. Blood becomes arterial in the capillaries of the lungs, where it
gives up some of its carbonic acid and water, by taking in oxygen again,
but venous blood contains a little oxygen, just as arterial blood contains a
little carbonic acid.
MusouLAB TissxJB. It is expedient to introduce here a few remarks on
the skeleton of the body, in order that the subsequent observation on muscle
may be the more easily understood. The whole of the bones of an animal in
their natural position constitute the skeleton, and in the human skeleton
there are more than two hundred bones, which are variously united together
80 as to form joints or articulations. The bones form the framework for the
body, supporting the soft parts, protecting important organs, and giving
attachment to the muscles of the body. The principal parts of the skeleton
are the spinal column, with the appended bony thorax (chest), the skull,
the bones of the arms, with the scapula (shoulder bone), and clavicle (collar
bone), to which each arm is connected above, and the bones of the legs, which
arp attached through the pelvis (hip bones) to the lower portion of the spinal
olumn. The various bones of the skeleton are kept together chiefly by
tough fibrous bands called ligaments, also by atmospheric pressure, and by
adhesions due to close contact, and their connection is made in various ways,
sometimes admitting of no movement between the two adjoining bones, at
lo PHYSIOLOGY AND PATHOLOGY.
others allowing more or less range and variety of movement. The union of
two contiguous bones^ together with the parts forming the connection, is
called a joint or articulation, and we divide these into immovable and
movable joints.
Section of a joint. The dotted line represents the sj novial membrane, the articular
surfaces being really in contact. P Periosteum. C Capsule. S Synovial fold.
J Joint cavitj. A Articular cartilage.
Bone, as Ave have previously observed, is a form of connective tissue, in
which inorganic material (chiefly calcium salts) is impregnated around and
between the fibres. It is covered by a fibrous membrane called
periosteum, containing many small blood vessels, which supply the outer
layers with nutriment. The inner part, called the marrow, is
much softer and less compact than the outer layers, and in the
larger bones blood vessels run through the outer compact layers to supply
nutrient material to the marroAv. Many of the smaller bones have no canal
with marroAv within, but only a thin, hard, compact layer beneath the
periosteum, with spongy tissue within.
The ends of bones Avhich are joined together to form a movable joint
are tipped Avith cartilage, the free surface of Avhich is smooth, and the ends
of the bones are also united by tough bands of fibrous tissue, called ligaments.
One of the ligaments forms a sort of loose bag all round the joint, and is
called the capsular ligament, or capsule. This ligament has a delicate lining,
the synovial membrane, which secretes a viscid fluid serving to lubricate the
heads of the bones, and to prevent friction.
The skeleton of the body, made up of numerous jointed bones and
cartilages, not only acts as a frameAvork, but the bones furnish points of
attachment for muscles, the latter being commonly called flesh. The
muscles, using the bones as levers, are the agents Avhich bring about move-
ment, and are of various shapes, the prominent ones being usually spindle
shaped, thicker in the middle than at the ends, where they terminate in one
or more white fibrous, inelastic cords termed tendons or sinews.
These must not be confused with ligaments, Avhich are the strong fibrous
bands binding parts together, esp>cially keeping the bones in place at the
joints. A muscle, of course, has two attachments, the more fixed or central
one is called the origin, and the more movable or peripheral attachment
PHYSIOLOGY AND PATHOLOGY. ii
the insertion. For instance^ the external ocular muscles are said to arise
from the more fixed bony orbit, and are inserted into the more movable
eyeball. The tendon, nearly always much more marked at the insertion
end of the muscle, blends with the periosteum of the bone. Muscular
Fig-- *
A Muscle, showing the tissue passing at each end into tendinous tissue. O Origin.
.S" Sheath. T Tendon of insertion.
tissue possesses the power of shortening or contraction, so initiating move-
ment. Muscles are divided physiologically into two great classes ; the
voluntary or striped, which are under the control of the will, and the
involuntary, or unstriped, as the iris and pupil, which are not, the latter
constituting only a very slight percentage of the muscular system, being
confined chiefly to the vascular system. The voluntary muscle, by the naked
eye, is seen to consist of small longitudinal bundles termed fasciculi, each
fasciculus being covered by a sheath of membrane, derived from the sheath
known as fascia, which invests the whole muscle. When a fasciculus is
examined microscopically it is seen to comprise a number of fine muscular
fibres running lengthwise, and consisting of a semi-fluid, contractile sub-
stance, termed muscle plasma, enclosed in a transparent elastic sheath
called the sarcolemma of the fibre. Just underneath this membrane can
be seen a nucleus. Such a fibre averages about 1 inch in length, but only
1/ 400th inch in diamet-er, and when seen under the microscope it shows an
alternate dim and light cross striation, hence the name striped muscular
fibre. The muscle fibres are joined together by delicate connective tissue
Figr. g.
A Muscle fibre torn across, the sarcolemma still joining the two parts. B Musck
fibre highly magnified, ^howing strtations and the elongated oval nuclei.
12 PHYSIOLOGY AND PATHOLOGY.
(perimysium internum) which also binds the fasciculi together (perimysium
externum), and this is continuous with the connective tissue sheath sur-
rounding the whole muscle. These various connective tissue membranes,
penetrating between muscles and their parts, convey the arteries, veins,
capillaries, and nerves. Capillaries do not enter the muscle fibre, the lymph
diffusing through the Barcolemma.
Unstriped, or plain muscular tissue, consists of fibres that do not show
the alternate light and dark striation, each fibre being a spindle-shaped
cell with an oval nucleus. Plain muscular fibres are never found attached
to bones, but are associated with other tissue, as in the Avails of the alimen-
tary canal (stomach and intestines), of blood vessels, etc. A muscle, on
being excited or stimulated, contracts by drawing its ends nearer together,
at the same time becoming harder and thicker in the middle, though it does
not become smaller in bulk. The amount of shortening varies, so that the
length of the muscle, when contracted, is from 65 per cent, to 85 per cent,
of what it was originally. Each single fibre forming the muscle becomes
shorter and thicker^ and as all of them contract at the same time, the muscle
contracts as a whole. Contraction may be brought about by dii'ect incita-
tion (electrical, mechanical, etc.), but ordinarily it is set up by a nervous
impulse. Besides that of form, muscle undergoes changes of temperature,
electrical condition, extensibility and elasticity. There are also chemical
changes, because, like other living tissues, muscle is taking oxygen and nutri-
ment from the blood, whose complex substances are constantly being oxidised
into simpler ones, as carbonic acid, etc. The contracted state of a muscle
can only endure a short time, this soon being followed by relaxation, and a
return to its normal length, but contraction can be excited again after a
very short interval of rest. The involuntary muscles contract and relax
much more slowly than the voluntary.
Though each muscle has a definite action, generally pulling along an
axis running between its two points of attachment, yet it must be borne in
mind that hardly any single muscle acts alone. Each muscle, as a rule,
forms one of a group, acting more or less in harmony with, and antagonised
by, other and opposite groups.
Nervous Tissue. This is the highest form of all tissue, all the actions
of life being regulated by one part or another of the nervous system. It
controls muscular action, regulates the processes of secretion in the various
glands, and determines the amount of blood supply to a part by acting on
the smaller arteries. The impressions of the outer world are also registered
by it, and it connects the various parts of the body with each other, co-
ordinating them into one harmonious whole. Its relatively great bulk and
its extreme complexity constitute two of the most distinctive structural
features in man. It is somewhat arbitrarily divided into two closely related
parts, the cerebro-spinal nervous system and the sympathetic nervous
system.
The cerebrospinal system consists of the brain, which occupies the
cranial cavity, and the spinal cord, lying in the spinal canal, which runs
PHYSIOLOGY AND PATHOLOGY.
13
through the centre of the vertebrae. These are continuous with each other,
and together constitute the cerebro-spinal axis. Attached to the brain
and spinal cord are the numerous nerves which connect the various parts of
the body with the central nervous system. There are twelve pairs of cranial
nerves, and thirty-one pairs of spinal nerves.
The brain and spinal cord are composed of two substances, presenting a
different colour to the eye, viz., white matter and grey matter. The former
consists chiefly of nerve fibres, the latter of nerve cells. The elements con-
stituting nervous tissue are nerve cells, nerve fibres, and a connective tissue
called neuroglia.
yerve cells are of different shapes, often irregular in form, and they
vary in size from l/400in. to l/4000in. The cell consists of a nucleated
mass of protoplasm, from which certain processes extend. According to the
number of processes they possess, they are called unipolar, bipolar, or multi-
polar. Most of these processes break up into branches called dendrons, but
one process is distinguished from the rest by non-branching. This un-
branched process is continuous with the central part or axis cylinder of a
nerve fibre, and is called the axon of the nerve cell. Each nerve cell, with
its axon, is an independent struct^^re, and the connection of one nerve cell
with another is made by the adjoining of the fine branches, although there is
no actual union of these.
Fig^. JO.
Multipolar cell from grey matter of spinal cord (highly inagtitfied). A Axon, with
medullary sheath M. C Cell body. A'' Nucleus, with nucleolus. D Branching
processes, which often interlace with those of other cells.
Nerve fibres. The cranial and spinal nerves appear to the naked eye
as white cords, which, on being teased out and microscopically examined, are
seen to consist of bundles of fine fibres held together by their connective
tissue, this passing not only between and around the bundles, but also around
the individual fibres. The nerve fibre is about 1/ 400th of an inch in
diameter, and appears microscopically to consist of three parts. :
14 PHYSIOLOGY AND PATHOLOGY.
(1) A central core of semi-solid matter called the axis cylinder, which
is the conducting portion of the fibre.
(2) A medullated sheath, fatty in nature, serving to insulate and
protect the axis cylinder. Sympathetic nerve fibres do not possess
this sheath, nor do the optic nerve fibres in the retina, except in
abnormal cases, when they appear ophthalmoscopically as a
glistening white area continuous with the disc.
(3) An outer sheath, called the neurilemma, with a nucleus lying
between it and the medullated sheath.
A nerve fibre is directly continuous by one extremity with a nerve cell,
whilst its opposite extremity breaks up into a number of ramifications,
ending freely in i-elation to another cell or to certain tissues of the body, as
a muscle fibre, etc., and hence the length of nerve fibres varies greatly.
Nerve fibres mereh' conduct the nervous impulse generated by the cell,
and so we divide them into two sets. Firstly, there are afferent fibres, which
conduct the impulse of impressions from the peripheral organs to the brain,
giving rise generally to a sensation of heat, light, sound, etc., and hence
often called sensory nerves. Secondly, there are efferent fibres, which con-
duct the impulse from the central nervous system to the muscles, glands,
etc., and are called motor nerves. Nervous impulses are conducted nor-
mally in only one direction ; in efferent nerves from, in afferent nerves to,
the nerve centre. When a nerve fibre is divided, that part cut off from the
cell degenej-ates, but later the fibre commences to grow from the other cut
end.
The nature of the nerve impulse is not known, but it is accompanietl by
electrical changes in the nerve fibre, and the velocity of the impulse is
estimated at about 100 feet per second.
The hrain is enclosed in the skull, Avhich is a bony box of many pieces,
fitted together by sutures. Besides this bony case the brain is invested by
three membranes, firstly, a tough one called the dura mater, which lines the
cranial bones and forms its outer covering, closely investing the brain
itself, and dipping down into all its furrows. The innermost is a more
delicate vascular membrane, called the pia mater, which largely supplies the
brain with nourishment. Between the two is another called the arachnoid,
large lymph spaces also existing between pia and dura mater and the arach-
noid.
The brain is an exceedingly complicated structure, and only a bare
outline of it will be given here. At the lowest part, continuing the spinal
cord upwards is the medulla oblongata; next comes the pons Varolii, or
bridge which connects the cerebellum or small brain with the cerebrum or
large brain. Through the brain runs a cavity filled with fluid and lined by
epithelium. This is continuous with the central canal in the spinal cord, and
also with the lymph spaces between the membranes of the brain, and
through these Avith the lymph spaces in the nerve sheaths. Any
increase of pressure wnthin the brain is manifested in the nerve sheaths, as is
evidenced by the appearance of choked discs (see Chap. XIII.) in brain
PHYSIOLOGY AND PATHOLOGY.
^5
tumor. The surface of the brain is convoluted, and fissures also run
through part of it.
Fig. II.
Plan, in outline, of the human brain as seen from the right side, the parts being
separated from one another more than is natural, in order to show their connections
plain!)'. A The cerebral hemisphere, showing fissures and convolutions. B Cere-
bellum, which is connected with the cerebral hemisphere by the peduncle. C Pons
varolii. D Medulla oblongata, which is continuous below with the spinal cord.
Continuous with the lower portion of the brain (the medulla oblongata)
is the spinal cord, which lies in the canal between the vertebra;. The spinal
cord consists of a central mass of grey nerve cells, the motor cells being
stationed anteriorly and the sensory ones posteriorly. Outside the grey cells
are placed numerous afferent and efferent white conducting nerve fibres.
Sensory nerve fibres arise from the posterior grey cells, and motor fibres
from the anterior grey cells. Outside the cord they join to form a single
mixed nerve.
Sensations that arise on the skin or extremities of the body muscles are
conducted by the afferent nerve fibres to the spinal cord, and on through the
medulla, in order to reach the cerebral hemispheres, where alone they are
interpreted. Also voluntary impulses pass from the cerebral hemisphere.*
through the medulla and cord, to reach the motor or efferent fibres that put
in action the muscles, glands, etc. Sensations from the face and head pass
into the cranial nerves, which pierce the skull in order to enter the brain
directly, and the motor fibres pass out in the same direction.
Both spinal and cranial impulses are appreciated in the other side of
the brain from that of the body from which they emanate, as all the nerve
fibres of one side of the body cross over to reach the other side of the brain,
and so injury of one side of the brain produces paralysis and loss of sensa-
tion in the opposite side of the body.
i6
PHYSIOLOGY AND PATHOLOGY.
Fio^. 12.
Diagrammatic transverse sections of the spinal cord.
A, showng a small portion of cord, (i) Anterior fissure between the two sides
OH the one of which the anterior grey root is shown, with motor fibres (5) arising
from it. (2) Posterior fissure to one side of which is the posterior grey root, with
sensory fibres (6) arising from it. (7) Mixed nerve, with sensory and motor fibres.
B showing a thin section of cord. The darker coloured central area represents the
grey cells, and the lighter coloured peripheral area the conducting aflferent and
efferent fibres. The numbers are as in A, (3) showing the anterior grey root, and
(4) the posterior grey root.
Befiex action. The spinal cord not only acts as a conductor of impres-
sions and impulses, but it also has reflex functions. It conducts motor
impulses from the brain to the muscles, and also sensory impressions to the
Fig- '3-
Diagram illustrating reflex action of spinal cord. S A sensory surface from which
an impulse passes by a sensory nerve to the spinal cord by the posterior root of
a spinal nerve. At P the nerve fibre breaks up and transmits the impulse to a
nerve cell A in the anterior horn of grey matter ; from A a motor impulse passes
outwards along a motor nerve to the muscle M. Sometimes an impulse passes on
to the other side of the cord, and then to a muscle M on the other side of the
body. When the brain is concerned in an action, the passage of the impulse to
that organ is indicated by the dotted line C, and the passage of an impulse from
that organ by the dotted line X.
PHYSIOLOGY AND PATHOLOGY. 17
brain ; and when it is crushed or injured those impressions commencing from
below the injured part cannot be transmitted to the brain ; yet by tickling
that part unconscious movements take place in it, and these are called
reflex. Movements which arise from sensory impulses and are carried out
without consciousness are also reflex movements. In the case of an injury
to the spinal cord in the middle of the back, tickling of the feet will produce
a reflex movement of the toes, as the tickling sensation passes along the
afferent nerve fibres to the posterior (back) part of the central portion of the
spinal cord, in which the sensory cells are situated. They cannot pass up
to the brain, owing to the injured cord, but the impression passes on to the
motor cells in the front part of the cord, and from there an impulse is
transmitted to the muscles of the feet through the efferent nerve fibres.
The simplest mechanism or structures necessary for a reflex act are (a) a
sensory surface, (h) a sensory or afferent nerve, (c) a nerve cell or centre,
(d) a motor or efferent nerve, (e) a muscle or gland.
The cerebral hemispheres (brain proper), especially the nerve cells in the
grey matter on the outside of the brain, are the seat of conscious sensations,
of perceptions, of intelligence, and of will. The lower parts of the brain are
the seat for the subconscious, automatic, yet vital processes, of respiration
and circulation, and also for many complex reflex actions, but consciousness,
memory and judgment are stationed in the cerebral hemispheres alone.
Chemical Composition of the Body. All substances are divided by
chemists into elements and compounds, the former representing simple or
indecomposable substances, and the latter compound ones, formed by the
chemical union of two or more elements.
The elements found in the body are oxygen, nitrogen, hydrogen, carbon,
sulphur, phosphorus, chlorine, sodium, potassium, calcium, magnesium, iron,
manganese, silicon, fluorine and lithium. The first three occur both free
and in combination, whilst the remainder are only present in compounds.
Oxygen (O) is an invisible gas that forms about one-fifth part of the
atmosphere by volume. It supports combustion, and is absolutely necessary
for animal life. It occurs free in the air passages of the lungs, and in
the blood it forms a loose combination with the haemoglobin of the red blood
corpuscles, the latter giving up the oxygen to the tissues.
Nitrogen (N) is an invisible, inert gas forming about four-fifths of the
atmosphere by volume. It occurs free in the air passages of the lungs, and
is dissolved to a slight extent in the blood. In combination with other
elements it forms the greater number of the substances of the body, many
of these compounds being of very great importance.
Hydrogen (H) is a very light, invisible and combustible gas. A little
free hydrogen is occasionally found in the intestines, arising from the
fermentation of certain foods. In combination with other elements it is
present in many compounds of the body.
Carbon (C) is a solid element existing in a variety of forms. Blacklead
and diamonds are natural conditions of the element, whilst charcoal is an
1 8 PHYSIOLOGY AND PATHOLOGY.
artificial form. When carbon burns it unites with the oxygen of the air to
form carbonic acid gas (CO2). Carbon exists in a combined form in most
animal and vegetable substances^ and the oxidation or burning of these
results in the formation of carbon dioxide (CO2) as one of the products.
Carbon does not exist free in the body.
Chemical compounds of the body. These are divided into organic and
inorganic compounds. Every separate living being, animal or vegetable,
is sometimes termed an organism, and the various substances built up or
produced by organisms which contained carbon were called organic sub-
stances, but as they can now be pi'oduced artificially we include in that term
all carbon compounds, however produced, as fats, sugars, starches, and pro-
teids. Substances obtained from the earth, that is, from the mineral
kingdom, are called inorganic compounds, as clay, common salt, limestone,
water, etc.
Plants, like animals, consist of living cells that are constantly building
up living matter out of the food supplied to them, which in the case of
plants consists of the simple inorganic substances found in the soil, and of
the carbon dioxide in the air, from which they obtain the carbon they
require. So plants live on simple inorganic materials obtained either from
the soil or the air, and then convert them into those complex organic sub-
stances which form their tissues. On the other hand, man and other animals
cannot convert inorganic materials, except water, into the living substances
of the body, and so animals must feed on the organic substances formed by
plants or supplied by the tissues of other animals that have lived on plants.
The chief inorganic compounds found in the human body are Avater, carbon
dioxide, sodium chloride and calcium carbonate and phosphate.
Water (H.^O) is a compound of the two elementary gases, hydrogen and
oxygen. It is present in all the tissues, and forms two-thirds of the body
weight. Though a little is produced in the body, yet it is nearly all derived
from food and drink. The water acts as a solvent for the nutrient matter,
makes certain tissues soft and flexible, and assists processes of secretion
and excretion. It also serves for the regulation of the body heat, by
evaporation from the lungs and skin.
Carbon dioxide (COj) commonly called carbonic acid gas, is formed
continuously in the body by the oxidation of carbon, and so is present in all
tissues, including blood, from which it is secreted in the lungs.
Hydrochloric acid (HCl) is a compound of hydrogen and chlorine, and
exists in small quantities in the stomach, being produced by the cells lining
that organ. It is of great service in digestion.
Sodium chloride (NaCl) is ordinary common salt, and exists in the blood
and many other liquids of the body.
Calcium carbonate and phosphate are found chiefly in bone. Many
other inorganic salts exist in the body, but only in very small quantities.
AVhen a body is cremated various compound gases, chiefly carbonic acid,
ammonia and watery vapour, are formed and escape into the atmosphere,
whilst the ash which remains is composed chiefly of the incombustible, inor-
ganic salts.
PHYSIOLOGY AND PATHOLOGY. 19
The organic compounds of the body belong, for the most part, to
three great groups- -proteids, carbohydrates, and fats. The proteids
are complex nitrogenous bodies containing carbon, hydrogen, oxygen,
nitrogen and sulphur. The varieties of proteids are many, but they have
one point in common, viz., that they contain nitrogen, and are the only
class of food which do so. Tissues require nitrogen for growth and repara-
tive processes, and hence proteids are often called tissue builders. They can
also be used for fuel, being oxidised to produce H^O, carbonic acid and
urea, though the chief fuel ingredients of food are carbohydrates and fats.
Proteids are most abundant in the lean meat of all animals, the Avhite of an
egg, and in such vegetables as peas and beans.
Carbohydrates are organic compounds of carbon, hydrogen and ogygen
in which there is always the same proportion of hydrogen and oxygen as in
water, \iz., two atoms of hydrogen to one of oxygen. The substances known
as starches and sugars belong to the carbohydrates, which in the body become
oxidised, being converted into carbon dioxide and water, such changes
generating heat. Fats are also organic compounds containing carbon,
hydrogen and oxygen, but the oxygen is smaller in proportion to the hydro-
gen than in the carbohydrates. Fats and- oils are found in the tissues of
some animals, in milk and in certain seeds. The oxidation of fats is one of
the chief sources of heat to the body, a given weight of fat producing more
heat energy than the same weight of any other food stuff,
Proteids and carbohydrates are converted into soluble bodies by the
stomach and small intestines, and then pass into the capillaries of the
portal circulation, which convey them to the liver. Here a percentage of
the carbohydrates is arrested and stored up in the liver cells, whilst the
remainder undergoes combustion in the tissues, as likewise does most of the
proteid material. The chief waste product of the latter is called urea,
excreted principally by the kidneys.
Fats are absorbed into the intestinal lymphatics, called lacteals, which
carry them into the blood stream, and the latter conveys them to the tissues,
where they undergo slow oxidation, producing carbon dioxide and water.
The living body may be regarded as a machine, the fuel being the food
which undergoes oxidation, producing heat and the energy for muscular and
nervous labour. The food is not only an energy producer, but it also fur-
nishes the materials for the repair of the waste that is continually going on,
and during the early period of life it increases the size of the body and its
organs. The body is not only a self repairing, but also a self constructing
machine. It loses on an average about eight pounds per day in weight,
made up as follows
Water. Solids in solution. Carbon dioxide gas.
From the lungs .. .. laoz. 36 ounces.
From the skin 34 < J oz. salts. Small quantity in solution.
From the kidneys 5<> ' 'I " urea.
I II salts. i 11 .1
In this daily loss the chief elements are carbon, nitrogen, hydrogen and
oxygen. The carbon is lost chiefly in the carbon dioxide given off by the
lungs, and the nitrogen disappears in the area dissolved in the urine. There
20 PHYSIOLOGY AND PATHOLOGY.
are fifteen parts of carbon given off to one of nitrogen, about eight ounces
of the former to half an ounce of the latter. It is evident that if a man is to
keep his weight and to continue warm and active, fresh material must be
taken into his system in order to repair the waste, and to restore, by oxida-
tion, heat and other energy expended, whilst in the young body provision
must be made for growth.
PATHOLOGY.
Pathology is the study of the body in disease, but all pathological
changes are merely modified physiological ones, there being no essential
difference between the two. Thus, we have seen that serous effusion from
the capillaries into the tissues is an ordinary process of healthy nutrition,
but that serum, in excess, causes dropsy. The exit of white corpuscles from
the capillaries into the plasma is also a normal process, but white corpuscles
in excess become the products of inflammation and suppuration (formation
of pus). These gradations show how insidiously healthy processes pass into
diseased ones.
Inflammation. ^When a foreign body, either of a chemical or physical
nature, is introduced into the tissues, certain changes are manifested,
which represent the reaction of the system, or parts of it, against the
injurious effects of irritants, whereby nature endeavours to destroy,
counteract, or throw out what is noxious, and also strives to repair what has
been injured, and to restore that which has been destroyed. These processes
are called an inflammation, a beneficent action representing nature's efforts
to expel or render innocuous foreign bodies.
The white corpuscles are the cells which chiefly attack and remove
foreign bodies, and hence they are called the scavengers of the body, but
their activity is largely dependent upon the presence or otherwise of certain
complex chemical bodies in the blood plasma.
When an irritant is introduced into a tissue the neighbouring blood
vessels dilate, so bringing an increased number of white blood corpuscles
and serum into the area. The former are also produced in much greater
quantities, and they, together with the serum, pass out of the walls of the
capillaries into the tissue much more freely than usual, resulting in red-
ness and swelling of the latter.
An inflammation of a tissue is accompanied by the following signs :
Redness, heat, pain and swelling of the inflamed part, and these may be
detected externally when the inflammation is not situated too deeply in the
body.
The redness and swelling are due to the dilated condition of the blood
vessels, and to the increased outflow of plasma and white blood cells from
the capillaries into the tissue. The degree of swelling in an inflammation
varies directly with the density and the vascularity (number of blood vessels)
of the tissue ; for instance, in loose vascular connective tissue, such as the
subconjunctiva, the swelling may be so great as to partially hide and cover
the cornea, whilst in denser vascular connective tissue, like the cornea, the
swelling is so slight as to cause merely a minute bulging over the inflamed
area.
PHYSIOLOGY AND PATHOLOGY. 21
The increased heat arises from the greater cellular activity, and the
pain from the increased pressure on the nerves by the over distended tissue.
In inflammation the first appreciable change is hyperseraia ^the blood
vessels dilating and containing an excessive amount of blood ; later the white
blood corpuscles occupy the peripheral, and the red cells the central portion
of the capillaries, and later still the white corpuscles and serum pass freely
out into the surrounding tissue, causing the latter to appear cloudy and
swollen. If the inflammation goes on still further, the red corpuscles also
gradually oo25e through the vessel wall, the circulation of the red corpuscles
in the centre of the vessel ceasing, and a complete stagnation of the blood
in the vessels follows, resulting in the formation of a blood clot, and later
in death of that part.
A more common termination is recovery from inflammation, the blood
vessels gradually becoming less dilated and parsing into their normal condi-
tion, the exuded colourless corpuscles either passing back again into the
capillaries or breaking up into a granular material, and, together with the
increased serum, passing out through the lymphatics into the general
blood stream again. An inflammation is merely an exaggeration of the
normal nutritive exchanges between the blood capillaries and the affected
tissue, and all degrees of severity and extent are encountered, being localised
merely to a small area, or involving one or many organs. If the irritant
be only mild, recovery without any permanent tissue changes results, but
if severe, recovery only takes place at the expense of destruction of tissue,
the latter being transformed into pus (matter).
Though any foreign body introduced into the tissues acts as an irritant,
and causes some inflammatory reaction, yet, if that body contain no
microbes, its presence is tolerated by the tissues, the latter enclosing it in
a capsule. This foreign body, if small, may become gradually absorbed, or,
if of dense structure, may remain encapsuled in the tissues. If very large it
may be slowly extruded from the body by the tissues. The innocu-
ousness or otherwise of a foreign body in the system does not then depend
so much upon its size or density as upon the presence of microbes.
Microbes. These are very minute living vegetable organisms, consisting of
Fig. 14.
Pneumococci. Mag^niiied i.ooo diameters.
2 2 PHYSIOLOGY AND PATHOLOGY.
a mass of protoplasm enclosed in an envelope, and are classified, according
to their shapes and their reactions to various staining reagents, into
numerous divisions, but such classification is necessarily rather crude. They
are very small, varying from one micro-millimetre (1/ 1000th part of a
millimetre) in length to a few micro-millimetres.
When circular in shape they are called cocci, and when rod shaped,
hacilli, whilst others are more filamentous and are called spirillce.
These divisions are very broad, and include hundretls of different kinds
of organisms in each division.
The commonest forms of cocci are perhaps the staphylococci, which
arrange themselves in bunches like grapes ; the streptococci, which arrange
themselves in lines ; and the gonococci and pneumococci, which arrange
themselves in pairs. A picture of the latter is shown, the microbes being
taken from the conjunctival sac of a patient suffering from corneal ulcer.
Diplobacilli. Magnified 1,000 diameters.
Bacilli consist of many different varieties, a common one being the
tubercle bacillus. This rarely attacks the eye, which is more often attacked
by a Kock Weeks bacillus, causing the pink eye so commonly seen in children.
The diplohacilli, so called because of being arranged in pairs, placed end
to end, cause angular conjunctivitis (Chapter III.).
These living organisms play a great part in the work of nature, as they
break up into more simple combinations the complex molecules of the
organic substances which form the bodies of plants and animals, or which
are excreted by them. In a few cases we know some of the stages of disinte-
gration, but mostly we are only familiar with general principles and results.
Thus the souring of milk and the ripening of cream and cheese are all due
to bacteria. Bacteria are also capable of giving rise to poisonous substances
(toxins) within the animal body, and also in artificial media. These are
of a very complex character, very little of their actual nature being
known, but each kind of organism produces a specific toxin. It is the
PHYSIOLOGY AND PATHOLOGY. 23
latter which is so inimical to the tissues of the body, and the rate of pro-
duction depends upon whether the conditions are favourable or otherwise to
the growth of the organism. The toxins also exercise a prejudicial influence
on the organism itself, the latter being frequently killed by the toxin.
Bacteria are human-like in their sensitiveness to outside influences,
their vitality being increased or decreased by unsuitable temperature and
food. Some prefer warmth, others cold ; some thrive on air, others without
it, and some grow better on such food as potatoes, others on jellies, etc.,
and this artificial food we term a culture medium. Excessive heat and cold
kill them, as do various chemical agents called antiseptics. Antiseptics are
not able to destroy microbes present in the body, as the vitality of the
organism is generally greater than that of the cell, and the antiseptic
would kill the cell whilst only weakening the organism. The latter
rapidly becomes revitalised, the dead cell being an excellent food tonic for
the microbe. Antiseptics have, therefore, for this purpose, fallen into
desuetude.
An aseptic body is one which contains no organisms^ and in surgical
operations everything is made aseptic. Though bacteria are necessary to
animal life, some of them, as above stated, are prejudicial, waging war upon
mankind, and it is with these latter organisms that we are mostly concerned.
Many forms of microbes are present in the air, and are carried by it into all
the cavities of the body communicating with the external air, as the nose
(and its accessory cavities), the bronchi and lungs. The food we partake
of carries organisms into the stomach and intestines, many of them being of
great assistance in digestion. These mostly only live on dead matter, such
as the food, breaking it up into simpler bodies. They are then called
saprophytes, but there are also present other bacteria which can attack
living animals or plants under certain conditions. These are called parasitic
bacteria, and they are commonly found on the surface of the skin and the
mucous membrane lining the cavities of the lungs, intestines, etc., but they
are not present in the tissues, the epithelial cells being the first of nature's
bulwarks protecting the body against the attack of these organisms. If
the organism be very virulent, or the epithelial cell be debilitated or injured,
the microbe may gain an entrance into the tissue. We will now consider
the results ot such an invasion.
The blood vessels of the affected part become dilated, and more lymph
and leucocytes pass into that area, the i^henomena of inflammation, as pre-
viously described, beginning. The leucocytes attack the invading agencies,
and, if victorious, the latter are eaten up, and the tissues return to the
normal again, but when defeated the tissue cells and leucocytes are killed,
lorraing, together with the toxines and the disabled microbes, a whitish fluid
called pus or matter. Nature brings up more leucocytes to resist the further
encroachment of the victorious microbes into the tissues, and she generally
succeeds in forming barricades, consisting of young white blood corpuscles,
which surround and cut off the infected area from the general system. This
limitation of the affected area leads to the formation of a localised collec-
tion of pus called an abscess, which gradually burrows to the surface and
bursts, so discharging its contents, and preventing the further absorption
24 PHYSIOLOGY AND PATHOLOGY.
into the system of the toxins which are produced in the abscess cavity. Jt
is advisable for the surgeon to expedite the liberation of the pus by incising
the abscf-ss, thus preventing the absorption by the body of the toxins.
When the organism overcomes these barriers erected by nature death of the
individual takes place. The ultimate result of the contest between the
contending forces of the body and of the microbes depends largely upon the
degree of virulence of the latter, and the degree of activity of the white cells
of the patient, which, in turn, is largely dependent upon the presence
or absence in the blood serum of certain bodies called opsonins, etc.,
that stimulate and increase the combative power of the white cells.
These bodies are distinct and specific for each kind of microbe, and it is the
toxins of the latter which incite nature to produce them.
When an abscess or severe inflammation occurs in a special tissue,
as muscle, the retina, etc., the affected area is not replaced by that, but by
ordinary fibrous tissue, and so the function of that area is lost, hence the
importance of cutting short an inflammatory attack in a specialised tissue.
Catarrhal inflammation is a term applied to mucous membranes such as
the conjunctiva, etc., where the inflammatory affection consists only in a
more congested (reddened) condition of the part, together with the pro-
duction of an increased quantity of mucus by the mucous glands, the latter
being present in great numbers on mucous surfaces.
The toxins produced by the bacteria at the inflamed area pass into
the general blood stream, and may cause an inflammation of another part
of the system. For instance, the ciliary body is frequently inflamed
(cyclitis) by the toxins generated by the organisms which frequently lodge
between the gums and the teeth, and the treatment of that cyclitis consists
in the extraction of those teeth.
Tubercle or consumption is due to a special bacillus, which, though
commonly found in the lung, may attack any portion of the body, although
it rarely invades the eye. The resulting pus is frequently caseous (like
cheese) in appearance. Syphilis is an infectious disease caused by an
organism which belongs to a higher species of microbe called the spirochita
pallida. It may be acquired by direct communication with an infected
person, or it may be inherited from infected parents. Many eye lesions are
due to this disease, the inherited variety causing a deep inflammation of the
cornea (so called interstitial keratitis) and also affections of the fundus.
The acquired variety frequently affects the iris, causing iritis ; retinitis and
choroiditis are also common consequences of this affection.
Ulceration. This is essentially of the same nature as the process of
suppuration, only that the purulent discharge, instead of collecting in a
closed cavity and forming an abscess, at once escapes upon the surface.
There is thus a loss of surface epithelium at the part, which appears as an
open wound or sore. In the eye a small ulcer on the cornea is not infre-
quent, and may be caused by a foreign body carried in by the air, or it
may be due to the attack of microbes.
PHYSIOLOGY AND PATHOLOGY. 25
Degenbbation. When a tissue is insufficiently nourished it degenerates,
losing firstly its highest function. This process is commonly observed in the
cornea of old people, appearing as an opaque whitish area (arcus senilis)
concentric with the corneal margin. The transparent corneal tissue becomes
changed into an opaque tissue, owing to interference with nutrition.
Degeneration may affect any tissue in the body, but the higher developed the
tissue the greater the tendency to degeneration.
Tumor. This is a localised swelling, composed of newly-formed tissue,
which fulfils no physiological function. Tumors tend to grow continuously,
quite independently of the growth of the body, and there is no natural
termination to this.
For clinical purposes tumors are arbitrarily divided into two great
classes ^the innocent and the malignant.
The innocent tumor may consist of any of the normal tissues of the
body, as bone, muscle, fibrous tissue, etc. They grow slowly, and are
generally surrounded by a fibrous capsule.
They differ from malignant tumors by the fact that they do not invade
or spread to a different portion of the body, but they may grow to quite a
large size, pushing aside and compressing adjacent parts. Malignant
tumors, on the other hand, show a marked departure from the normal
structure and arrangement of the tissues of the body. They tend to invade
the surrounding tissue by sending out prolongations or offshoots into it, and
they frequently spread to other parts, being carried either by the blood
stream or the lymphatics, and eventually destroying life.
Early operation offers the only chance of a complete cure, but the results
of such depend largely upon the degree or otherwise of the malignancy of
the growth and also upon its situation.
26
EXAMINATION OF THE EYE,
Chapter II.
The affections of the eye are of such a nature that their salient features
are verj' liable to be overlooked, unless great care is exercised, and too much
significance cannot be attached to the importance of habitually examining
the eye in a methodical manner.
Normal visual acuity cannot be accepted as any guarantee against the
presence of disease in the eye, and any improvement in vision obtained by
use of the pinhole disc is evidence only of some refractive error, but does not
exclude the possibility of disease in an ametropic eye a not unusual
occurrence. These cases shoAv the importance of not accepting a subjective
standard, and additional emphasis is given to this from the fact that the
subjective symptoms in ametropia and in pathological conditions are
commonly alike. The method to be pursued in an examination of the eye is
one which Avill enable us to correct the refractive error, and to exclude any
possible pathological change in as expeditious a mariner as is consistent with
thorough examination. The following method, almost universally practised,
is that which is most advisable for optical students to adopt :
1. The presence and appearance of any gross pathological condition
should be noted Avhilst the patient is stating his symptoms.
2. Visual acuity to be taken.
3. The transparency of the media, the healthiness of the fundus, and
the refractive error have to be determined, and for these purposes
the patient is noAV taken into the dark room, and the eyes examined :
(a) By focal illumination, especially Avith the view of detecting
slight opacities in the cornea and lens. The pattern of the
iris must be noted, and the pupillary actions tested.
(&) By transmitted light, using preferably a plane mirror and a
low illumination ; the transparency, or otherwise, of the lens
and vitreous being further determined.
(c) By retinoscopy.
(d) By the indirect ophthalmoscopic method, or this may be
omitted, and only the direct method used.
4. The objective results are now confirmed by subjective testing ; or the
keratometer may be used prior to such testing.
5. The muscular sense, the field of vision, and the light sense may be
examined when these are expected to throw any light on the cause
of the patient's symptoms, but investigation of the muscular balance
is advisable in everv case.
EXAMINATION OF THE EVE. 27
The examination of the various parts of the eye is given helo.v in more
detail, but it is only necessary to irivestigate them with such minuteness
when the patient's symptoms point to a possible lesion. For instance, with
muscae volitantes the vitreous must be carefully searched, in order to
exclude pathological opacities, or, if lachrymation be complained of, diseased
conditions of the lachrymal apparatus would be excluded as explained in
Chapter IV.
Whilst listening to the statement of the patient's symptoms, the observer
must make a rapid survey of the patient's face, brow and orbits, noting
especially the pasition, direction and size of the globes. If there be a
suspicion of a deviation of one eye, it should be roughly confirmed by
directing the patient to look steadily at the observer's finger, held in the
middle line, about an arm's length from him. The observer's other hand is
now placed in front of one eye, say the left, of the patient, and if the
latter's right eye has been fixing the observer's finger, nc movement of it will
be detected ; but if the eye had been deviated inwards a little, an outward
movement would be made in order to fix the finger, or if the eye were
deviated outwards an inward movement would be detected.
Also, on the observer withdrawing his hand from the patient's left eye,
no movement will be discernible in that eye, if the patient has normal
muscular equilibrium (orthophoria), but if esophoria be present, the eye
will be seea to move quickly out in order to fix the observer's finger, or an
inward movement will be detected if exophoria be present. Testing each
eye separately, the elimination of the grosser muscular anomalies can be
accomplished in a few moments by this procedure.
The position and margins of the lids should be noted, and also the
region of the tear sac, when lachrymation is complained of, and if simple
inspection discloses no alteration, pressure with the finger over the sac will
cause its contents to exude through the puncta.
Examination hy Focal Illumination. The lamp is placed at some
distance in front and slightly to the side of the patient, and the light is
condensed by means of a large lens (about -(- 10 to -}- 20 D), and brought
to a focus on the parts to be examined. Fine details may be looked for by
means of a corneal magnifier. The eye, as far back as the anterior surface
of the lens, can be examined by focal illuminatioir, and opacities in the
cornea or in the anterior part of the lens appear white. By focal illumina-
tion opacities in the cornea can be recognise<l which are perceptible in no
other way.
The anterior chamber should be observed with regard to its depth ; in
elderly people with glauoomatous tendencies it is often abnormally shallow,
whilst in myopic individuals the chamber is deeper than in the normal eye.
Irregularity in depth is one of the signs of a dislocated lens.
The iris should be examined for distinctiveness or otherwise of its
markings, and any evidence of old or present iritis noted.
28 EXAMINATION OK THE EYE.
The pupillary reaction to light (see (hap. VII.) should be tested, by first
concentrating the illumination upon it, and then withdrawing it ; also tin
other pupil should react consensually. The pupillary reaction to eonvergenc<
and accommodation may be tested, as contraction occurs Avith convergence.
The shape, colour and position of the pupil should also be noted.
Fig. i6.
Focal examination.
The anLeri(;r surface of the lens (an be examined by tiual illumination,
when opacities will appear Avhite.
The above examination only takes a few seconds, but the points must
be observed in a methodical niannev.
The transparencj' of the refracting media is now further tested by
projecting Hght into the eye from a distance of about one metre, using
preferably the plane mirror of the ophthalmoscope, with a low illumination,
which should come from behind the patient, being either above or to one
side of him.
The pupillary area appears red by transmitted light, and this is known
as the fundus reflex. Any opacity in the media appears as a black body
upon the red background, and its position can be determined by its apparent
displacement upon movement of the eyeball. The fundus reflex appears to
be situated in the pupillary area, and opacities in front of this plane appear
to move with the eye by transmitted light, and the further forward they
are situated the quicker the movement, so that an opacity stationed in the
upper portion of the cornea appears, when the eye looks down, to be on the
lower part. Opacities behind the plane of the pupil appear to move in the
opposite direction to the eye, so that a posterior lenticular opacity appear.-
to move upward as the eye looks down.
EXAMINATION OF THE EYE. 29
An opacity in the plane of the pupil, as one upon the anterior surface
of the lens, does not apparently change its relative position. On movement
of the eyeball, if stationed on the centre of the pupil, when the patient
looks straight ahead, it still appears to be in the centre when the patient
looks up, down, in or out.
Opacities in the solid media, cornea and lens move only with the eyeball,
but when stationed in the vitreous they move independently of the eyeball,
as will be seen by directing the patient to quickly look up and down, and
then straight ahead, when the opacities will be descried gradually .sinking
down.
Where further details of an opacity or of the media are desired, they
can be obtained by substituting high convex lenses beliind the small ophthal-
moscopic mirror, and approaching as near to the eye as possible, as if for
the direct ophthalmoscopic examination. The cornea may be seen with
a -f 20 to 4- 30 D, the iris and anterior capsule of lens with a -f-15 to -1- 20 D,
the posterior surface of lens with a -|- 10 D^ and the anterior portion of the
vitreous with a -|- 8 D ; the deeper the opacity be situated in the vitreous,
the Iftvss the strength of the lens which will focus it.
The retinoscopic examination should now be conducted, but as this book
is chiefly intended to treat of diseased conditions, information upon the use
of the instrument must be sought elsewhere.
Ophthalmoscopic Examination. Helmholtz introduced the first ophthal-
moscope, and prior to that it was thought that the blackness of the pupil
lay in the absorption of light rays by the choroid. Helmholtz, however,
demonstrated that the rays of light entering the pupil are not all absorbed,
but that the greater number are reflected back again through the pupillary
aperture. The-e cannot ordinarily be perceived, as the observer, in
attempting to intercept them, shuts out the source of light by the inter-
position of his face. Helmholtz overcame this difficulty by reflecting the
light, placed to the side of the patient, into the eye by a mirror in which a
central aperture was placed, and to which the observing eye is applied. No
details of the fundus could be thus obtained, but only a red reflex, and this
difficulty was overcome by the interposition of a strong convex lens (about
-I-12D) between the mirror and the observed eye, by means of which all the
rays reflected from the retina could be gathered into a single focus, and
thence diverging, could easily be brought to a second focus in the observer's
eye, the latter thus perceiving not a direct image of the fundus, but an
inverted aerial one formed by the convex lens, somewhere between it and
the observer's eye.
Later, anothei- method of solving the difficulty was discovered -by
approximating the mirror to the patient's eye, and placing before the sight
hole a lens of sufficient curvature to neutralise the patient's refraction, and,
if ametropic, that of the surgeon as well. By this means all the emerging
rays would naturally come to a focus upon the surgeon's retina. This was
effected by the invention of a magazine of lenses of varying strength,
which could be rotate<l in sequence before the sight hole until the suitable
lens was obtaned. By tilting the mirror, and providing an arrangement
by which it cnuld be rotated at will, the nocessarv amount of illumination
30
EXAMINATION OF THE EYE.
was obtained. This method is called the direct method of examination, and
an erect image of the fundus is obtained ; whilst the other is called the
indirect method, the image being an inverted one, the upper corresponding
to the true lower, and the right to the true left side.
The image obtained by the ophthalmoscope is considerably magnified,
but much more so with the direct (about 15 diameters) than with the
indirect (about 5 diameters). In both, however, the magnification is
influenced to some extent by the refraction of the eye, being greatest in
indirect examination of high hypermetropia, and least in high myopia,
whJst it is the reverse with the direct method, the largest image being
obtained in myopia, and the smallest in hypermetropia.
Each of these two methods has its advantages. Bj' direct examination
there is a large magnification, the estimation or confirmation of the refrac-
tion being possible at the same time as the fundus is examined. Elevations
and depressions can not only be appreciated (as also in the indirect method),
but can be directly measured, and any opacities in the different refractive
media can be located and examined.
The advantages of the indirect method are that it gives a more general
view of the fundus, and when the media are hazy it is possible to get a view
when one cannot do so by direct examination. In very high myopia the
direct examination is rather difficult, whilst it is quite easy by the indirect.
Ftg. ij.
Direct ophthalmoscopic examination.
Note observer is standing to the side of patient, and that the latter's face is
not obscured by that of the observer.
The lamp is behind the observer.
Both methods should be learned, but the direct method will prove by far
the most useful in practice. It is advantageous for beginners to practise
on a dilated pupil, but when once thoroughlj^ conversant with the instru-
ment a mydriatic is very rarely necessary. Good illumination is essential,
and preferably the room should be darkened. The light is generally fitted
on a mo\ able arm, and placed to one side of, and slightly behind, the patient,
about the level of his ear, whilst the patient is sitting down. It is more
convenient to examine young children standing.
EXAMINATION OF THE EYE. 31
In emmetropia the rays emerge from the patient's eye in a parallel
beam, and so are focussed upon the observer's retina (provided he is
emmetropic or is wearing his full correction) without any accommodative
eflFort, but if accommodation bo used, the rays will be brought to a focus
anteriorly to the observ^er's retina, and only a blurred image of the fundus
will be seen.
In hyperopia the rq,ys emerge divergent, and the observer has either to
accommodate in order to see the fundus distinctly, or else to substitute
behind the sight hole a convex lens equivalent in strength to the patient's
refractive error.
In myopia the rays emerge convergent, and it is necessary for the
observer to place a concave lens, corresponding to the refractive error, before
the sight hole, in order to see the fundus clearly.
Fig. iS.
Indirect ophthalmoscopic examination.
In the indirect method the patient's right eye should be examined by
the observer's right eye, and his left by the left eye, or the observer may
use the same eye for both. Seated in front of the patient, at a distance
rather less than an arm's length, the observer, holding the mirror close to
his eyes, reflects the rays from the lamp into the patient's pupil, illuminating
it by the red glare, known as the " fundus reflex." Either a plane or a
slightly concave mirror may be used, and it is preferable to put up a + 3D
behind the sight hole. The next step is to locate the disc, which, owing to
its colour, is the most conspicuous object, and to see this the patient must
be directed to look a little inwards, towards the observer's opposite ear :
that is, the observer's right ear in examination of the right eye, and vice
versa. A slightly whitish reflex is generally seen, and then the object lens
(about 4- 12 D), held between the forefinger and thumb of the other hand, is
placed in front of the patient's eye, about two inches from it, and steadied by
resting the tips of one or two disengaged fingers against the patient's brow.
32 EXAMINATION OF THE EYE.
The convex lens is now removed just far enough from the patient's eye to
cause the margin of the pupil to disappear out of the observer's field of
vision, and the latter then ceases to look into the eye, but fixes his gaze
upon the convex glass, when the inverted image of the fundus should at
once become visible, appearing to be situated in the convex lens, though it
really is in the air somewhat on this side of the lens. By moving his
own head a little backAvards and forwards, or by slightly altering the posi-
tion of the lens, approximating, withdrawing, or slightly tilting it, the
observer will soon succeed in seeing an image of the optic disc and retina.
This slight shifting of the head and lens can only be learned by practice,
and the beginner, at first, will be much troubled by a reflection of the lamp
from the surface of the cornea, which he will soon learn to disregard. It is
preferable to use quite a large convex lens (2inch diameter), so obtaining a
larger field, and rendering the corneal reflex le-s troublesome. The observer,
if ametropic, should either wear his correction, or have it inserted behind
the mirror.
In the direct method the light is arranged at about the level of the
patient's ear, slightly to one side and behind it, and the observer sits or
stands at the side of the patient, iising the right eye for the patient's right,
and the left for the left. The small tilted mirror of the ophthalmoscope is
used, and is so arranged that the apex or non-tilted edge points towards
the observer's nose; an imaginary line running from the centre of the tilted
edge to the centre of the non-tilted edge (apex) should be in the horizontal
plane. The upper end of the ophthalmoscope rests just underneath the
observer's eyebrow, and the difficulty which beginners often experience in
well illuminating the pupil is most frequently due to an unconscious slight
tilting of the ophthalmoscope, and, as a result, they are looking obliqrely
through the sight hole, so cutting off much of the illumination.
In overcoming the difficulties of illumination, beginners Avill find it
most useful to practise throwing the light at will to any part, such as the
back of one's hand. Having obtained a good reflex, the observer must
approach as close to the patient as possible, especially with myopes. In
order to bring the disc into view, the patient is directed to look a little
inwards (about 15 degrees), and the observer, in order to relax his accommo-
dation, should always imagine that he is looking through the patient's head
into infinity. If no details of the fundus can be detected, even though the
red glare is distinct, higher concave lenses are put up until the fundus is
clearly seen. At first the observer, always unconsciously, 'exercises his
accommodation a fault which time and practice rectify. After the disc
and vessels have been observed, the macula is examined by asking the
patient, making a movement of the eye only, to look directly into the
observer's mirror. This area is the most difficult part of the fundus to see,
owing to the greater contraction of the pupil which takes place when light
is concentrated on it, and also to the absence of any distinctive markings
in this region. Confusion is caused also by the troublesome corneal
reflex being more noticeable. The latter difficulty can be partly obviated
by looking through, not the centre, but either the inner or outer side of
the cornea.
EXAMINATION OF THE EYE. 33
The other parts of the fundus are afterwards examined.
The diflficulties with direct examination are chiefly caused by : -
(1) Jllumination, owing to the tendency to look obliquely through the
sight hole.
(2) Accommodation. The observer must relax his accommodation m
habit acquired by practice only. It is advisable always to assiduously us*^
convex lenses of increaping strength, or concave lenses of diminishing
strength, behind the mirror, endeavouring with each increase or decrease-
to see clearly the details of the fundus. Though the beginner will find it
difficult at first to keep both eyes open during the examination, yet he must
always strive to do so, this being inost helpful in preventing accommodative
effort.
(3) The reflection of the lamp from the surface of the cornea. This is
most annoying at first, but practice, and looking through the cornea a little
to one or other side of its centre, quickly overcome this difficulty.
(4) Very dark fundi and high myopes. These prej-ent greater difficulties
than usual, and in the latter cases it is essential for the observer lo approach
as closely as possible to the patient's eye, practically touching the lashes.
The attainment of proficiency in the direct method of examination
should be early acquired, as it will prove of much more practical value than
the indirect, owing to the larger magnification obtained and to the con-
firmation of the retinoscopic examination it affords.
In estimating the refractive error of the patient it is necessary for the
observer to relax his accommodation, and, if ametropic, either to wear his
correction or to subtract the amount of his ametropia from the total result
obtained. In the direct examination patients more completely relax their
accommodation than in any other objective examination, and so it afFonls
a most valuable guide in suspected cases of ciliary spasm.
Although, theoretically, the macula should be taken in estimating the
refractive error, yet the absence of any distinctive vessels in that region
makes it preferable to fix the smaller ones leaving the disc. The observer
fixes one of the vessels, and, while doing so, rotates convex or concave
lenses, as the case may be, before the sight hole of the mirror, until he has
found the highest convex or lowest concave lens with which the disc and its
vessels are plainly seen. This lens, after the subtraction of his own refrac-
tive error, will represent the <legree of H or M respectively.
It is not a <lifficult matter to estimate the ditferonce of refraction in tiie
vertical and horizontal meridians, as a vessel running vertically gives its
the refraction in the horizontal meridian and vice versa, and the differencf*
between the two represents the astigmatic error. Oblique astigmatism
presents greater difficulties, owing frequently to the absence of vessels in
the plane corresponding to the astigmatism.
34
EXAMINATION OF THE EYE.
In determining the refractive error^ the observer's mirror must be
a plane one, and he should approach closely to the lashes of the patient. It
is more convenient to have both a plane and a slightly concave mirror fitted
for direct ophthalmoscopy, as the latter brings out the macula more dis-
tinctly ; but the disadvantage of using both types of mirror lies in the slight
difference of colour noted in the fundus, the concave causing it to appear a
little lighter.
Differences in level can be detected and calculated, a depression
(cupping) requiring a lens of less power, and an elevation one of greater
power, than that needed for the surrounding fundus, but this is not so
sensitive a test as that of parallactic displacement. A difference of 3 D is
equivalent to an alteration in level of 1 ram .
35
THE EYELIDS AND CONJUNCTIVA.
Chapter III.
ANATOMY OF THE LIDS.
The lids are. in origin, folds of the external skin, which push their way
over the eyeball to cover and protect it. The boundaries of the upper lid
are formed by the eyebrow, but the lower lid passes, without any sharp line
of demarcation, into the cheek.
Of the two eyelids, the upper is the larger, the deeper and the more
movable. The skin covering the lids is very thin, and is only loosely
attached to the tarsus underneath, so that it can be moved independently,
thus wrinkling readily when the eyes are opened, and becoming stretched
when they are closed. Because of the ease with which the skin can be
displaced, cicatrices, either in the lids or in their vicinity, readily distort
them, so producing ectropion, or entropion. There is no fat in the tissue
beneath the skin, and this laxity of the subcutaneous tissue is favourable to
the accumulation either of blood ecchymosis, noticeable in a contused eye
or of fluid seen in kidney disease. In the neighbourhood of the free
border of the lid, the skin is firmly united to the tarsus.
Fig, ig.
Perpendicular section through the upper lid.
CCC EyeUshes. Z Sebaceous glands opening into the fvWlicle of the cilia. EE Fine
hairs on kin surface of lid. T Tarsal cartilage. M Opening of Metbomi.4n glands (GO.
L Levator palpebral superioris and F Portion of the latter going forwards to be inserted
into the skin. P Muller's muscle. O Orbicularis muscle. B it H Conjunctiva. 5' Skin.
36 THE EYELIDS AND CONJUNCTIVA.
The aperture between the lids is called the interpalpebral aperture or
fissure, and the mean width of it varies with the individual. The shape
and width of this aperture has the greatest influence upon the expression
of an eye : An eye popularly called small bears no reference to the size of
the eyeball, but only to the width of the palpebral aperture. Eyes which
are reputed to be large and beautiful are really only those with a wide
palpebral fissure.
In all cases a small arc of the cornea is covered by the upper lid, but
the upper level of the lower lid varies a great deal, perhaps not quite or
only just reaching the corneal limbus, or even extending on to a portion of
the cornea.
Each eyelid consists of the following structures from before backwards :
(1) Skin. This is thin and delicate, devoid of subcutaneous fat, and
connected with subjacent structures by loose tissue.
(2) Palpebral Portion of the Orbicularis Muscle. A fine layer of
arching fibres, which are inserted into the internal and external tarsal liga-
ments. Its function is to firmly close the lid. In the upper lid is also
found the levator palpebrpo superioris, which raises the lid.
(3) Tarsus. This consists of fibre cartilage^ and forms the chief frame-
work of the lids. The upper is the larger of the two, and inserted into its
upper margin is the levator palpebrse superioris, which is also continued
over the surface of the tarsus. Associated with tins muscle is a small layer
<jf unstriped muscle, called Muller's muscle, which assists the levator in the
elevation of the lid. Each tarsus is connected to the orbital arch by a
strong band of tissue named the septum orbitale, the upper one being much
stronger than the lower. Both externally and internally the tarsi are
attached to the adjacent bone by fibres called the external and internal
tarsal ligaments. The internal tarsal ligament, or tendo oculi, as it is
often called, is much the stronger and more defined of the two, and it can
be distinctly felt when the eye is turned strongly outwards. It is an
important guide, for beneath it lies the lachrymal sac.
(4) Meibomian Glands. These are modified sebaceous glands, and are
placed at right angles to the free margins of the lid, on the posterior
border of which they open. They lie imbe<lded in the posterior or conjunc-
tival surface of the lid, and can sometimes be seen, on everting the upper
lid, as fine yellow lines arranged in a radiating manner. These glands
sometimes become blocked, forming meibomian cysts.
(5) Palpebral Conjunctiva. ^This is closely adherent to the tarsus.
The free margin of a lid is flattened, and along its anterior border are
placed the cilia or eyelashes, which are grouped in two or three rows. The
upper ones are thicker, larger and more curved than the lower. Around
the insertion of the cilia into the skin are placed small sebaceous glands,
which secrete an oily material for lubricating purposes. When these little
inlands become inflamed, the condition is popularly called a stye.
On the posterior border of the free margin of the lid, the orifices of the
meibomian glands are situated.
THE EYELIDS AND CONJUNCXn A.
The points of meeting of the two lids are called the commissures or
canthi. Tho external is well defined and angular, but the internal is
rounded and elongated.
On either lid, near the inner canthus, and situated on a papilla, is
placed a minute opening. This is called the punctum lachrymale, and it
allows the tears to escape into the tear duct-
Fi^. 20.
'I'he skin and muscular fibres of the orbicularis have been removed from the lids and the
parts surroundin: them, thus exposinjf the tarsal cartilage and ihe septum orbitale, which
connects the cartilage both above and below with the n.iyhbouring bone.
Z" Tarsal cartilage, i? Septum orbitale. F Lachrymal gland. 5' Internal tai sal ligament
which lies just in front of (A) Lachrymal sac. F Represents the surrounding bone.
Movements of the Lids. In opening the eye^ the upper lid is raised by
the levator palpebrse si^perioris, whilst the lower sinks a little by its own
weight. Muller's muscle also assists the levator in raising the lid, and this
muscle, being supplied by the sympathetic nerves, is occasionally paralysed,
whilst the levator is unaffected, and then we note a slight drooping of the
upper lid, together with a slight dilatation of the pupil (the dilator pupillte
being also supplied by the sympathetic).
In moderate closure of the eyes the upper lid sinks by its own weight
and the lower lid is slightly raised by the orbicularis muscle. The fre
borders of the lid do not come in contact throughout their whole extent at
once, but the closure commences at the external canthus, and runs succes-
sively to the inner canthus. This action propels the tears from the
outer canthus inwards towards the puncta, from whence they escape into
the nose. In sleep the lids are closed, and the eyeball rolls upwards.
Tight closure of the lid is effectetl by strong contraction of the
orbicularis muscle. Winking, though it may be voluntary, yet generally
results through reflex action, as when there is a foreign body or a sense of
dryness in the eye. Winking covers the surface of the ejeball with a thin
layer of tears, which remove dust from the eye and prevent dryness. It
also drives the lachrymal fluid into the puncta. Interference with winking
will cause epiphora (flowing of tears over the border of the lid on to the
cheek), and the cornea would tend to become inflamed, owing to the colle<-
tion of dust upon it. The levator palpebrse superioris, which raises the
upper lid, is supplied by the facial or seventh nerve, and the orbicularis,
which closes the eye, is supplied by the third nerve.
38
THE EYELIDS AND CONJUNCTIVA.
DISEASES OF THE LIDS.
HyrER^MiA, or increased redness of the margins of the lids, is a
frequent concomitant of refractive errors, of an irregular mode of life, etc.
Persons of light complexion and blonde or reddish hair are particularly
susceptible, and in such individuals the condition may last more or less all
their life, in spite of both general and local treatment. Treatment consists
in the correction of the refractive error and the enforcement of a regular
mode of life. The eschewment of stimulating foods, as tea, coffee, stimu-
lants, tobacco and red meat, is also advisable. Local treatment is as in
blepharitis.
Blepharitis. Inflammation of the border of the lids so-called
blepharitis appears under two forms : blepharitis squamosa, and blepharitis
ulcerosa.
Blepharitis squamosa. In this condition the skin between and around
the lashes is covered with small white or gray scales, appearing as if bran
had been scattered over it. The scales are easily removed by simple
washing, and teneath them the skin is found to be red, but not ulcerated.
Frequently the cilia or lashes fall out, but, as the hair follicles are not
destroyed, they afterwards grow again.
<^-^:
Fig-. 21.
Vertical section oF skin, showing root of hair and follicle.
5" Stem of hair. L Skin level. R Root of hair. ^ Apex of root. F Hair follicle.
G Sehaceus glands, which secrete oil for the hair.
Blepharitis ulcerosa. -In this form the border of the lids is covered with
yellowish crusts, on removal of which the skin appears red, and around the
hair follicle that is, where the cilium is inserted into the skin a little pus
is seen, or a slight yellowish elevation, or the latter may have ruptured
and the pus escaped, when a slight ulcer is revealed.
THE EYELIDS AND CONJUNCTIVA. 39
This condition is due to a microbe attacking the hair follicle, producing
inflammation, followed by the formation of a little pus, and later by destruc-
tion of the follicle. The cilium, as in squamosa, falls out, but it does not
grow again, the root of the hair (the follicle) having been destroyed. One
follicle after another is attacked, until perhaps the whole of the lashes are
destroyed.
Hairs upon any portion of the body consist of a root, the part imbedded
in the skin, and the stem, the projecting part. The term root is really a
misnomer, as it is not the part from which the hair grows. When we
epilate a hair, including the so-called root, another grows, the reason being
that the real root of a hair is the hair follicle. This consists of cells lining
the so-called root, and from these a hair grows. The follicle remains intact
when a hair is epilated. Destruction of a hair follicle not only results in the
falling out of that hair, but no further growth can take place.
In blepharitis ulcerosa the microbe infects the hair follicle, so destroying
and preventing the growth of a new lash, and this factor makes it a much
more serious disease than blepharitis squamosa, in which the follicle
remains intact.
When blepharitis has been present for some time, many of the following
permanent changes are produced in the conjunctiva and the lids
(a) Chronic conjunctival catarrh is constantly present.
(6) Increased thickness of the margins of the lids takes place and
causes drooping of the lid (tylosis).
(c) In blepharitis ulcerosa the whole of the lashes may be destroyed,
and there remains upon the border of the lid perhaps only a few
small downy hairs. This condition is called madarosis.
(d) Changes in the position of the lids may take place, either becoming
inverted (entropion) or everted (ectropion).
For treatment, attention to general health is indicated. Locally the
refractive error must be corrected, and in blepharitis squamosa soothing
mercurial ointments are applied at night, and alkaline lotions are used in
the morning to remove the scales.
In blepharitis ulcerosa the infected lashes must be epilated, and
vaccine treatment is of great service in the protracted cases. Both forms of
blepharitis strongly resist treatment, which must often be continued over a
period of years.
HouDEoLiJM (Stye). --This is an inflammation of the sebaceous (or oih
gland which opens into the hair follicle of the eyelash. It is intensely
painful, and it produces a localised redness and swelling at one part of the
lid margin. The skin over the swelling gets redder and redder, and the
swelling gradually increases. Later pus makes its appearance as a yellowish
spot in the red swelling, and it generally bursts through near the border of
the lids. After the escape of the pus the swelling and redness rapidly
abate. Patients often have repeated attacks, as, owing to their weakened
condition, thev are liable to reinfect themselves.
40
IHK EYELIDS AND CONJUNCTIVA.
In the acute stage the application of hot fomentations and the incising
of the swelling rapidly cut short the attack. To prevent recurrence, th'
refractive error must be corrected, and in the most obstinate cases tho
patient's resistive powers must be raised by vaccine treatment.
Vertic-il s:
H Hordeolum,
Chalazion or Meibomian Cyst
ion of lid, showiiijr the different sites occupied by
hordeolum and a niarg^inal chalazion.
L Eye lash. C Chalazion. M Meibomian gland.
This is a chronic affection of th.-^
Meibomian glands. It was formerly supposed to be due to an obstruction
in the duct preventing the outflow of the secretion (sebum), but more
probably it is an inflammatory condition caused by microbe-;. Tt appears as
L halazion on upper lid, the c\ ellds being: gently closed.
a small hard swelling, generally in the upper lid, which gradually becomes
larger and larger until it reaches the size of a pea or bean. The skin ovoi-
the swelling is movable, and can be displaced from side to side. Later the
chalazion undergoes degeneration, a viscid fluid forming in its centre,
thus producing a cyst. This fluid increases, and the cyst generally ruptures
on the conjunctival surface of the lid, or more rarely on the skin surface.
Occasionally the cyst becomes infected by microbes, and a small abscess
then results. Chalazia affects adults more than children, and are often
associated with refractive errors and conjunctival catairh.
Prevention consists in the prescription of correct glasses and the treat-
ment of any local catarrh. To remove the chalazion it is necessary to
incise it and curette its walls.
THE EYELIDS AND CONJUNCTIVA. 41
mREGULARITIES IN POSITION OF THE BORDERS OF THE LID.
Trichiasis. This consists in an irregular displacement ot the lashes,
which, instead ot looking forward, are directed moro or less backward,
coming in contact with the cornea. It may be partial, or may involve the
w hole of the cilia, but even when of slight degree the displaced lashes cause
Kreat irritation by brushing against the cornea, causing the latter to
l>ecome inflamed, and not infrequently ulcerated. A constant sense of a
foreign body in the eye, accompanit^l by photophobia and lachrymation, is
always present. liater, superficial opacities are prodiiccnl on the cornea,
chiefly on the lower section. Not infrequently persons are tormented by
recurring ulcers, until at length the physician discovers a minute
lash, incurved and touching the cornea, which has been the cause of all
the trouble.
For the natural growth of the lashes it is necessary that the follicles
sliall be healthy, and also placed in a proper position in the lid. Trachoma
displaces the follicles, and is the most frequent cause of trichiasis.
Distichiasis is ^i cwngenital condition in which there are two lows of
cilia, one looking forwards, and the other directed backwards.
Active treatment must be directed against any cause of the trichiasis
wliich may be present, as blepharitis ulcerosa and trachoma.
It is not only necessary to opilate the incurved lashes, but the follicles
must also be destroyed in order to prevent the lashes growing again. This
is generally accomplished by electrolysis. Where many lashes are affected,
epilation is not suitable, and the condition is rectified by an operation on
the lid.
Entropion. In this condition the margin of the lid is rolled inwards.
The distinction between entropin and trichiasis is only one of degree. In
the latter the border of the lid is properly situated, but the posterior
margin of the lid is rounded off^ and the cilia are turned backwai*ds. In
entropion the whole margin of the lid is turned in, and we can only see it by
<1 rawing it outwards. The evil results of entropion are the same as those of
trichiasis. Two varieties of entropion are distinguished according to the
causal lesion.
Entropion sint.fticuiii. ^fhe incurved margin is ca-.ised by a more or less
constant spasm of the orbicularis muscle which closes the eye, especially
when the skin of the lid is redundant and flabby. The spasm of the orbi-
culosis, so called blepharospasm, is sometimes met with in elderly people.
Cicatricial entropion. This is due to a conjunctival scar, resulting
perhaps from trachoma, or a burn, contracting and pulling the lid in.
Generally operative measures have to be resorte<l to as a remedy for
entropion.
42 THE EYELIDS AND CONJUNCTIVA.
Ectropion consists in an outward rolling of the lid, so that its con-
junctival surface looks forward, and is entirely the opposite of entropion
There are many degreevs, and the lowest is where the internal margin of the
lid stands off a little from the eyeball eversion of the border of the lid.
With the eversion of the lid the puncta are not in apposition with the
eyeball, and so the tears cannot escape into the tear duct, and thus overflow
on to the cheek (epiphora).
The epiphora tends to cause more eversion of the lid, owing to pro-
ducing increased redness and thickening of the conjunctiva, and so a
vicious circle is created, and natural return to the normal cannot take place.
The condition gradually increases until the larger part of the conjunctival
surface of the lid becomes exposed ; the exposed conjunctiva then hyper-
trophies, and occasionally looks like proud flesh. Ectropion is most common
in the lower lid, and is the result of blepharitis, trachoma, and other
chronic conjunctival troubles.
Operative treatment is generally indicated, and in the early stages
merely slitting up tlie canaliculus, in order to make an outlet for the tears,
often suffices. Local treatment must be directed against the cause of this
condition. The patient must be warned to wipe away his tears from below
upwards, and not, as is usually done, from above downwards, as the latter
procedure draAvs away the puncta further from the eyeball.
Lagophthalmus. This is an incomplete closure of the palpebral fissure
when the lids are closed. In the lesser degrees, squeezing the lids tightly
together will effect a closure, but in sleep when there is only a gentle
closure, and the eyeballs roll upwards the eyes will remain open, and the
lower part of the cornea is exposed to the air. As the result of this the
cornea becomes dry and inflamed in the exposed area, and later ulceration
will take place, unless the eye is kept closed by a pad and bandage applied
at night.
AFFECTIONS OF THE PALPEBRAL MUSCLES.
Spasm of the Orbicularis (Blepharospasm). The orbicularis muscle
is attached at the inner and outer canthi, and between them it spreads
completely over the lids. Its function is to close the eye, and it is supplied
by the facial or seventh nerve. In blepharospasm the lids are constantly
screwed together, and it is either an accompanying symptom of other eye
diseases, or it forms a disease by itself essential blepharospasm or
nictitation.
In the following diseases blepharospasm is a prominent symptom :
(1) In the lodgment of foreign bodies in the eye ;
(2) In corneal diseases, especially those accompanied by ulceration.
(3) In phlyctenular conjunctivitis.
(4) In increased sensitiveness of the retina, which is occasionally seen
in anaemia and debility.
THE EYELIDS AND CONJUNCTIVA. 43
Essential blepharospasm is distinguished by the fact that in it the eyes
themselves are found to be perfectly normal. It generally attacks young
persons and the female sex, and is extremely annoying to the patient, as
the constant spasm prevents them doing any continuous work.
All sources of irritation must be carefully searched for, and the refrac-
tive error corrected. In some cases relief is not obtained by Chese means,
and tinted glasses become necessary, but are only advisable after exhaustion
of all other remedial measures.
Paralysis of the Orbicularis. This condition is only found in con-
junction with paralysis of the other facial muscles. The patient cannot
close his eye tightly, and the lower lid falls away slightly from the eyeball,
causing eversion of the puncta and epiphora.
Ptosis (Drooping of the ITpper Lid). The upper lid is raised by the
levator palpebroe superioris muscle, which is supplied by the third nerve.
MuUer's muscle, a small layer of unstriped muscle fibres, supplied by the
sympathetic nerve, also slightly assists.
All degrees of ptosis exist, from a slightly noticeable drooping of the
upper lid, to a complete prolapse of it ; the lid, devoid of wrinkles, almost
completely covering the eyeball.
So long as the ptosis is not so marked as to cover the pupillary area,
no interference with vision results, and even where it does hang down
slightly in front of the pupil, the patient, by tilting his head backwards
and wrinkling his forehead, can to some extent overcome the difficulty.
Ptosis may be either acquired or congenital. The former is due to
paralysis of the third nerve, and other ocular muscles will be similarly
affected .
A slight drooping of the lid, together with a dilatation of the pupil, is
due to interference with the sympathetic nerve, and enlarged glands in the
neck are often the cause of such interference. Congenital ptosis, unlike
acquired, aflFects both eyes.
In congenital ptosis an operation is necessary, and in the acquired
form the nerve legion must be treated.
ANATOMY OF THE CONJUNCTIVA.
The conjunctiva is a delicate membrane lining the internal surface of
the lids (palpebral conjunctiva) and the anterior surface of the eyeball
(ocular or bulbar conjunctiva). The palpebral conjunctiva is firmly
adherent to the tarsus, and at the luitcnOr free margins of the lids it
44 THE EYELIDS AND CONJUNCTIVA.
becomes continuous with the skin, wliilst posteriorly it is reflected on to the
eyeball, the line of reflection being termed the fornix. To see the lower
fornix, the lower lid must be drawn down, whilst the patient looks upwards.
The upper fornix is difficult to see, unless we make a double
eversion of the lid. It is the loosest part of the conjunctiva, the latter
being so abundant as to lie in horizontal folds, and thereby free movement
of the eyeball, independently of the lid, is ensured.
The conjunctiva bulbi covers the anterior surface of the eyeball, and
has no aperture corresponding to the cornea, but continues, though only as
a few epithelial cells, over the latter. The bulbar conjunctiva is much
paler than the palpebral, and is loosely connected with the sclerotic by a
layer of areolar tissue the conjunctival or episcleral tissue but around
the corneal margin the conjunctiva is firmly adherent to the scler.i, and is
liere called the " limbus conjunctiA^se." At the inner side of the eye (inner
canthus) the reflection of the bulbar conjunctiva on to the upper and lower
jids forms a vertical fold known as the plica semilunaris, which is a
vestigial remnant of the third eyelids, seen in birds. This fold forms the
outer boundary of a small space called the lacus lachrymalis, in which is
situated a red fleshy elevation, the lachrymal caruncle, upon which a few
downy hairs are often found.
The conjunctiA'^a is not richly supplied by blood vessels, those present
being twigs from the terminal branches of the ophthalmic artery. Upon
the globe the vessels form a slender radiating network, gradually dimin-
ishing in size as they pass from the periphery to the cornea. This accounts
for the redness, in conjunctival inflammations, being more marked at the
periphery than around the cornea. The nerve-supply is from the oph-
thalmic division of the fifth nerve. Numerous glands, secreting mucus,
which acts as a lubricant, are found in the conjunctiva.
DISEASES OF THE CONJUNCTIVA.
Conjunctivitis. The slighter forms are called catarrhal conjunctivitis,
and the severer, purulent ophthalmia or acute blennorrhoea.
Catarrhal Conjunctivitis. The patient complains of slight itching and
burning in the eyes, often accompanied by the sensation of the presence of
a foreign body, due to flakes of tough mucus in the conjunctival sac. A
characteristic feature of catarrh is that the symptoms are least pronounced
in the morning, but gradually incease as the day passes on. The
inflammation causes increased secfetioUj which in the slight cases
is merely mucus, but in the sever types is of a purulent character
(matter). The secretion dries upon the edges of the lids during sleep, and.
on waking, the latter are gummed together. Photophobia (intolerance of
light) is not a prominent symptom. The cornea is clear, and the pupil
reacts to light.
THE EYELIDS AND CONJUNCTIVA.
45
Refractive and muscular errors are the commonest causes of those mil<i
cases, in which tiiere is only slight redness and secretion, but where the
injection is' greater, and the secretion more profuse, microbes are the
exciting cause. Certain microbes produce definite clinical types of con-
junctivitis.
Angular Conjunctivitis. This is a very common type, and the redness
is only, or specially, marked at the inner and outer side? of the eye. It is
due to a specific organism called "diplobacillus." The correction of the
refractive error never cures this condition, iiowever mild it appears.
r
Jink Eye. .Vnother common acute catarrhal condition, popularly
called " pink eye," or blight, owing to the uniform retldish appearance of
the white part of the eye, is caused by another specific organism. It is verj-
infectious, and chiefly affects children.
Conjunctivitis sometimes occurs after the action upon the eye of intense
light as that reflected ^rom snow, or direct from the electric arc.
There is intense conjunctival injection, pain, photophobia and lachrymn-
tion, also slight opacities and erosions of the cornea occasionally occur.
These symptoms are produced by the action of the ultra violet rays.
Diagnosis.- The gumming of the lids is the most important sign. By
focal illumination mucoid secretion is seen upon the conjunctiva, and often
on the edges of the lids. The redness of the eye, due to conjunctival vessels,
has to be distinguished from the injection due to dilatation of the ciliary
vessels caused by deeper inflammations of the eye, as in keratitis, iritis and
cyclitis. The following states the differences:
Conjunctivitis.
Gumming of lids.
Not much photophobia.
Very slight pain.
Redness of eye deepest .-it
peripherj', and scarlet in^
color.
Individual vessels plainly seen,
tortuous in shape, and
movewiihtheconjunctiva,
as can be shown by asking
patient to look up, and
then moving the lower lid
on the eyeball.
Cornea clear.
Pupil active.
Keratitis.
Not present.
Great photophobia.
Great pain.
Deepest around cornea, and
pale red in color.
Vessels not distinctly seen,
and do not move with
conjunctiva, as the>" arc
sitiiatttd beneath it.
Cornea ha/\ .
Pupil contracted, but dilates
regularly.
Iritis.
Not present.
Much photophobia.
Great pain.
Deepest around cornea,
pale red in color.
and
Vessels not distinctly seen,
and do not move with
conjunctiva, as they are
situated beneath it.
Generally clear.
Pupil contracted, and dilatt
irregularly.
.\cuit Blennorrhoea (or acute purulent conjunctivitis). This occurs niost
frequently in babies about a week old, and is generally due to the gonococcus
microbe. The lids and conjunctiva become very red and swollen, and pu.s
literally pours from between the lids in a severe case. Infection of tlie
cornea frequently takes place, resulting sometimes in its destruction. It
is one of the commonest causes of blindness.
46
THE EYELIDS AND CONJUNCTIVA.
Chronic Catarrhal Conjunctivitis is rarely the sequel oi an acute attack^
but generally occurs in patients who are below the usual standard of health,
and in those whose livelihood entails long-continued use of their eyes for
fine work, especially if any refractive or muscular error be present. The
eye is red and irritable, and often a sense of discomfort, and some watering
(lachrymation), on exposure to light are complained of. Reading tires the
eye, and causes it to become more reddened. In old people the frequent
dragging upon the lower lid in the act of wiping the eye, on account of the
slackness of the tissues, causes the punctum to be slightly drawn away from
the eyeball, and the tears overflow on to the cheeks. This excoriates the
lids and aggravates the symptoms, forming a vicious circle, and preventing
a natural cure from ever taking place.
Correction of refractive and muscular errors is most important. Local
applications, as boric acid, zinc sulphate, etc., hasten the patient's progress.
Where the punctum is everted, surgical measures are generally indicated,
such as slitting up the canaliculus.
Follicular Conjunctivitis is characterised by the presence of follicles,
situated chiefly in the lower fornix, which is seen on everting the lower lid.
They are small round granules, slightly smaller than the head of a pin, and
of a pale and translucent aspect, puffing up the conjunctiva in the form of
small eminences. A few or many may be present, and in the latter case
they are arranged in rows. The symptoms are those of conjunctival irrita-
tion. The follicles are met with in young boys, especially those with
refractive errors, and it is very important to distinguish this affection from
trachoma, which is an infectious and very serious disease, owing to the
tenacity with which it resists treatment. The differences are shown herewith
Follicular Conjunct tint is.
Slight redness and irritation of eyes.
Follicles gfenerally in lower fornix, but never
on palpebral conjnnctiva.
Arranged in rows.
Does not cause subsequent scarring of con-
junctiva.
Never infects cornea.
Occurs in boyhood, especially in hypernie-
tropes, and treatment consists in correction
of refractive error.
Trachoma.
Slight redness and irritation of eyes.
Follicles commonly in upper as well as lower
fornix, and always on palpebral conjunc-
tiva.
Scattered irregularly.
Always followed by scarring.
Commonly causes a gelatinous infiltration of
upper part of cornea, so called "pannus."
Generally in adolesence and in aliens,
especially Jews.
Trachoma may cause great diminution in A^ision, when pannus is
present, and the subsequent cicatrisation in the conjunctiva predisposes to
entropion and ectropion of the lids, and various other sequelae of a per-
manent character.
The great distinction between follicular conjunctivitis and trachoma is
that the latter always affects the palpebral conjunctiva of upper lid, and the
former never. In doubtful cases the upper lid should be everted and follicles
looked for.
Plate I.
^.-TRACHOMA AND PAN N US.
Note. Irregularly placed follicles on fornix and pal(>ebral conjunctiva. Gelatinous
inBUration of upper part of cornea (pannus).
B.- FOLLICULAR CONJUNCTIVITIS.
Note. Follicles in rows on fornix, the palpebral conjunctiva being free. Cornea clear.
C.-FHLYCTENULAR CONJUNCTIVITIS.
.Vote. Three phlyctenes are shown, the redness being chiefly around them, other parts of
the conjunctiva being free from injection.
)._ANGULAR CONJUNCTIVITIS.
Note. The redness is confined to the inner and outer angles of the eye.
THE EYELIDS AND CONJUNCTIVA.
47
Conjunctivitis Eczematosa or Phlyctenular Conjunctivitis occurs in child-
hood, and photophobia (intolerance to light) is one of the characteristics of
this disease. So intense is it that occasionally the child creeps into a dark
corner of the room, and strenuously resists any attempt made to open it
eyes. The intensity of the symptoms bears an inverse ratio to the severity
of the disease, the slighter the case the severer the symptoms. In its
simplest form it presents the following picture : A little red swelling, about
the size of a millet seed, develops generally at the corneal margin (limbus
conjunctivae). At first it is conical, and epithelium covers its apex, but
later this breaks down, and a small ulcer is formed. The reddened portion
of the conjunctiva is in the shape of a triangular sector, with its apex at
the nodule. The remainder of the conjunctiva is normal. Frequently
there are several nodules appearing at the same time, and often they form
on the cornea. Acne of the conjunctiva and episcleritis are the only condi-
tions likely to be confused with this disease.
Pinguecula. ^The atmospheric influences (wind, dust, etc.) produce
changes in that portion of the conjunctiva exposed to them. This area is
called the inter-palpebral part, and in elderly people a thickening of the
conjunctival tissue is sometimes noted here. This thickening often assumes
a yellowish colour, . largely due to the formation of numerous concretions of
a yellowish hyaline substance, and is called a pinguecula. As a result of
these changes, the pinguecula does not allow the red colour oF the blood to
shine through as plainly as the non-thickened adjacent conjunctiva, and it
might be confounded with a small pustule by a beginner. No symptoms are
caused, and treatment is rarely indicated.
Fiif. 24.
Pterygium.
Pterygium. This is a pocnliar growth of the conjunctiva and sub-
conjunctival tissue. Triangulai- in shaix', with its base (.^o-called body) at
the semilunar fold, close to the inner canthus, it extends outwards, tapering
to a rounded end (called the head), which gradually spreads on to the cornea,
and becomes solidly and immovably united to it. In recent and progressive
48 THE EYICLIDS AM) CONJUNCTIVA.
case^ the pterygium is red, flesliy and prominent, but in regres.sivii ones it is
pale, membraneous and almost translucent. It rarely spreads beyond the
centre of the cornea. Generally it affects patients about middle age. A
pterygium probably originates from a pinguecula, the degenerative procesfi
which exists there making its way into the limbus, and then gradually upon
the cornea itself. The treatment is surgical, and consists in thorougli
removal.
Lipoma (fatty tumour of eye). This occurs at the outer part of the
eye, and is congenital in origin. It appears as a solid, fatty-looking an<l
ill-defined growth, and when large surgical treatment should be resort^^d to.
Fig' ^S'
Subconjunctival Lipoma.
The eye is strong!}- adducted, to bring the tumour into prominence.
INJURIES OF CONJUNCTIVA.
Sub-con junctival haemorrhage may arise from a blow on the eye, an
attack of coughing, or over-exertion. The blood appears as a bright red
mark strictly limited tb a portion of the conjunctiva. It is of only slight
significance, and causes no symptoms, but the vivid redness may unneces-
sarily alarm the patient. Its dispersion is aided by hot fomentations, an<l
generally takes two or three weeks.
In fractures of the skull, involving the orbital plate, a large sub-
conjunctival haemorrhage appears, but its upper margin cannot be defined.
Such cases should always be at once referred to a medical man.
Foreign Bodies on the Cornea, or on the Conjunctiva lininij the Lids.
Small-sized foreign bodies, as grains of dust, particles of coal or ashes, first
fall upon the surface of the eyeball, and are brushed aAAay by movements
of the upper lid, generally sticking to its inner surface near the lid border,
where there is a small furrow the sulcus subtarsalis in which the foreign
body lodges.
THE EYELIDS AND CONJUNCTIVA. 49
Then- is i^veat irritability of the eye, accompanied by a copious flow of
tears, an inability to raise the upper eyelid and face the light, and a
distinct feeling of grittiness, as if something were in the eye. The sudden-
ness of the attack, and the exposure to which the eye has been subjected
are points to be noted, but confirmation can be sought only in the detection
of the foreign body, as many acute inflammatory conditions commence in
a similar n)}injier.
The cornea should be carefully examined by focal illumination, and if
the foreign bmly is detected there, an attempt should be made to remove it,
using the hem of a handkerchief or a blunt-pointed instrument. If unable
to displace the body, it is wiser to refer the case to an oculist, as, being
imbedded in the cornea, it necessitates the instillation of cocaine and the
use of a sharp-pointed instrument ere it is dislodged. The chief danger in
using the latter is not that of entering the anterior chamber, but of intro-
ducing sepsis, and causing a septic ulcer.
If a foreign body is not detected, then the lower lid should be
everted by placing the tip of the thumb or finger on the loAver margin of the
lid and drawing it well downward. This allows observation of the lower
fornix. The patient is now asked to look up, and at the same time the
thumb is pushed backwards over the rim of the bony socket, so everting the
lid and bringing the palpebral conjunctiva well into view.
If a fort'ign body is not present, then the upper 'id should be everted.
This is more difficult than eversion of the lower one, especially in small
yes an<l where there are projecting brows. It is essential for its success
that the patient not only looks down, but continues looking down until the
lid is everted ; and in his instinctive tendency to look up, when any traction
is made on the lid, lies the main reason of failure.
In examining an eye in which a foreign body is suspected to be lodged,
place the patient in a good light. First examine carefully the cornea, then
the lower lid and fornix, and lastly the upper lid and fornix. The symp-
toms are immetliately relieved on removal of the foreign body, except in
those cases in which it is imbedded in the cornea.
Methods of Everting the Eyelids.
The following is a detailed description of methods of inversion :
You may stand either behind or in front of your patient. Direct him
to look down, and seize, between the forefinger and thumb (using right to
light eye, and left to left eye), the upper lashes, at their attachment to the
lid, drawing them gently away from the eyeball (Fig. 26). At the same
time, with the other hand, place some blunt instrument (match, end of pen.
50 THE EYELIDS AND CONJUNCTIVA.
or tip of finger) above the upper edge of the tarsal cartilage, and whilst
exerting pressure downwards with this, pull upwards on the lashes, thus
everting the lid over the match, using the latter as the fulcrum. The
finger then, by gentle pressure on the everted lid, maintains it in position
until the foreign body is removed.
Occasionally the foreign body is situated in the upper fornix, and to
expose that it is first necessary to evert the upper lid, and then push up the
lower lid under the lower edge of the upper inverted lid, so further inverting
it. The patient must be looking downwards as far as possible to render this
manoeuvre successful.
Ftg. 26
Showing: method of evening the upper lid with a match.
The best method of everting a lid is performed solely by the fingers
(using right hand to left eye, and left to right ej^e), as not only can both
lids be everted simultaneously, but the tendency of a patient to look up so
fatal to a successful eversion is greatly minimised. To do this, stand
before patient ; place tip of thumb on the centre of lower lid, and push the
latter slightly up, whilst asking the patient to look up. Now tell patient
to look down, and at the same time raise the upper lid slightly from the
eyeball by tip of finger placed above upper edge of tarsal cartilage, and you
will notice that the upper lid falls gently over the lower. Whilst pressing
slightly downwards and backwards with the forefinger on the upper lid,
you evert it by pressing the lower lid upwards again'^t the inner and
marginal surface of the upper, using the lower as the fulcrum. Very little
practice is necessary to becomo accomplished in everting the lid in this
manner, and when such has been gained, the method offers the easiest, and
to the patient the least disagreeable, procedure.
THE EYELIDS AND CONJUNCTIVA.
EvERSiON OF Lids by Fingers alone. -
51
The lower lid is pushed up by thumb, whilst patient is looking^ upwards.
Fig. 2H
Shows upper lid lyinjj over marginal part ot lower.
Fi^. 2g
Everted upper and lower lids
52
THE LACHRYMAL APPARATUS.
Chapter IV.
ANATOMY.
The lachrymal organs consist of the lachrymal glands and the lachrymal
passages. The principal lachrymal gland lies in a depression sitnated at
the outer angle of the orbit, upon the under surface of the upper bony
orbital wall, but there are smaller ones beneath the conjunctiva of the
fornix, situated towards the inner angle. The lachrymal passages are
conveniently divided into three parts (a) the canaliculi, (h) the lachrymal
sac, (c) the nasal duct.
TL
Fig. JO.
Dissection of the Lachi yiiial Apparatus.
C Canaliculi. D Duct. G Glands. S Lachrymal sac. P Puneta. Ts & Ti Superior
and inferior tarsi.
The gland secretion empties itself into the outer half of the upper con-
junctival fornix, and the tears flow across the eyeball, and escape into the
lachrymal passages through two minute openings one in either lid
stationed on their margins near the canthus, and termed +he puneta
lachrymalia. Each punctum is in apposition with the eyeball, and can
only be seen on slightly everting the lid margin. The pui^cta are situated
upon small elevations, and they open into the lachrymal canals or canaliculi.
The upper canaliculus runs upwards, and the lower downwards for a short
distance, and then they bend at right angles and become directed towards
the lachrymal sac, converging more and more as they approach the sac,
and opening into the latter either separately, or after having united to
form a short common canal.
THE LACHRYMAL APPARATUS. 53
The lacliryinal sue lies in the inner angle of the eye, beneath the
internal tarsal ligament. The latter can be distinctly felt, when the eye is
turne^J outwaixls, as a tense band beneath the skin, and it forms a most
important guide to the sac. The sac is a membranous bag measuring
about 2 in. in length, and is capable of great distension. Its summit is
blind, and reaches a little above the level of the tarsal ligament, whilst
inferiorly it opens by a somewhat constricted orifice into the nasal duet.
The nasal duct is about J in. long, and opens into the lower part of the
nose, called the inferior meatus.
The mucous membrane of the lachrymal sac and that of the duct form
one continuous whole, there being no sharp dividing line between them,
but the duct lies in an osseous channel -being completely surrounded by
bone and so cannot become distended, whilst the sac has no bony sur-
roundings in front, and distension rea<lily takes place when the duct is
obstructed. The tears consist of water, with a slight admixture of sodium
chloride (common salt). Normally, except under the influence of emotion,
the secretion is only just sufficient for lubricating purposes, and so tears
are not constantly dripping into the nose. Some uncertainty prevails as to
the factors most important in the excretion of tears, but the act of
winking, together with the movements of the eyeball, serve to carry them
across to the inner side, whence, for their removal into the canaliculus,
correct adaptation of the puncta to the globe is indispensable. The
lachrymal sac has in front of it the internal tarsal ligament, and behind it
a small muscular layer derived from the orbicularis muscle, called Horner's
muscle, and it is generally thought that the entry of tears into the
oanaliculi is facilitated by compression of the sac between the ligament and
the muscle, thus producing suction, but in any case the rate of outflow is
only slight, and if tears be secreted in any quantity they overflow on to the
cheek.
AFFECTIONS OF THE LACHRYMAL APPARATUS.
These are manifested by an overflow of tears, which, when causetl by
over-production, is called lachrymation, and when due to interference with
the outflow of tears is named epiphora.
Lachrymaiion is an actual hypersection of tears, which escape on to
the cheek owing to the rapidity with which they are secreted, and occurs in
many eye conditions, especially affections of the cornea, and to a less extent
those of the conjunctiva, iris, ciliary body and retina. Lachrymation is
also a prominent symptom in some nasal affections.
Epiphora expresses an overflow of tears caused by some imperfec-
ti)n in the excretory part of the lachrymal apparatus, and this in
turn causes the escape of tears to be interfere<l with. They then accumulate
at the inner angle of the eye, and from time to time escape on to the cheek.
The epiphora is aggravated by exposure of the eye to cold or wind, which
cause an increase<l prmluction of tears.
54 THE LACHRYMAL APPARATUS.
Epiphora may arise from :
(1) A displacement of the punctum, without any mechanical obstructioo
in the canaliculus, lachrymal sac or nasal duct. In old people the lower lid
frequently falls slightly away from the eyeball, owing to a diminished tone
of the orbicularis muscle, and then the punctum does not lie in apposition
to the globe. In ectropion a further displacement of the punctum is
present, whilst in entropion an inversion of the punctum prevents the tears
from escaping into the cnnaliculus. In these cases the cause of the epiphora
is at once evident, and treatment consists in placing the punctum in proper
position against the eyeball.
(2) Obstruction of the canaliculus. It may then be due to a foreign
body, as a chalky concretion from the tears, or to closure of the lumen (or
open passage) as the result of inflammation. In these cases it will be noted
that the punctum is in place, and, further, that on pressure being applied
over the lachrymal sac no return of the tears into the eye via the canaliculi
is obtained, which would be the case if the canaliculi were patent, and there
was an obstruction in tlie sac or below it.
(3) Obstruction in the lachrymal sac or nasal duct.-^In the early
stages no dilatation of the sac is noticeable, but on pressure over the sac
(the patient turns the eye out, and pressure is applied firmly over the
internal tarsal ligament) the lachrymal fluid is forced back into the eye, as
the obstruction in the duct prevents its escape into the nose.
In the later stages the lachrymal sac becomes distended, owing to the
continual accumulation of tears, and the distension appears externally as
an elongated oval swelling, situated between the inner angle of the eye arid
the nose, chiefly below the level of the tarsal ligament. This condition is
called a mucocele, and on pressure over it, the ( ontents, consisting chiefly of
muco-pus, are squeezed back into the eye. The muco-pnrulent character of
the fluid is owing to the tears, when stagnated in fhe sac, being a good
medium for the growth of microbes.
Treatment in the early stages consists in syringing and probing the sac
and duct, but later, when a mucocele has developed, only excision of the sac
provides permanent relief.
A not uncommon cause of epiphora is an improperly fitting pince-nez,
the plaquets, by undue pressure on the skin, occasioning a slight separation
of the lower punctum from the globe.
55
THE CORNEA.
Chahtkr v.
ANATOMY.
The (tornea, together with the sclera, represents the outer fibrous
envelope of the eyeball, the cornea constituting the tranvsparent portion.
It has the form of a horizontal ellipse, the horizontal diameter averaging
twelve millimetres and the vertical eleven millimetres. It is thickest at the
periphery (about I mm.), and thinnest in the centre, and is inserted into the
sclera like a watch glass, its posterior layers extending further into the
sclera than the anterior ones. The cornea is non-vascular, but permeated
by lymph channels, and the nutriment enters it from the network of vessels
around the margin, and probably also from the anterior chamber.
Cross-section through cornea, magnified 70 diameters.
E Anterior epithelium. B Bowman's membrane. 5" Stroma, composed of lamellae (L)
and corpuscles iK). D Discemet's m< mhrane. E Posterior epi h .Hum. N Nerves
extendini; through Bowman's membrane and epithelium.
The cornea is richly supplied with nerves from the ciliary and con-
junctival plexuses, which ramify very extensively in the superficial layers,
and also penetrate the epithelium, so accovnting for its extreme sensibility ^
and the severe pain accompanying superficial corneal abrasions.
56 THE CORNEA.
The cornea consists of the following layers from before backwards:
(1) Several layers of transitional epithelium, the most superficial being
more flattened than the otliers.
(2) Boictnan's membrane, a delicate homogeneous substance, which is
really only the upper part of the next (or third) layer.
(3) Substantia propria, or corneal substance proper, consisting of
bundles of fine connective tissue arranged in well-defined lamellae,
and united by cross fibres. Between the bundles are the above-
mentioned lymph channels, in which lie large flat branching cells
the corneal corpuscles.
('4) DescemeV s membrane, a homogeneous elastic membrane, the product
of the endothelial cells covering its posterior surface. It is very
tough, and offers great resistance in cases of destructive ulceration
of the cornea.
(5) A layer of flattened cells continuous with the epithelium covering
the iris.
The cornea is transparent in iiealth, and all pathological changes cavise
a diminution of this transparency. In old age it becomes duller, its
refractive index is increased, and often a narroA'r, greyish line, called the
arcus senilis, appears near to and concentric with the margin. This
generally begins at the upper and lower margins, and gradually grows
round it, the outer edge being clearly cut and separated from the con-
junctiva by a slight portion of clear cornea, but the inner edge shelves
gradually into the clear cornea. The arcrs senilis is formed by tlie deposi-
tion of hyaline masses and minute particles of lime m the superficial layers
of the cornea.
Clinical Examination of the Cornea. A gocd light and fecal illumina-
tion must be used, and a poAverful pocket lens is essential, in order to
detect finer changes. The following points should be noted :
(1) The size and form of the cornea. Both may be altered congenitally
or by pathological changes.
(2) The surface of the cornea should be noted w^th regard to its curva-
ture, smoothness and polish. If the patient's eye is d'rccted so that the
reflection of a window placed opposite is visible on the cornea, then move-
ment cf the eye will cause the reflection to fall upon different portions, and
we see the reflex image becoming larger or smaller, according to the varying
curvature. When the polish of the surface is lost, it appears dull, like
glass which has been breathed upon. This condition is noted in acute attacks
of glaucoma.
(3) The transparency of the cornea. Dense opacities are noticeable
from a distance, but to detect the slighter ones focal illumination^ and
sometimes even a magnifying glass, are necessary. A slight opacity of the
cornea is one of the most commonly overlooked pathological changes, and it
should alwavs be excluded in cases of diminished visual acuity.
THE CORNEA.
A
Keratitis punctata. In A the depo>its are arranged in the form of a triangle, the larger
ones being below. B Represents the "mutton fat" form.
In inflammation of the ciliary body (cyclitis) there is a deposit upon
the back of the cornea of spots of pigment, circular in shape, and often
arranged in a pyramidal manner, with the apex about the centre of the
cornea, but sometimes the arrangement is irregular. The name " keratitis
punctata " (K.P.) is given to this condition. The spots are migratory
pigment cells from an inflamed ciliary body, and they can only be seen with
a corneal lens and focal illumination.
The details oi a corneal condition can be well seen by examining it Avitli
the small ophthalmoscopic mirror with a + 30 D behind. First we fix the
surface of the cornea, rendered evident by the slight particles of dust
floating on it, and then gradually approach nearer the eye until the details
ot the iris are clearly seen. In this manner the various parts of the cornea
are successively examined.
AFFECTIONS OF THE CORNEA.
Keratitis is an inflammatory condition of the cornea, and an important
distinction is made between superficial and deep keratitis, using the terms
not in relationship to the depth they may extend into the cornea, but only
in relationship to their arterial supply ; for instance, the blood vessels in
superficial keratitis are derived from the conjunctival vessels around the
margin of the cornea, the normal cornea being avascular, whilst in deep
keratitis they are derived from the ciliary vessels around the limbus.
Every keratitis is manifested by a loss of lustre and transparency in
that portion of the cornea affected, and is accompanied by inflammatory
signs in adjacent tissues.
(1) Increased redness of the eyeball, which is most marked around the
corneal margin, as it is a ciliary injection (see conjunctivitis for the
difference between ciliary and conjunctival injection). The degree of injec-
tion bears a direct ratio to the severity of the inflammation. In slight
cases it is difficult of detection, whilst in severe ones the injection is not
only ciliary, but conjunctival as well, and the globe appears a vivid red.
(2) In the slight cases we jget a hypersemia of the iris, and a contraction
of the pupil; but in deep keratitis, iritis and iridocyclitis often supervene.
s
THE CORNEA.
Diagrammatic section of the cornea showing new vessels.
A Superficial corneal vessels. These are sinuous, and continue unbroken on to the
conjunctiva. They branch and anastomose with one another. B Si, C Deep corneal
vessels. These disappear at the corneal margin, do not branch, and pursue a fairly
straight course.
The signs which enable ns to distinguish the two kinds of blood v^sek
are as follows :
Superficial vessels.
Thesti spring from the network of con-
junctival vessels near the limbus,
and can be traced directly into the
conjunctival vessels.
Owing to their superficial position they
are clearl}' visible, well defined, and
of a vivid red color.
The vessels branch
manner.
The abiwe is seen ii
afh arborescent
Deep vessels.
These spring from the ciliary vessels
in the sclera, clo>e to ih ; corneal
margin, and so appear to suddenly
end at the limbus, disappearing
behind it to enter the sclera.
They are not distinct, owing to cloudy
layers of cornea lying in front of
them, and are of a dirty red hue.
The vessels form fine straight twigs.
The above is seen in interstitial kera-
titis.
(3) A white exudate appears in the anterior chamber, and is called a
hypopyon, but it is only evident in severe cases. This exudate, appearing like
pus, lies at the bottom of the anterior chamber, and consists of leucocytes
(white blood cells, or scavengers), which have escaped from the blood vessels
of the iris and ciliary body.
There are two important sub-divisions of keratitis :
(1) Non-ulcerative or non-suppurativc , in wliich the corneal epithelium
remains intact, and where the inflammation does not result in the formation
of pus In these conditions a complete restoration of the transparency of
the cornea may take place, and normal vision be regained.
(2) Ulcerative or suppurative keratitis. The corneal layers and
epithelium are destroyed over the portion of the cornea infected, and an
ulcer is formed. All ulcerative conditions, wherever in the body situated,
heal by the formation of fibrous tissue. This is opaque, and so a return to
the natural transparency of the cornea is impossible. The degree of
opacity ultimately remaining depends largely on the depth of the ulcer and
the age of the patient the deeper the ulcer the greater the opacity, and
the younger the patient the more it tends to clear up. Bot>i ulcerative and
non-ulcerative keratitis may be situated superficially oi deeply.
(a) Superficial forms of non-ulcerative keratitis.
Pannus. This is the most common form of superficial keratitis, and is
reallj' an affection of the conjunctival layer of the cornea (the corneal
THE CORNEA. 59
epithelium). It may be caused by trachoma, in which case the disease
affects the upper part of the cornea, or by phlyctenular conjunctivitis,
when any part of the cornea may be attacked.
Trachomatous pannus (Plate I.) begins at the upper part of the cornea,
and consists in the deposition, beneath the corneal epithelium, of a newly-
formed, brownish, vascular tissue, which pushes its way from the edge to
the centre of the cornea. It appears as a grey, translucent, gelatinous,
and superficially-situated, cloudy mass, traversed by numerous blood
vessels. These are derived from the conjunctival vessels, and have
the distinctive features as previously described. The pannus rarely spreads
below the centre of the cornea. In very severe cases it may develop at other
portions of the corneal margins, and so completely envelop the cornea.
Though in slight cases the condition may clear up, leaving the cornea
transparent, yet the newly-formed tissue is frequently partly transformed
into fibrous tissue, which appears as a dirty greyish opacity, limited to the
upper part of the cornea, with conjunctival vessels ramifying in it.
Pannus eczeinatosus. This is due to phlyctenular conjunctivitis, and is
differentiated from trachomatous pannus by its being situated in any
portion of the cornea. Also an examination of the lids reveals the absence
of trachoma.
Keratitis vesiculosa. The formation of small .clear vesicles on the
surface of the cornea is distinctive of this affection, and it is often associated
with neuralgia of the supra-orbital nerve. The vesicles themselves are
rarely seen, as their walls consist only of the corneal epithelial layer, and
pressure of the lids quickly ruptures them, only a tag of corneal epithelium
being noticed. A tendency to frequent recurrences is characteristic of this
affection.
(6) Deep Keratitis. In these conditions the infiltrate develops in the
middle and deep layers of the cornea, and they are often accompanied by
inflammation of the uveal tract (the ciliary body and iris). The only common
variety of deep keratitis is
Interstitial or parenchymatous keratitis. It is a disease of youth,
generally appearing between the sixth and twenty-first year, and is nearly
always caused by congenital syphilis. Tubercular tendencies are also sug-
gested as a causal factor. In congenital syphilis the teeth are abnormally
shaped. They -aw jx'^-shaped, and the upper incisor teeth show a deep
semi-lunar indentation, and are called "Hutchinson's teeth." These changes
exist only in those of the second dentition.
^'S' 34-
Teeth in conf^cnital syphilis.
(Hutchinson '. Teeth. )
6o
THF CORNKA.
There may be slight pain in th(' eye, but photophobia and lachryma-
tion are often the only symptoms. Sometimes the disease begins
in the centre of the cornea, and at other times at the periphery, but
it invariably affects both eyes, first one and then the other. It commences
as a diffuse haziness, either centrally or peripherally, accompanied by
ciliary injection. The lustre of the cornea is lost over the area attacked.
Deep blood vessels (Fig. 33) grow in from the margin, and the haziness
gradually spreads, until sometimes the whole of the cornea becomes opaque.
Great variations exist with regard to the density and extent of the infiltra-
tion, and generally the worst cases are those which commence in the centre
of the cornea. Variations also exist with regard to the number of blood
vessels present ; in many cases they are so abundant that the cornea presents
an appearance like red cloth, whilst in others they are so scarce that the
condition appears like white ground glass.
H^' 35-
Infiltrate in the cornea.
The Epithelium {E) and Bowman's membrane {B) over the infiltrate, are preserved.
The great variations in the clinical picture of parenchymatous keratitis
offer difficulties to the beginner, but one must bear in mind that it never
forms an ulcer the corneal epithelium always being intact and that the
blood vessels are derived from the ciliary vessels. In this condition,
especially in the more severe types, we get an accompanying inflammation
of the iris, ciliary body and choroid. The outlook in this disease is
unfavourable in the severe cases, as marked diminution of visual acuity
generally persists, but in the milder forms vision is only slightly reduced,
the cornea becoming more or less transparent again. It is always chronic in
its course, averaging about nine months.
Other uncommon forms of deep keratitis are sclerosing keratitis and
keratitis profunda.
Ulcerative keratitis. In these cases there is an infiltrate, situated
superficially in the cornea, which rapidly spreads and forms pus. It
breaks through the corneal epithelium, and in this way a superficial Joss of
substance is produced, resulting in the formation of an ulcer, recognisable
as a depression on the corneal surface. An ulcer is stated to exist when
there is a discontinuity of the corneal epithelium.
THE CORNEA. 6f
The symptoms are, great pain, especially on movement of the lids (the
patient often assuming that it is only a foreign body in the eye), lachryma-
tion and photophobia. The severity of the symptoms bears a direct ratio to
the severity of the disease.
The eyeball appears reddened owing to conjunctival and ciliary injection,
and, in the severe cases, the bulbar conjunctiva becomes swollen. This condi-
tion is called chemosis of the conjunctiva. Over the superficially disposed
infiltrate in the cornea, tlie surface is dull and the cornea cloudy. Then the
epithelium over this breaks down, thus creating an ulcer. This is sur-
rounded by infiltrated portions of the cornea (recognised by the grayness of
the base and walls of the ulcer), which in severe cases continues to spread
both deeply and peripherally, at the same time breaking down, and so
making the ulcer both larger and deeper. In some cases this extends as
far as Descemet's membrane, which, owing to its great resistive powers, is
protruded by the intra-ocular pressure, appearing as a transparent vesicle
at the base of the ulcer. This is called a keratocele. Later the vesicle
may rupture, and then a perforation of the cornea occurs^ resulting in the
escape of the aqueous tumor through the perforation. The anterior
chamber being obliterated, the iris and lens, in the region of the pupil,
are applied to the posterior layer of the cornea.
When an ulcer is extending, we speak of it as in the progressive stage.
This is recognised clinically by a gradually increased extension of the
infiltrated area, and by greater ciliary and conjunctival injection, and, more-
over, inflammation of the ins may later make its api)ea ranee, as evidence<l
by turbidity of the aqueous, hypopyon (white exudate lying at the bottom of
the anlerior chamber), contracted pupil, posterior synechia;, and discoloura-
tion of the iris. "VMien the infiltration ceases to spread, the ulcer entering
upon its regressive stage, cleanses itself, and the surrounding infiltration
disappears, leaving a glistening base and clear sides, the symptoms
gradually disappearing. After the ulcer has become entirely clean, cicatrisa-
tion commences. Blood vessels grow in from the nearest portion of the
limbus (corneal margin), carrying pabulum and new cells, and the base of
the ulcer again becomes clouded, but at the same time shallower, until
finally it reaches the level of the adjacent normal cornea. Sometimes it
does not quite reach that level, being discernible as a facet, or, oAving to
the diminished resistance of the cicatrix, the latter may be bulged forwards,
so called ectatic cicatrix
^t^' .76.
Staphyloma of cornea.
The whole cornr.i has hem destroyed, and / represents the cicatrised iris. P The pupil,
now filled in with cicatricial t.ssue. B The posterior chambt- r. L The lens. C Remains
of cornea.
62 THE CORNEA.
Where, in perforating ulcers, the larger portion of the cornea is
destroyed, the iris becomes applied to the narrow remaining corneal rim,
and the pupil and iris become covered by exudate, which later is trans-
formed into fibrous tissue. So the anterior portion of the eye in these cases
is formed by the cicatrised iris, no anterior chamber, of course, being
present, but behind the iris lies the posterior chamber and lens. In these
cases the scar generally bulges forwards, owing to its resistive power being
less than that of the normal cornea, and this condition is called "staphyloma
cornese."
Corneal ulcers are due to infection of the cornea by microbes, and the
greater their toxicity, the severer the ulceration. As only a few microbes,
viz., gonococcus, diphtheria bacillus, etc., can attack an uninjured cornea,
the majority of ulcerations follow abrasions of the cornea, which allow of
entrance of the microbes. The prognosis, or outlook, depends upon the
density of the scar and its relationship to the pupil. The younger the
patient, the greater the absorption of the cicatrix.
Treatment. In the progressive stages, hot antiseptic fomentations and
the instillation of atropine are necessary. A pad and bandage is worn to
prevent the friction of the lids. To reduce the density of the cicatrix,
irritating ointments and lotions are introduced into the eye.
^^S' 37-
Dendritic ulcer, characterized by its arborescent shape.
Varieties of Ulcer.
Dendritis ulcers, so called from their shape like the branches of a tree,
often with nodular swellings at the extremities of the branches are only
superficial, but give rise to intense pain, and are of frequent recurrence.
Bodent ulcer. A superficial ulcer, gradually spreading, with inter-
vening remissions of apparent recovery, over the whole of the cornea. The
spreading margin is undermined, and, if destroyed by the cautery, a cure is
attained.
Ulcus serpens. A severe ulceration, commencing in the centre of the
cornea. It is discoid in shape, the opacity being more marked at the
periphery than at the edge. It causes hypopyon and iritis, and often
results in perforation of the cornea. It is caused by the pneumococcus
organism, and is often associated with the presence of dacrocystitis. The
prognosis is bad, perforation of the cornea being a frequent sequel, and
even when the eye is saved, the central dense opacity greatly reduces vision.
THE CORNEA. 63
INJURIES OF THE CORNEA.
(1) Foreign Bodies. It is not uncommon for blacksmiths and iron-
founders to have particles of hot iron or st^el flying into the eye, and
travellers by rail or road may have a piece of grit blown upon the surface
of the cornea. A sudden onset of acute pain, greatly increased upon move-
ment of the lids, photophobia and lachrymation are the chief symptoms,
but they are not characteristic of a foreign body, as many corneal affections
exhibit the same indications and rapidity of attack. On inspection of the
eye, ciliary and conjunctival redness will be noted, but confirmation of the
diagnosis lies only in the detection of the foreign body on the cornea. So
minute are many of these extraneous particles that they may only be dis-
covered after careful search with the aid of a corneal loupe and focal
illumination. The foreign body may be imbedded and this is usual with
hot iron particles^ or it may lie on the surface of the cornea. In the latter
case its removal is easy of accomplishment by the aid of a blunt instrument,
as a spud, or the hem of a handkerchief. If imbedded in the cornea, the
case should be referred to a surgeon, as the instillation of cocaine and the
use of a sharp-pointed instrument are necessary ere the bodj^ is dislodged.
(2) Abrasions of the Cornea caused by scratching the eye with finger-
nail (commonly found in mothers, due to baby poking its fingers in her
eyes), or a stiff leaf or twig. It is followed by well-marked symptoms of
irritation and violent pain on movement of lids. The slight loss of
epithelium can be detected by observing the corneal reflex or by instilling
into the eye fluorescin, which stains the abraded area a greenish hue.
Treatment consists in the application of a pad and bandage, using sufficient
pressure to prevent movement of the eyeball. Deeper wounds of the cornea
may be straight or lacerated, and may extend through part or the whole of
the cornea.
Burns hy Caustics. Hot water, steam, molten lead and lime are the
most common agents. They cause inflammation and ulceration of the cornea.
In burns by lime, the eye should be washed out with a simple oil, and then
concentrated solution of sugar applied, this forming an insoluble compound
of lime. Prior to the application of the oil, any solid particles of lime that
may be visible should be removed, and the eye douched out with warm
water. The insoluble compound of lime has no deleterious effect.
Corneal Opacities. Opacities are generally the result of previous
corneal inflammation, with or without ulceration. Different nomenclature
is applietl to the slight forms from those of more severity. The former are
classed as maculse or nebulae, and the latter as leucoma.
(1) Nehulai or Maculoe. These are slight opacities, discernible only with
focal illumination, but cause much diminution of visual acuity when diffuse
in character and centrally situated. They appear punctate in shape, and
are bluish-white transparent spots, when view^ through a corneal loupe.
(2) Leucoma. This is a dense white opacity, and cannot be overlooked.
It may be raised above the level of the cornea, noticeably so in a recent
scar, and in the latter blood vessels will be detected, arising from the limbus
and permeating the leucoma. The character of the vessels will determine
whether the previous inflammation was superficial or deep. Occasionally
64 THE CORNEA.
the leucoma may be below the level of the cornea, causing the latter to be
flattened, and this condition is called " applantio corneae." The involvement
of the iris in the scar points to a previous perforation of the cornea, and
may be caused by an ulcer or the surgeon's knife; in the latter case the scar
will be linear in shape.
Fig. 38.
Zonular opacity of the cornea.
The disturbance of vision caused by opacities depends upon their
position and density. The denser the scar, the fewer the rays transmitted
through, and the more numerous are the reflected ones, but in the fainter
opacities the disturbance in vision is not caused so much by the diminished
transmission of the rays as by their irregular refraction, and, owing to this,
a slight opacity covering the whole causes more disturbance of vision than
a dense opacity, occupying only a portion of the pupillary area.
Where an irregular surface of the cornea has resulted from the cicitrisa-
tion, irregular astigmatism is present, and great interference with vision
results. The disturbance of vision produced by an opacity compels the
patient to bring minute objects close to his eye in order to obtain as large a
retinal image as possible, and so compensate him in a slight degree for their
indistinctness, and this habit increases the patient's liability to strabismus,
nystagmus and myopia.
In recent cases, irritating ointments and lotions introduced into the eye
increase the rate of absorption of the tissue, and the more vascular the scar
the better the results. In old avascular scars no benefit is derived from
such treatment, and attempts have been made, after excision of the nebula
by a trephine, to transplant either a portion of the cornea of the rabbit or
that of a recently extirpated human eye. This is always unsuccessful, as
the transplanted part invariably becomes opaque.
The refractive error must be corrected, and the wearing of a stenopaic
aperture is sometimes beneficial. The object of the latter is to exclude the
opaque area, by which means the dazzling due to irregular refraction is
prevented, only the transparent part of the cornea being brought into use
for vision. Unfortunately, the scar which lends itself to such treatment is
rarely encountered.
Displacement of the pupil, by excision of a small portion of the iris
opposite a clear part of the cornea, offers often the only means of restoring
vision in dense central opacities. Tattooing of the scar renders it less
noticeable, and in some cases an improvement in vision follows, but there is
a slight risk of introducing sepsis and causing cyclitis, however carefully
it is performed.
THE CORNEA. 65
Corneal opacities of non-inflammatory origin are the arcus senilis and
zonular opacity. The latter occurs sometimes in old age, and most frequently
in old blind eyes. It develops slowly, and commences on either side of the
lower part of the cornea, gradually growing inwards towards the centre,
and on examination with the corneal loupe it is found to be composed of
grayish-white dots, lying just underneath the epithelium. These give to the
surface of the cornea a roughened appearance, like shagreen.
Ectasia of the Cornea. This is a bulging forward of the cornea, and
may be of inflammatory or non-inflammatory origin
Non-inflammatory keratoconus or conical cornea ; keratoglobus.
Inflammatory Staphyloma ; kerat^ctasia.
Keratoconus or Conical Cornea. This consists of a bulging forwards of
the central portion of the cornea beyond its normal curvature, assuming the
form of an obtuse transparent cone. The periphery becomes more flattened,
and the central part gradually increases in curvature, rema.ning transparent
at first, but later, at the apex of the cone, a slight turbidity develops,
which becomes more manifest as the disease progresses. It commonly
<levelops about the age of fifteen to twenty, and is more frequent in young
women than men, but it is only rarely met with, the average at a large
London eye hospital being one in 7,000 patients. The condition usually
progresses for three or four years, and then remains stationary. Its
advancement is not regular, but periods of sudden increase, in some cases
as much as 3 D in a few weeks, followed by periods of quiescence, are
characteristic of this affection. In most cases both eyes are attacked, the
.second one considerably later, even a year or more, than the first.
The symptoms are diminished visual acuity, and perhaps asthenopia
may be complained of, the patient frequently volunteering the statement
that near vision is good. In the later stages the conicity may be noted with
the naked eye, by looking at the cornea from side to side, but not so ifi the
early period, and unless the eye is systematically objectively examine<l in
the routine method laid stress upon, the early stage of this disease maj' be
mistaken for regular myopic astigmatism. On examining the corneal
reflex, the corneal images will appear .small and perhaps regular in tlie
centre, but are displaced irregularly towards the periphery.
On transmitting light into the fundus, a characteristic appearance is
presented ; centrally a dull glow is observed, which peripherally becomes
considerably brighter, whilst between the two is a dark shadow of varying
breadth. On rotating the mirror the shadow always moves round the
centre of the pupil, never across it, no matter in which direction the mirror
is rotated. By rotating the mirror in the direction of the moving shadow,
that is circularly, a very characteristic appearance is presentetl, like a slow
moving Catherine wheel. In these cases no point of reversal is revealed,
and so retinoscopy does not help in determining the refractive error, but it
enables the true nature of the affection to be detected. Besides the circular
shadow, two others can frequently be discerned. In the periphery an
emmetropic or low myopic shadow may be seen, and centrally there i?
observed the ill-defined shadow met with in high compound myopic
astigmatism.
66 THE CORNEA.
Ophthalmoscopically the vessels of the optic disc and the disc itself
appear distorted, and the latter alters in shape and size, according to the
portion of the cornea we are looking through. By the keratometer the
reflected images are of various sizes, and cannot be brought into parallel
lineSj thus showing an irregular astigmatism of the cornea. There is a
period in the early stages of the affection when even careful objective
examination will only reveal some myopic astigmatism, and the true nature
of the affection will only be suspected at the patient's subsequent visit,
when an increase of the astigmatism will be revealed. This is always
suspicious, and examination of the patient at short intervals is advisable,
until time disproves or confirms one's suspicions.
Both naked eye and microscopical examination reveal a thinning of the
cornea over the cone, this increasing gradually from the periphery to the
apex, and at the latter a thin scar may represent all that remains of the
cornea. This never ruptures, but some observers think that it admits of
filtration of the aqueous, so accounting for the diminished ocular tension
occasionally met with.
Widely divergent and conflicting views are held Avith regard to the cause
of conical cornea, and, as these are purely theoretical, they merely demand
enumeration : (1) General malnutrition : (2) inherent weakness and deficient
firmness of the cornea ; (3) defective embryologicai development ; (4) chronic
disease of Descemet's membrane; (5) increased intra-ocular pressure.
That treatment cannot cure the condition is evident, and it is doubtful
whether non-operative treatment even retards its progress. Attention to
general health and abstention from Avork necessitating much use of eyes is
perhaps desirable, and also careful correction of the refractive error. Long-
continued instillation of eserine is favoured by some surgeons. In spite of
such treatment, the disease invariably progresses. Surgical treatment is
sometimes performed with the view of arresting its development, and this
aims at the substitution of a resistant cicatrix for the attenuated apex of
the cone. The latter is destroyed either by cautery or bj' excision. The
cicatrix, thus found, lies directly in front of the pupil, rendering necessary
its displacement to one side by means of a small iridectomy before any
acuity of vision is legained.
Keratoglohus. ^The cornea and the whole of the eyeball becomes
enlarged, and the condition is called bupthalmus, or ox's eye. It arises in
childhood, and is caused by increased intra-ocular pressure.
Ectasias of Inflammatory Origin.
Staphyloma of Cornea. This is a protuberant cicatrix, and is the result
of a perforation of the cornea, in which a large portion of the latter has
been destroyed. The iris then prolapses, and becomes covered with inflam-
matory exudation, which later cicatrises, and wholly or in part replaces the
cornea. The resistive power of the cicatrix is less than that of the normal
cornea, and hence bulging of the former takes place. A staphyloma may
include the whole of the cornea or only a part of it.
Keratectasia is a protrusion of the cornea, and occurs when the latter
has been weakened by a prior inflammation.
67
THE SCLERA.
Chapter VI.
ANATOMY.
The sclerotic invests the posterior five-sixths of the globe, and is composed
ot dense, pearly white, fibrous tissue, almost avascular in character, which
together with the cornea, forms the fibrous envelope of the eye, whose shape
is nearly that of a sphere, with a constriction at the corneo-scleral margin.
The sclera is thickest (about 1 mm.) posteriorly, and it gradually becomes
thinner anteriorly, tut the insertions of the recti muscles near the corneal
margin cause a slight increase in thickness in this region. The fibres of
connective tissue are united into bundles, which run in two main directions,
one from before backwards the meridional fibres and the other, concentric
with the cornea the circular or equatorial fibres. Lymph spaces, with
cells lining them, are found Ketween the bundles of fibres. The histological
structure of the sclera is thus something similar to that of the cornea, and
at the corneo-scleral junction the fibrous tissue of the sclera passes con-
tinuously into that of the cornea, its most superficial fibres being inserted
last of all. The two structures are dovetailed one into the other, and in
the deeper part of this junction is a circular canal called the canal of
Schlemra, which communicates externally with tlie scleral veins, and inter-
nally, through numerous small openings (ligamentum pectinatum), with the
aqueous humor in the anterior chamber.
The outei- surface of the sclera posteriorly is in contact with Tenon's
capsule, a lymph space intervening between the two, whilst anteriorly it is
covered by the conjunctiva, being separated from it by loose connective
tissue called episcleral or subconjunctival tissue. The tendons of the ocular
muscles are inserted into the sclera at varying distances (4 to 8 mm.) from
the corneo-scleral margin.
The following blood vessels piece the sclera to enter the eye (Fig. 43) :
(a) Anteriorly, near the corneal margin, the anterior ciliary vessels.
(6) About the equator, the venne vorticossp.
(c) Posteriorly, the long and short posterior ciliary arteries.
At the site of the optic nerve the sclera becomes split up into a network
of interlacing bundles, called the lamina cribrosa, leaving a series of fine
sieve-like apertures, through which the bundles of the optic nerve pass into
the eye.
68 THE SCLERA.
The sclera is only loosely attached to the sublying choroid by an irregular
raeshvvork of fine connective tissue, except at the sit/O of the optic nerve and
over the region of the ciliary muscle, and this network forms a considerable
lymph space called the perichoroidal space. The sclera, though traverse<l
by vessels and nerves, which penetrate into the interior of the eye, has of
itself very few vessels, and on account of this poor vascular supply it is
rarely the source of a primary acute inflammation.
PATHOLOGY.
Inflammation of the sclera is called scleritis, and that of the episclera
is known as episcleritis.
Episcleriiis. This is an inflammation of that loose connective tissue which
connects the sclera to the conjunctiva. It usually shows itself as an ill-
defined swelling on the outer side of the sclera, immediately behind the zone
corresponding to the ciliary body. Over the sweliinor the conjunctival
vessels are dilated, and also there is a deep-lying dusky or violet area, due
to congestion of the sclerotic coat. The former vessels move with the con-
junctiva, but not the latter. On palpation the swelling is felt to be hard
and nodular, and is very sensitive to the touch. Except at the site of the
nodule, the eye may be perfectly free from redness (injection). Over the
swelling there is often to be seen a translucent whitish patch, resembling a
conjunctival phlyctenule, and supposed to be due to some obstruction in the
lymphatic vessels.
The symptoms vary greatly ; often, only slight discomfort is complained
of, though occasionally very severe pain is present, depriving the patient of
sleep. Its onset is sudden, and its duration variable, often lasting from twO'
to five weeks, the nodule gradually flattening and becoming paler. Occa-
sionally it leaves no trace behind, though more frequently a slate- colon red
patch is left over the affected area, but otherwise the eye is normal.
Episcleritis is very liable to recur, often involving the entire circum-
corneal area before the disease exhausts itself. It is sometimes associated
with rheumatism, and treatment consists chiefly in the search for, and
eradication of, the cause, and the application of hot fomentations. Internal
remedies do not seem to have much influence on the affection.
Scleritis. This is an inflammation involving the sclera proper, and it
chiefly affects the ciliary region of the sclerotic. There is an ill-defined
swelling, accompanied by conjunctival injection, the sclera also showing
an extensive bluish-red injection. Both the swelling and redness are not so
localised as in episcleritis. The inflamed portion never forms an ulcer, but
the sclera is thinned, and no longer able to resist the normal intra-ocular
pressure, consequently a bulging appears over the site of the disease.
This is called an ectasia. In scleritis the deeper portions of the eye (the
iris, ciliary body and choroid) are also affected, so it is much more
serious than the superficial form (episcleritis). No special train of symp-
THE SCLERA. 69
toms other than objective signs can be ascribed to scleritis, but an ill-
defined swelling of a purplish, hue, outside the corneo-scleral margin, and
generally surrounding it, together with perhaps slight iritis and cyclitis,
form a clinical picture hardly likely to be confused with that of any other
disease.
The cause, like that of iritis and cyclitis, lies in the poisons produced
by microbes, and the treatment lies in its elimination, by attacking the
source of these poisons. Local treatment, as hot fomentations and atropine,
where iritis is present, is also applied.
Ectasia, or Staphyloma of the Sclera. This is a protrusion or bulging
of the sclera, involving either a portion of it (partial ectasia) or the
whole (total ectasia).
Partial Ectasia. This appears as a localised protrusion, of a bluish-
black colour, owing to the choroidal pigment shining through the attenuated
sclera. This is so thin over the area as to be readily dimpled by the point of
any blunt object, such as a match.
Various forms of ectasia, or staphyloma, are distinguished according to
their situation :
(a) Anterior or ciliary staphyloma.
(6) Equatorial staphyloma,
(c) Posterior staphyloma.
Anterior Staphyloma appears as a series of grape-like bulgings around
the ciliary region, the scleia being so thin as to admit of the pigment of the
ciliary processes being seen. This condition may be limit e<l to a part, or
involve the whole, of the sclera in that region.
Equatorial Staphyloma is a protrusion behind the ciliary region in the
neighbourhood of the equator of the eyeball. It is generally only noticed
when the eye is rotated strongly either inwards or outwards.
Posterior Staphyloma is a protrusion of the sclera at the posterior pole
of the eye, and is the most common cause of high myopia, owing to the
elongation of the eyeball along its sagittal axis.
Though the cornea and anterior half of the eye have attained their full
development ab(uit the fifth year, the eyeball does not reach its full siw
until about the seventeenth year of life (puberty). During the intervening
years the axial growth of the eye takes place solely behind the equator, by a
retrocession of the posterior pole, this continuing until the eyeball is of the
normal physiological dimensions (emmet ropia). Anything which tends to
diminish the resistive power of the young and comparatively soft sclera
will cause an excessive yielding of the unsupported posterior pole of the eye
before the normal intra-ocular pressure, and so produce an increased axial
length of the globe. The increased length (myopia) was supposed to be due
to the creation of an increased 'intra-ocular pressure, brought about by
exoessiye action of the external and internal eye muscles, this being greater
70 THE SCLERA.
than the coats of the eyeball could withstand. If this were so. the lamina
cribrosa, being the weakest spot in the eyeball, would be driven backwards,
as it is in glaucoma, but in myopia such never occurs, Henderson has
experimentally proved that under normal conditions the pressure within the
eyeball, and that within the optic nerve sheaths and brain, are exactly the
same under all ordinary conditions, and hence the lamina cribrosa has
normally to withstand no pressure at all, and so always preserves its
relationship to the adjacent coats. If, however, the intra-ocular pressure
be raised, as in glaucoma, the lamina cribrosa is pushed backwards, whilst
if the intra-cranial pressure be raise<l, as in brain tumor (choked disc), it is
pushed forwards.
Fig. -jg.
Diagram illustrating development of the myopic globe.
The anterior half is fully developed by the fifth year of life, but the axial length
is short, and so the eye is hypermetropic, though at the age of puberty the eye has
attained its normal axial length. If the posterior expansion occurs too rapidl}'
and excessively, myopia is produced. The lamina cribrosa retains its position, as
the pressure in the eye and brain ?.re equal.
CM Ciliary muscle. C Position for child of six years, A Adult, M Myope.
L Is the lamina cribrosa
In view of Henderson's experiments, it is more probable that myopia
arises from a less firm and weakened sclera being unable to withstand the
ordinary intra-ocular pressure, rather than due to an increased intra-ocular
pressure.
The limits of the posterior staphyloma can be often defined ophthalmo-
scopically, as at some distance from the papilla, running concentrically with
it, the retinal vessels will be seen by parallactic displacement to dip down
over the edge of the staphyloma.
7'
THE IRIS AND CILIARY BODY.
Chapter VII.
ANATOMY.
The iris arises from the anterior surface of the ciliary body, and is a
contractile diaphragm, dividing the space between the cornea and lens into
two, viz., the anterior and posterior, chambers. These are filled by the
aqueous fluid, the chambers communicating with each other by a central
aperture in the iris diaphragm, called the pupil. The iris is placed imme-
diately in front of the lens, its pupillary margin lying in actual contact
with the lens capsule, and so the posterior chamber is represented only by
the shallow space existing between the extra-pupillary portion of the iris
and the shelving peripheral surface of the lens. By lying upon the lens, the
iris obtains a firm support, and Avhen the former is absent, or has lost contact
with the iris, the latter is seen to tremble with movements of the eyeball.
The iris forms a shallow cone, whose apex, directed forwards, is represented
by the pupil, and the greater the advancement of the lens, the more promi-
nent is the cone, whilst, if the lens be retracted or absent, the iris appears
flat. In looking at the iris, either with the naked eye, or, better still, by
focal illumination, delicate markings (so-called patterns of the iris) will be
recognised. These are caused by elevations and depressions on its anterior
surface. In the normal eye they are well defined and clear, but in an
inflamed or atrophic iris they are blurred and indistinct, so forming an
important sign in iritic affections. The markings consist chiefly of pro-
jecting ridges, caused by the blood vessels in the stroma ri'diating from the
pupillary to the ciliary border. Near the pupillary margin a circular ridge
the circulus minor is seen, which divides the iris into two zones, a
Anterior surface of the iris, niaynifii'd six times.
P Pupillary zone. C Ciliary zone. R Fringe of retinal pigfment. A' Lesser drcle.
C Crypt. /" Contraction groove. N Naeviis. P Peripheral dark zone.
narrow pupillary, and a wide ciliary one. The former is of a different
colour from the latter, being generally lighter. Along the circulus minor,
depressions or crypts are easily observed, which are apertures leading into
the tissue of the iris, so allowing of free communication between it and the
anterior chamber.
72
THE IRIS AND CILIARY BODY.
The iris consists of a vascular and pigmented stroma of connective
tissue, containing also two sets of specialised fibres. Covering it
anteriorly is a layer of epithelial cells, continuous with those lining the
posterior surface of the cornea, whilst posteriorly the iris is lined by the
pigment epithelium, continuous with that covering the ciliary body, and
which extends as far forwards as the margin of the pupil. The pigmentary
membrane represents the continuation of the retina to its termination at
the pupillary margin, and consists of two layers, the anterior representing
the pigment epithelium of the retina, the posterior the retina proper. The
stroma of the iris consists chiefly of numerous vessels running from the
ciliary to the pupillary margin, and surrounding them is a network of
cellular tissue, in which many pigment cells are found. Also in the stroma
are two sets of specialised fibres, one being arranged concentrically around
the pupil, and consisting of a layer of unstripe<l muscular tissue forming
the sphincter of the pupil, whilst the other set consists of a layer of elastic
and muscular fibres radiating towards the periphery, forming the dilator
pupillse. Some authorities deny the existence of the muscular fihres in the
dilating apparatus of the iris.
The colour of the iris depends upon the amount of pigment in the
stroma, as that in the posterior laj^er is more or less constant. When the
stroma contains little, the retinal pigment shows through the thin iris, and
appears blue, just as a dark background always appears blue when viewed
through a more or less opaque medium. If the stroma is deficient in pigment,
but fairly thick and compact, the iris appears grey , whilst if pigment
abound in the stroma, then the iris appears broAvn. The iris is of unequal
bulk, being thickest at its periphery, where it forms a broad attachment to
Fio. ^i.
The ciliary region.
5' Sclerotic. C Cornea. A' Retina. Ch Choroid. / Iris. .s Canal of schlemm.
P Ciliary processes. M Longitudinal fibres of ciliary muscle. Mu Circular fibres of
ciliary muscle. L Lig-ainentinn pectinatum. A Circulus iridis major, SP Sphincter
pupillae. U Uveal pigment lining iris (broken away at U) and rounding edge at P.
CI Anterior ciliary vessels. O Flat portion of ciliary body. O Ora serratn. Z ^^
Zonule of Zinn. i Canal of Petit. /^^ Pc Layers farming the pars ciiiaris retinae.
the ciliary body, and here it is separated from the cornea by a rounded
space called the " angle of the anterior chamber." This space is traversed
THE IRIS AND CILIARY BODY.
73
by a loose-meshed stratum of connective tissue, known as the " ligamentum
pectinatum," which is supposed to arise from the splitting of Descemet's
membrane of the cornea. These meshes form a series of communicating
channels called the "spaces of Fontana," which, serve for the filtration of
the aqueous fluid, passing from the anterior chamber into a venous channel
or sinus, called the ** canal of Schlemm," situate<l between the cornea,
ciliary body and iris (Fig. 41).
The above views with regard to the angle of the anterior chamber have
recently been strongly controverted by Henderson, who says that
the ligamentum pectinatum iridis does not arise from the splitting up of
Descemet's membrane, and is not a ligament of the iris, nor does it
terminate in the root of the iris, but that it originates as a continuation of
the inner lamellae of the cornea, and for the most part forms the ligament
of origin of the ciliary muscle. He states that it is, at birth, a cellular
structure, which undergoes progressive sclerosis with advancing years, until
it becomes entirely fibrous.
The aqueous humor not only escapes by Schlemm's canal, but also
through the crypts of the iris into the iritic veins.
Fig. 42.
Blood ve.isels of iris and anterior part of choroid, viewed from the front.
A Anterior ciliary Hrteries. B Long cih'ary arteries. C Pupil. D Veins of choroid.
E Circiilus minor. F Lirculiis major.
The arterial supply of the iris is furnished by the ciliary arteries, some
of which run forward between the sclerotic and choroid, whilst others, the
anterior ciliary arteries, pierce the sclerotic close to the corneal margin.
74 THE IRIS AND CILIARY BODY.
To congestion of the latter is d^le the characteristic pink zone which sur-
rounds the cornea in inflammation of the iris and ciliary body (ciliary
congestion). Upon the iris the arteries form two arterial circles, the one
(circular iridis major) round the periphery, and the other (circulus iridis
minor) round the pupil ; the two being connected by numerous vessels
(Fig. 42).
The Ciliary Body is the continuation forwards of the retina and choroid.
Commencing at the line of the ora serrata (Fig. 41), it consists of an internal
deeply pigmented part, which is thrown into a series of radiating folds
(the ciliary processes), and an external non-pigmented pait, consisting of
unstriped muscle fibre (the ciliary muscle). The latter part forms the greater
portion of the ciliary body. The ciliary processes, about seventy in number,
radiate towards the lens, completely encircling it about the equator, being
separated from it by a space the circumlental space which is traversed by
the suspensory ligament of the lens, the zonule of Zinn. The processes are
lined internally by a layer of non-pigment cells, and to the outer
side of these is placed a layer of pigmented cells. These two layers
represent the continuation forwards of the retina beyond the ora serrata,
and are called the "pars ciliaris retinae." The remaining portion of the
ciliary processes consists of a connective tissue stroma, containing branched
pigment cells, and an extraordinary number of blood vessels. The processes
are supposed to secrete the fluid which nourishes the eye, and an inflamma-
tion of them (cyclitis) is always of serious moment. The outer part of the
ciliary body is formed chiefly by the ciliary muscle, the latter being arranged
in two layers. One of these runs meridionally, arising about the sclero
corneal margin, and goes backwards to be inserted into the anterior portion
of the choroid, whilst the other layer, situated more internally, runs circu-
larly around the ciliary processes.
The Aqueous Kumar is a limpid fluid, which normally contains a small
amount of albumen. It fills the anterior and posterior chambers, and is
chiefly secreted by the ciliary processes, and reaches first the posterior
chamber, from which it passes through the pupil into the anterior chamber,
making its exit from the eye by way of the ligamentum pectinatum and
Schlemm's canal. The fluid is constantly and slowly secreted according to
requirements, but when the aqueous escapes, as in perforating wounds of
the cornea, it is produced again very rapidly, the anterior chamber being
re-formed in a few minutes. The aqueous humor serves as a medium in
which the iris can freely act, and it also supplies the nourishment to the
lens and cornea.
Three' systems of blood vessels exist in the eye: the conjunctiTal,
retinal, and ciliary. The arteries of the ciliary system are as follows:
(1) The posterior ciliary arterites enter the interior of the eye
through the sclera posteriorly, most of them passing at once into the
choroid. Two of them, however^ one on either side, run between the
choroid and sclera as far forwards as the ciliary muscle, Avhere each divides
into two branches that proceed in a direction concentric Avith the margin
THE IRIS AND CILIARY BODY.
75
of the cornea, encircling the latter, and giving off the arteries to the iris.
These latter run in a radial manner from the ciliary to the pupillary
margin, and shortly before they reach this they form, by anastomosis, a
second and small vascular circle.
^k- 43-
Diagram of circulation in the eye. The arteries arc shaded, and the veins black.
A Cornea. B Canal ot Schlemm. C Circuius arteriosus major. D Conjunctional
vessels. E Recurrent artery of choroid. F Anterior ciliary vessels. G Sclera.
//Choroid. / Retina. K Suprascleral vessels. L Vena vorticosa. M Long pt^sterior
ciliarv artery. ^V Short posterior ciliary artery. O it P Outer and inner vessels of
the sheath. R Optic nerve. 6" Central artery and vein of retina. T Vessels of iris.
V Vessels of ciliary process. W Capillaries of choroid.
76 THE IRIS AND CILIARY BODY.
(2) The anterior ciliary arteries. These, coming from the front, and
arising from the arteries of the four recti muscles, perforate the sclera near
the corneal margin, and anastomose with the circle formed by the two long
posterior ciliary arteries.
The arrangement of the veins, which take the blotxi back to the heart,
is quite different from that of the arteries. Most of the blood from the
ciliary body and iris passes out of the eye by four large vessels, called vensp
vorticosse, which perforate the sclera in a very oblique direction, slightly
behind the equator of the eyeball. Some of the blood from the iris and the
ciliary muscle escapes by veins which pass directly out of the sclera, and
which come into view beneath the conjunctiva near the margin of the
cornea. These are called the anterior ciliary veins, and they correspond to
the anterior ciliary arteries. They principally constitute the violet vessels
which we see running backward beneath the conjunctiva in glaucoma and in
ciliary injection.
THE PUPIL.
The iris performs two functions. Firstly, it controls the amount of
light entering the eye (the less the illumination, the larger the pupil, and
the greater the illumination, the smaller the pupil), thus preventing an
intense light from injuring the retina. Secondly, it cuts off the marginal
rays, which would, unless arrested, diminish the sharpness of the retinal
image, owing to the difference in refraction of the periphery of the cornea
and lens from that of the centre.
Contraction is produced by the sphincter pupilla^ muscle a layer of
unstriped muscular fibres arranged concentrically around the pupil. The
blood vessels of the iris, when distended, by broadening the ins, also
diminish the pupillary aperture. The pupil is supplied by the third nerve
as also is the ciliary muscle (the muscle of accommodation).
Dilatation is probably partly a muscular act and partly due to the
inherent elasticity of the iris, owing to the presence of numerous elastic
fibres in its posterior layers. Some authorities doubt the presence V)f a
dilating muscle, Avhilst others assume that the dilatation of the pupil is
wholly due to muscular effort. The muscle fibres are arranged in a radial
manner, but are very thin, and the sympathetic nerve supplies them. Con-
traction of the blood vessels of the iris, as by cocaine, narrows it, and so
increases the size of the pupil. Like all other sphincters in the body, that
of the iris maintains a tonic contraction when at rest, as is exemplified by
the contraction of the pupils during sleep.
The normal size of the pupil varies very much within the limits of health
in different individuals, delicate and nervous children and myopes having
generally very large pupils, whilst in elderly people and hypermetropes the
aperture is generally small, as also in many cases of early spinal disease.
Normally both pupils are of equal size, and any difference is due to some
pathological condition.
THE IRIS AND CILIARY BODY. 77
The reaction of the pupil takes place involuntarily and unconsciously.
It is either reflex, in which case the stimulus is transmitted from the brain
to the nerves of the iris, as in an increase of illumination ; or it is associated,
as in the act of accommodation, when the pupillary fibres of the third nerve
are set into action simultaneously with those supplying the ciliary muscle.
Uoficj- Mot'cmcuis. The pupillary reflexes are three in number:
(1) Light reflex ; (2) reflex on associated movements of the eyes : (3) reflex
to sensory stimuli.
(1) Light reflex. There are two distinct reflexes (a) the direct,
(b) the indirect or consensual light reflex.
(a) The direct light reflex consists in the alterations that take place in
the size of the pupil, when, one eye being screened, the other is exposed to
varying degrees of light. An increase of light causes an immediate con-
traction, and a diminution of light a dilatation. We see this if we close
one eye of the patient, and then alternately shade and expose the other eye
to daylight by moving the hand in front of the eye, or fecal illumination
may be used, especially in elderly people, where the reaction is not so
sensitive. The response of the pupil, both as regards the range of move-
ment and its rapidity, should be noted.
(h) The indirect or consensual reflex of the pupil is the alteration that
takes place in the pupil of the covered eye whilst the other is being tested
for its response to direct light stimulation. In health the consensual reflex
is equal to and synchronous with the direct reflex.
When an eye is completely blind the direct light reflex is lost, and the
pupil is moderately dilated, assuming the position that a normal eye would
have in the dark. At the same time, provided that there is no paralysis
of the third nerve, or interference with the ciliary muscle, the pupil will
react to consensual light. (Fig. 44.)
The light reflexes may be absent, though the eye has perception of light.
This may be due to interference in the transmission of the impulse from
the brain to the ciliary muscle, as in paralysis of the third nerve, or to the
action of mydriatics, as atropine, etc., or it may be due to injury of the
muscle, sometimes caused by a direct blow on the eye, or the pupil may be
bound down, as the result of previous inflammatory attacks.
(2) The reflex in associated movcuK nfs. This always consists in a con-
traction of the pupil, and occurs -
(o) In convergence (acting with the internal recti) ;
(6) In accommodation (acting with the ciliary muscle).
The convergence reflex is best observed by directing the patient to look
first into distance, then at one of the fingers held within a few inches of the
eye. The contraction should be equal and synchronous, but is not so well
marked as that due to light. It is dependent more upon convergence than
accommodation, as it is well seen in high degrees of myopia, in which the
accommodation is not employed. In a disease of tlie spine, due to syphilis,
called locomotor ataxia, the pupils do not react to light, but do so to
accommodation.
78 THE IRIS AND CILIARY BODY.
(3) Beflex to sensory stimuli. Tickling of the skin in various parts oi
the body, and strong psychic stimuli, a fright, etc., produce dilatation of
the pupil.
The application of certain drugs, as atropine, homatropine, cocaine,
etc., dilate the pupil, these being known as mydriatics.
Mydriatics. Atropine paralyses the sphincter and ciliary muscles, and
kence dilatation of the pupil results, and also inability to see clearly close
to. Its effects last for about a week. In practice 1 per cent, of atropine
sulphate is most frequently employed, either in water or in the form of an
ointment, or atropine may be dispensed in an oily form. The drug should
be used with discretion, and only with young people, except in diseased
conditions of the eye, as iritis, etc. Some children are very susceptible to
atropine, this causing a reddened condition of lids and face, which, how-
ever, quickly subsides on discontinuance of the drug. It rarely causes
symptoms of general poisoning, but they sometimes occur, and manifest
themselves in dryness of throat, and sometimes delirium. The oily and
ointment forms are the best, and least likely to cause any objectionable
symptoms in children.
Duboisin,, hyoscyamine and hyoscine are chiefly used as "^substitutes for
atropine when that drug causes toxic symptoms.
Homatropine is a very useful mydriatic, as it dilates the pupil more
quickly than atropine, and its effects wear off in from 24 to 48 hours. It
is given in 1 per cent, solution, either in water or oil, and is often combined
with cocaine hydrochloride (2 per cent.), as the addition of the latter
results in a greater dilatation of the pupil.
Cocaine hydrochloride (2 per cent, in water) is a valuable mydriatic,
for it does not abolish accommodation, as the above two do, and is particu-
larly useful Avhen a better view of the fundus is desired.
To prevent the possibility of toxic effects resulting from the use of the
above drugs, the lower punctum should be draAvn away from the eyeball,
as the adverse symptoms arise from the fluid finding its way into the
stomach via the nasal duct. The patient is directed to look up, and the
lower lid is drawn outwards, the fluid being inserted between the eyeball
and the lid. It may also be instilled by asking the patient to look down,
and raising the upper lid, a drop of the lotion being placed on the sclera
above the cornea. It is also advisable to order smoked glasses when
giving atropine.
Myotics. These are drugs which contract the pupil. That most com-
monly used is sulphate of eserine, and it is generally applied as a 1 per
cent, solution. It not only contracts the sphincter iridis, but also the ciliary
muscle. Its instillation is followed by pain and headache, and a feeling
f great tension in the eye.
THE IRIS AND CILIARY BODY. 79
Other myotics used ai* the extract of Calabar bean and nitrate of pilo-
carpine.
Clinical Examination of Iris and Pupil. Focal illumination is neces-
sary, and the pupillary reaction, both to light and accommodation, must
always be note<l, as their absence is pathological. Also the position of pupil
should be noted, as to whether centric or eccentric, and whether round or
irregular in shape. The pattern of the iris should be observed, any blood vessels
or lymph present being always an indication of past disease.
Abnormal coNrixioN of the Pupils. They may be either abnormally
dilated (mydriasis), or contracted (myosis), and one or both of them may
be affected.
Mydriasis. The causes may be within the eye (intraocular) or outside
the eye (extraocular).
The following intraocular conditions may produce mydriasis :
1. Increased or glaucomatous tension of the globe, by paralysing the
ciliary nerves.
2. Laceration of the sphincter muscle of the iris by contusions or
wounds.
3. Injuries involving the ciliary nerves, as by a dislocated lens.
4. Diseases of the choroid and retina, by lessening the sensibility to
light.
The extraocular changes causing mydriasis are:
1. Paralysis of the third nerve.
2. Disease of the optic nerve or tract, causing a diminished sensi-
bility to light.
3. Irritation of the sympathetic nerve, generally caused by enlarged
glands in the neck,
4. Nervous shock.
If the visual acuity can be improved by the pinhole disc, the cause of
the dilatation is probably due to interference with the centrifugal fibres.
(Fig. 44.)
THE OPTIC TRACTS AND PUPILLARY ACTIONS.
The field of vision common to the two eyes is composed of a right half G
and a left half G^ The former corresponds to the left halves of both
retinee L and L, the latter to the right halves R and R. The boundary
between the two halves of the retina passes through the fovea centralis, at
8o
THE IRIS AND CILIARY BODY.
which the visual line (V) drawn from the point of fixation F impinges on
the retina. The optic nerve fibres from the right halves of the retina all
pass into the right optic tract, and the fibres from the left halves into the
left optic tract. This follows from the inner fibres of both optic nerves
crossing over and passing to the other side, at the place called the optic
chiasma. The optic nerve O extends from the eyeball to the chiasma ;
after that it is called the optic tract T T. Each optic tract contains
fibres from both retinae, and is continued up to the back or occipital
part of the brain B, where the centre for vision is situated. Prior to
reaching there it gives off fibres M^ which go to the nucleus of the third
nerve KK^^in which are placed the centres for convergence, accommodation
and pupillary reaction.
Fig. 44.
Schematic representation of optic tracts and pupillary actions. {After Fiichs.
Presuming there is a lesion in the optic tract at G G, preventing retinal
impulses from reaching the brain, there would be no visual perception in tlie
right half of the field, owing to the left halves of both retinae being cut off
from the brain, and this condition is called right hemiopia. but both pupils
would react, owing to the right halves of the retinae being sensitive. A
lesion at X would cause total blindness of left eye, and loss of direct pupil-
lary reflex, but the consensual reflex would be present, the impulse
THE IRIS AND CILIARY BODY. 8i
travelling to the left optic tract from the left part of the right retina,
and so on to the third nerve nucleus of the loft side. Any interference
with the third nerve, say at O c, would result in abolition of pupillary and
accommodative actions, but vision would be more or less undisturbed.
A lesion at E E, above where the pupillary fibres are given off, would
cause hemiopia, but pupillary reactions would be normal. A lesion at 8 S
would destroy the function of the nasal parts of both retinse, and so produce
temporal hemiopiji.
CONGENITAL ABNORMALITIES OF THE IRIS.
Colohoina of the Iris is a congenital deficiency of a portion of the iris,
caused by non-closure of the anterior portion of the foetal cleft, so that
defect chiefly occurs in the lower median line (Fig. 45), and is often asso-
ciated with a similar defect in the choroid or optic nerve sheath. There is
often a family predisposition to this defect.
^(^' 45-
Coloboma of the iris,
Xnindia. ^This is congenital absence of the iris, which may be entirely
absent, or represented merely by a rudimentary stump attached to the
ciliary processes. There is no interference with the secretion of the
aqueous humor, this showing that the iris does not take a large part in the
secreting process, as was previously held to be the case.
Irido-done.si.<< or Tremulous Iris. These terms are applied to an iris
which trembles or vibrates on movement of the eye, a feature caused by loss
of the support afforded by the lens. The absence of the latter may be either
congenital or acquired, and is discussed more fully in Chapter VIII.
Variations in Colour. The depth of colour of the iris is in proportion
to the density and amount of pigment in the stroma, small localised patches
of increased colour being physiological, and not uncommon.
In albinos (white-haired children), where there is a general lack of pig-
ment, not only in the stroma, but also in the posterior pigmentary layer of
the iris, and in the retina and choroid, the iris appears greyish white and
translucent, allowing the red reflex of the fundus to shine through and
give the eye a pinkish hue. Albinism is generally associated with nystagmus
and a lowered vistinl acuity.
82 THE IRIS AND CILIARY BODY.
It is not unusual to note that one iris is of a different hue to the other,
and in eyes blind from disease, especially in old glaucoma, the iris often
assumes a greenish tinge.
Fig. 4.6.
Diagram showingr remains of pupillary membrane below, and two posterior synechial
above, as seen under a mydriatic. C Remains of pupillary membrane, which arises from
the anterior Surface of the iris. There is no interference with dilatation of pupil at this
point. A & B Old posterior synechiae, the result of a previous iritis. They spring from
the edge of the iris, binding the latter down to the anterior capsule, and owing to their
non-elasticity, preventing it from retracting when a mydriatic is instilled.
Capsular Pupillary Membrane. In foetal life a vascular membrane
stretches across the pupil, Avhich generally entirely disappears about two
months before birth, but occasionally parts of it remain as greyish tags
running from the iris to the capsule of the lens. These greatly resemble
the posterior synechise remaining after iritis, but the latter spring from
the pupillary margin of the iris, whilst the former spring from the anterior
surface of the iris, about the circulus iridis minor. Sometimes the pupillary
membrane persists as a few brown dots on the lens capsule. The pupillary
membrane, owing to its elasticity, does not interfere Avith the dilatation of
that part of the pupil to which it is attached.
Corectopia, or Displacement of the Pupil. This is commonly seen in
association with congenital displacement of the lens, and is due to the same
cause, namely, a maldevelopment of the ciliary processes and suspensory
ligament.
Discoria, or Alteration in the Shape of the Pupils. The pupil may occa-
sionally be oval instead of circular, caused sometimes by the traction of a
tag of capsular pupillary membrane.
Aniscoria, or Inequality of Pupils. ^^This is practically alwaj's a patho-
logical condition, though occasionally is occurs congenitally.
DISEASES OF THE IRIS AND CILIARY BODY.
When it is recalled that the iris, ciliarj' hotly and choroid closely
resemble one another histologically, that their blood supply is identical,
and that they form with each other a continuous membrane, it is rather
surprising that any one of these three divisions of the uveal tract can
become inflamed whilst the other two remain perfectly healthy. Yet this is
THE IRIS AND CILIARY BODY. 83
not unfreqiieiitly the case, although it is more common for the iris and
ciliary body to be simultaneously affected. An inflammation of the iris is
called iritis, and of the ciliary body cyclitis, and when both are involved 't
is called irido cyclitis. It is advisable to describe the symptoms and course
of iritis and cyclitis separately, and later to paint the clinical picture of
the two combined. Clinically we cannot always know whether only one or
more divisions of the uveal tract are involved, but in every severe case of
iritis more or less cyclitis is always present, whilst in slight iritis there is
generally no cyclitis.
Iritis. In iritis the severity of the symptoms bears a direct relationship
to the intensity of the inflammation, and ail degrees of the latter are met
with, from a slight congestion of the iris, in which the blood vessels are
dilated and the pupil contracted, but in which no exudate or lymph appears
on the iris, to a very severe inflammation, resulting in the formation of pus
(hypopyon) in the anterior chamber,
Hypersemia, or congestion of the iris, occurs secondarily to some
corneal or conjunctival affection, especially in the case of a foreign body in
the conjunctival sac, or a corneal ulcer. The symptoms are those of the
exciting affection, the pupil is contracted, and reacts sluggishly to light,
but dilates regularly on the instillation of a mydriatic. The iris is also
slightly discoloured, most noticeable when compared Avith that of the other
eye. Some little ciliary injection around the corneal margin is frequently
present. In this condition the blood vessels of the iris are merely dilated,
owing to some reflex irritant, but no lymph is poured out of the vessels into
the subjacent tissues, and the absence or presence of this lymph or exudate
always distinguishes a hyperaemia from an inflammation, whatever part of
the bo<ly is affected.
Two degrees of iritis are met with clinically acute and chronic.
(1) Acute Iritis. The degree of pain in iritis is very variable (depend-
ing to some extent upon the cause of the iritis). In gonoirhoeal iritis it is
very severe, but in syphilitic it is only slight. The pain is of a neuralgic
character, either in the eye or around the brow, extending over the side of
the head or down the face.
Intolerance to light is not usuallj- a marked feature, though some
photophobia is generally present, yet it is never so marked a feature as
that intense dread of light so characteristic of some corneal affections.
There is always considerable impairment of vision, which increases as the
disease advances, and arises from turbidity of the aqueous, caused by the
lymph, exudcxl from the iris, becoming deposited on the capsule of the lens
in the pupillary area. The power of accommodation is also frequently
impaired, owing to extension of the inflammation to the ciliary body.
Lachrymatiou is a common symptom when much photophobia is
present, but there is no gumming of the lids in the morning, which is such
a prominent sign of conjunctivitis.
84
THE IRIS AND CILIARY BODY.
Clinical Signs. In slight cases there is well-marked ciliary injection,
distinguished as a pink or pale violet zone around the cornea, in wl;ich the
separate vessels cannot be seen, but in the more severe cases much con-
junctival injection will also be present. (Plate II.)
By focal illumination the cornea will, at the first glance, appear hazy,
but this is due to turbidity of the aqueous humor. It is in the iris, of
course, that the changes are most marked, and a discolouration, a loss of
lustre, and an indistinctness of the pattern will at once be recognised.
The loss of lustre and of distinctness of jattern are due to the presence
of lymph, both in the stroma and on the surface of the iris^ and to cloudi-
ness of the aqueous humor. The change in colour, a blue iris becoming
greenish, and a brown one yelloAvish, is due to hypersemia of the iris, as
well as to the presence of inflammatory products.
The pupil is contracted, and more or less inactive to light or accommo-
dation . The impaired mobility and the contracted pupil are due to engorge-
ment of the blood vessels of the iris, to spasm of the sphincter muscle, and
to posterior synechise. Exudation of inflammatory products (lymph) is
present in greater or less degree, and may be found on either surface of the
iris, in the pupil, in the aqueous humor, and in the tissue of the iris. The
lymph or exudate is a thick, gummy fluid, and causes adhesions to
form between the iris and the anterior capsule of the lens, generally only
at the pupillary margin, these adhesions being called jjosterior synechice.
The presence of posterior synechise is ascertained by observing the reaction
of the pupil when intense and weak light are alternately thrown upon the
eye, the pupil dAating only at those places where there are no synechia;.
The instillation of a mydriatic brings out this fact more clearly.
Seclusion and occlusion of the pupil, showing "iris bomb^."
The iris is adherent by its entire puoilljiry mar^jin, but is elsewhere pushed forward.
The posterior ch iniber, H, is thus deeper; th.; ;interior. V, shallower, especially at the
periphery, where the root of the iris. A, is prcssi d against the cornea by the increase
of tension In consequence of irictii.n oi\ ihe iris it^ pigment is separating at S, to
bs left upon th,^ lens capsule. The pupil is cKiSt-d by an exudate membrane, O, by the
shrinkintf ot which the anterior c ipsule is thrown into folds. In the lowei part ot the
anterior cha'uber there is m itter, P, precipiiited iip.ui the posterior surface of the cornea.
In c inssquence of thi increase ot tension, both the cilia-y pr.>cess3s, C, and the ciliary
muscle. M, a-'e atrophic and fl .ttened. The cortex of the lens has undergone cataract-
ous disintegration, and at /? is s -parated fioni thi capsulj by liquor Morgagni, the
nucleus, /T, of the lens being unaltered.
Plate II.
^.CONJUNCTIVITIS.
Note. Redness less at corneal margrin, vessels branch and are tortuous. Cornea is clear.
pupil normal, and pattern of iris well marked.
A-CILIARY INJECTION IN CHRONIC IRITIS.
Note. Redness at corneal marg^in, and pale in tint, the vessels themselves not being
seen. Iris indistinct, pupil contracted
C.-CHRONIC IRITIS.
Note.- Slight redness at corneal margin, absence of conjunc ival injection.. Pattern of
iris ill detined, pupil irregular.
/), -ACUTE IRITIS.
Note. Conjunctival and ciliary redness. Pattern of iris obscured, pupil contracted.
THE IRIS AND CILIARY BODY.
85
Sometimes the entire pupillary margin becomes adherent (seclusio
pupillte), and then the posterior (hamber is completely shut off from the
anterior, so preventing escape of aqueous into it. As a result, glaucoma
(increase of tension) supervenes, and the iris, being attached now at the
pupillary as well as the ciliary margin, becomes bowed forwards between
those attachments by the continuously increasing fluid in the posterior
chamber, and this condition is termed "iris bombe" (Fig. 48). In recurrent
attacks of slight acute iritis, or in chronic iritis, it is important to observe
how much of the pupillary edge of the iris is bound down, and where nearly
the whole of it is involved an iridectomy (removal of part of the iris) must
be undertaken when the eye is quiet, in order to prevent the incidence of
iris bombe and glaucoma, which cause a complete and permanent destruction
of vision in a few hours. The iridectomy allows of the escape of aqueous
from the posterior to the anterior chamber, and its egress from the eye
through the angle of the cornea. If the area of the pupil be filled wit'^
exudation, the condition is known as occlusio pupillse, which is generally
associatetl with seclusio pupillse. In the more severe cases of iritis the
exudate more or less fills the anterior chamber, looking like matter or pus,
and this condition is called hypopyon.
Opacities in the choroid are frequently present, owing to the involve-
ment of the ciliary body, and keratitis punctata (see cyclitis) will be
observed on the back of the cornea.
Beginners are very liable to confuse iritis with conjunctivitis, and
below are tabled the chief points of difference (Plate II.) :
Coujtin rtivif/s.
Pain, as if a foreign body were in the eye.
Lids gummed together in the morning:, and
mucopurulent discharge is present in the
conjunctival sac.
Conjunctival injection present.
Cornell clear.
Iris normal, and pattern well marked.
Pupils active and normal.
Tension normal.
Iritis.
Pain Of a neuralgic character, commonly
referred to hrow.
No gumming of lids, no discharge present in
sac.
Ciliary injection is chiefly present. In severe
cases, also conjunctival injection.
Cornea .nppears hazy, owing to turbidity of
aqueous humor.
Iris discolored, pattern indistinct.
Pupils contracted and only slightly active,
posterior synechiae present.
Tension normal.
Cause of Iritis. It may be a primary disease, or it may be secondary to
an inflammation of one or other of the coats of the eye, as a corneal ulcer
(secondary iritis). . .
Primary Iritis is a blood infection, by which is meant that the poison
causing the iritis is carried to the iris by the blood.
86 THE IRIS AND CILIARY BODY.
Rheumatism and gout very rarely, if ever, cause iritis, though until
recently they were mentioned as frequent factors in the cause of this disease.
The source of the poison lies generally in the collection of pus (matter) in
some part of the body, especially under the gums, around the teeth (calletl
Riggs' disease), or in the nasal sinuses (mast commonly the sphenoidal), in
which the patient oft^n states he has a chronic catarrh, a condition which
practically does not exist. The pus may also be in an abscess of the ear,
and in women breast abscesses and infection of the genital organs are
fruitful sources of the poison. Probably auto-intoxication from the intes-
tine occasionally causes the condition.
Gonorrhoea is a common cause, and the attack is frequently very painful
and severe. Syphilis commonly causes it, and it is then characterised by a
peculiar tendency to the formation of nodules perhaps as large as millet
seeds along the margin of the iris. Pain is only slight in syphilitic cases.
General infections, such as pneumonia, typhoid and influenza, occasionally
give rise to iritis.
Prognosis. The length of duration of an attack cannot be foretold at
the outset, as it depends largely upon Avhether we are able to determine and
eradicate the source of the poison. If not, recurrences are the rule, but
fortunately, in the large majority of cases, such determination is possible,
but it involves examination of other cavities of tlie body, especially that of
the nose. The presence of synechise was formerly thought to increase the
tendency to recurrence, and various operations were devised and practised
for the excision of these adhesions, but they have been completely aban-
doned, as the presence or absence of synechise does not influence the ten-
dency to other attacks.
Treatment. For the attack, hot fomentations of boric acid, and, in the
severe cases, leeches are applied to the temple and behind the ears, and
atropine is instilled frequently into the eye until the pupil is dilated. To
prevent further attacks, the source of tlie poison must be eliminated. Dark
protective glasses should be worn during the attack, and in A-ery severe cases
the patient may have to be confined to a dark room or to bed.
Chronic Iritis. The symptoms are similar to those of acute, but less
intense ; generally only slight pain, chiefly of a neuralgic character, and
intolerance to light, are complained of. The visual acuity may be more or
less normal. This condition can only be diagnosed on examination of the
iris and pupil. Slight ciliary injection is generally present.
The pupil will be slightly contracted and irregular, and will react
unequally to light, the part not bound down to the iris only reacting to the
varied illumination. The iris may be slightly discoloured, the pattern
obscured, and blood vessels may be seen running over the surface always
a pathological phenomenon. At some part of the edge of the pupil exudate
will be observed as a small Avhitish spot, or in the pupillary area brown spots
of pigment may be seen, these representing spots where former synechiae
e-xisted, and which had been ruptured, leaving a little of the pigment from
the posterior layer of the iris upon the capsule.
THE IRIS AND CILIARY BODY. 87
In the formation of posterior synechiae, it is not the stroma of the iris,
but the layer of retinal pigment covering its posterior surface, which
becomes adherent to the capsule of the lens, and when rupture of a synechia
occurs, the line of severance is that between the posterior retinal pigment
layer and the rest of the iris, owing to the loose attachment of the former
to the latter, and not between the posterior retinal pigment layer and the
exudate. On instillation of a mydriatic the irregularity of the pupil and
the synechise will be brought into greater prominence.
Inflammation of the Ciliary Body Cyclitis. In acute cases this is
always complicated with iritis, and the clinical picture described for that
applies to this condition.
Chronic Cyclitis, often associated with chronic iritis, is an insidious and
more or less painless disease, and the ciliary body, as the result of the
inflammation, produces. an increased secretion into the posterior chamber.
This secretion is more viscid than the ordinary aqueous humor, owing to its
containing a greater amount of albumen.
Symptoms. The earliest symptoms are slight ciliary redness, generally
more marked at one spot, accompanied by lachrymation, and sometimes a
feeling as if the eyes were too full. In the early stages, and even later,
there is little interference with visual acuity.
Clinital Signs. The slight ciliary redness at once points to a patho-
logical condition, and on examination by focal illumination the cornea wilJ
appear transparent and normal, but the anterior chamber is deeper than
usual, owing to hypersecretion of the aqueous. The characteristically dis-
tinctive sign of cyclitis is the deposition of punctate fibrinous particles
upon the back of the cornea (Descemet's membrane), called keratitis
punctata, but more commonly spoken of as K.P. (Fig. 32). These particles
are generally round in form, of a brownish hue, and arranged in the form
of a triangle, with the base downwards, this peculiar shape being doubtless
due to gravity, for at first, on leaving the ciliary body, they are suspende<l
in the aqueous, but by virtue of centrifugal force caused by the rotation
of the eyes and head, they are thrown against and adhere to the posterior
surface of the cornea, and in so doing they arrange themselves according
to weight, the largest and heaviest being lowest down.
The K.P. are particles containing pigment cells derived from the ciliary
body, but sometimes they are only fibrinous in nature (like exudate), and
then they appear greyish or white instead of brown. These deposits are
easily overlooked, because they are so minute, and can only be seen by
focal illumination and a strong magnifying glass, such as a corneal loupe, or
by a -f 20 D or -f 30 D behind the ophthalmoscopic mirror. Their shape,
colour and arrangement are so peculiar as to render confusion with any
other condition, in a typical case, impossible. Occasionally they may appear
singly, or scattered irregularly over the back of the cornea, or they appear
as large white spots, looking, to the naked eye, like a deposit of mutton fat.
"When complicated with iritis, the usual changes in the iris will also be
88 THE IRIS AND CILIARY RODY.
not-ed. In the later stages of cyclitis slight vitreous opacities (like dust;
will be detected in the vitreous, but only by the use of the plane mirror ami
a low illumination.
Cyclitis often occurs in middle-aged women, and occasionally in men,
and the causal factor is, as in iritis, the absorption of toxic products caused
by microbes. The recognition of this disease in its early stage is important,
and, where slight ciliary congestion is present, even when visual acuity is
normal, the pupil, iris and back of cornea should always be carefully
examined, in order to exclude chronic cyclitis or irido cyclitis. This disease
is probably the one most frequently overlooked by opticians, who really
ought to have no difficulty in recognising it.
Treatment. This is directed to the removal of the cause, and the
application of hot fomentations to the eye. When increase of tension takes
place it is occasionally advisable to allow some of the aqueous to escape
from the anterior chamber by an incision in the periphery of the cornea.
This is called a paracentesis of the anterior chamber,
Irido-cyclitis. This presents the symptoms and clinical characteristics
of both iritis and cyclitis, and the diagnosis of it is made in the same
manner. Clinically K.P. is noted, together with discolouration and indis-
tinctness of pattern of the iris, and contraction and slight activity of the
pupils.
INJURIES OF IRIS AND CILIARY BODY.
Foreign Bodies.- -These, when of small size, such as bits of steel or iron,
may perforate the cornea and become imbedded in the iris or lens (if in the
latter it becomes gradually opaque). The puncture in the cornea rapidly
closes, and perhaps hardly any aqueous humor is lost. It is generally
advisable to remove the foreign body without delay, using the large electro
magnet when the foreign body is of a metallic nature.
Hyphcema, or TlrrAnorrhage into the Anterior Chamber, is the most
common form of intra-ocular haemorrhage, and the least serious to the eye.
In amount it may vary from a few drops of blood to a complete filling of
the anterior chamber. The hsemorrhage is usually caused by rupture of one
of the superficial vessels of the iris, or by a separation of a portion of the
iris from the ciliary body (coredialysis). The blood sinks to the bottom of
the anterior chamber, quickly coagulates, and is recognised as a reddish
mass situated in the lower part of the chamber. The blood is fairly rapidly
absorbed, and where there is no external wound of the eye no serious conse-
quences result. Treatment consists in cold applications to the eye, and if
any sign of iritis supervenes the use of atropine is indicated.
Iridodialysis or Coredialysis. This is a separation of the iris from its
ciliary border, by which a neAv pupil is frequently formed. It is generally
cause<l by a smart bloAv on the eye, such as the cork from a bottle of soda
THE IRIS AND CILIARY BODY. 89
water, or an accidental blow from an elbow. The separation of the iris from
its ciliary connection is followed by free haemorrhage into the anterior
chamber, often completely occluding it. When the hsemprrhage is absorbed
/"ig. 4.8.
Iridodialysis.
The pupillary margin opposite the detached area is straight, and ihe rounded shape of the
pupil is lost. In the interval between the edge of the torn iris and the cornea may be seen
the niargin of the lens, L. P Represents the apices of the ciliary processes, the fine
radiating lines between the two representing the zonule of Zinn. K Is the circulus iridis
I' " minor, and C the contraction furrows of the iris.
there is found at the ciliary margin of the iris a black crescent, correspond-
ing to the area of separation of the iris from the ciliary body. The
separateti edge of the iris is straight, and its pupillary border does not
react to light, owing to rupture of the ciliary nerve, hence the pupil is not
circular in shape. The sight is but little affected by iridodialysis, but
monocular diplopia occurs, unless the object be accurately focussed.
Laceration or Bupture of the Sphincter /ritZis.- -This occurs also as the
result of severe blows. The pupil remains fairly dilated and more or less
immobile, and there may be recognised after a careful examination one or two
torn parts along the pupillary border. Slight rupture of the sphincter is the
commonest cause of a monocular dilated pupil. Occasionallj* the ciliary
muscle is also paralysed or weakened, states recognised by a diminution of
the amplitude of accommodation.
Fig. 49.
Radial laceration of the iris. Situated below are slight lacerations involving the
pupillary border, as evidenced by the notches in the dilated pupil.
Prolapse of the Iris. A condition caused by a penetrating wound of the
cornea, especially if situated near the corneal margin. It is generally
advisable to remove the prolapsed part of the iris.
go THE IRIS AND CILIARY BODY.
Wounds involving the ciliary region are especially dangerous, owing to
tht> great liability of sympathetic inflammation occurring in the other eye.
This is most commonly manifested as a chronic cyclitis, whose symptoms
and diagnosis have been detailed above. Tumors and cysts of the eye are
rare, but easily recognised. The treatment is operative.
DISORDERS OF MOTILITY OF THE IRIS.
The above manifest themselves in a diminished pupillary reaction^ and
in an alteration in the diameter of one pupil. "When afi^ecting one eye, such
is easily noticeable, and any inequality in the size of the two pupils is
always pathological. The pupil may be dilated (mydriasis) or contracted
(myosis).
Mydriasis, affecting one eye, is nearly always due to interference with
the third nerve or its centre. It may be caused by syphilis or diphtheria,
by the instillation of a mydriatic, or by direct injury of the iris or ciliary
muscle.
Myosis is often associated with spinal lesions and the instillation of
myotics.
OPERATIONS UPON THE IRIS.
The removal of a porton of the iris is called an iridectomy, which may
be performed for optical reasons, as when a central opacity of the cornea or
lens exists. The new pupillary aperture is called a coioboma, and is narrow
and small when made for securing improvement in vision. An iridectomy
is also performed in glaucoma, in order to secure a freer exit for the
aqueous. In those cases the coioboma is wide, and extends to the periphery
of the iris. An iridectomy is also usually performed just previous to
extracting the lens in the cataract operation.
^
ABC
^4'-- so.
Showing three types of coioboma.
(rt) In glaucoma, it is wide and extends to the periphery.
(i) For optical reasons it is narrow and does not extend to the edge of the iri>*.
(c) In cataract extraction, it is fairly narrow, and extends to the periphery,
THE CRYSTALLINE LENS.
Chapter VIII.
ANATOMY.
The crystalline lens is a transparent and colourless structure of
lenticular shape and of a soft consistence, enclosed in a tight elastic mem-
brane called the capsule. Its circumference is circular, is called the
equator, and represents the line of junction of the anterior and posterior
halves or surfaces. The posterior surface is more liighly curved than the
anterior, and the summit of curvature of each surface is respectively known
as the anterior and posterior pole. The sagittal diameter (thickness of the
lens) measures in the adult five millimetres, and the equatorial diameter
nine millimetres.
The lens is imbedded in a shallow cup-shaped depression in the vitreous,
known as the fossa patellaris ; the hyaloid membrane separating the posterior
capsule from the vitreous. The lens lies within the circle forme<.l by the
ciliary processes, but in such a way that its equator is distant about one-
half millimetre from the apices of the processes, and this interspace is called
the circumlental space. Anteriorly the lens is in contact over the pupillary
area with the edge of the iris, but peripherally the latter structure is
separated from the lens by a shallow space the posterior chamber. The
lens is held in position by the suspensory ligament called the zonule of Zinn,
which consists of a series of delicate structureless fibres running from the
ciliary processes to the equator, separating before reaching the latter,
to form a small triangular lymph space known as the canal of Petit. The
capsule of the lens is a homogeneous membrane, thicker upon its anterior
than upon its posterior surface. Though clinically we speak of the anterior
and posterior capsules, yet they are only differently situated parts of Ihe
same membrane. The anterior capsule is distinguished by having a single
layer of cubical epithelial cells, from which the lens fibres originate.
The lens substance is composed of hexagonal fibres, united to each
other by a soft, transpaient substance. They begin and end upon the anterior
and posterior surfaces of the lens, and are grouped in segments arranged
in concentric layers, with their apices towards the poles, and can sometimes
be recognised clinically as a stellate-shaped figure, radiating from the centre
to the periphery, but this is most typically seen in the early stages of
some senile cataracts.
92 THE CRYSTALLINE LENS.
The lens grows continuously throughout life by the uninterrupted
production and elongation o*^ the cubical cells which line the anterior
capsule, and it increases more transversely than antero-posteriorly. It,
after removing the capsule, the lens of an elderly man be crushed between
the fingers, the softer peripheral masses separate, whilst the hardei- central
portions remain uncrushed. The former is called the cortex and
the latter the nucleus of the lens. They are not only different in
consistence, but also in colour, the cortex being colourless, whilst the nucleus
has a yellowish or brownish hue. The continuous production of lenticular
Lens hardened in formalin and dissected to show its concentric laminae (enlarged).
fibres causes compression of those most centrally situated, and, as a result,
they become hardened, or sclerosed, and form the nucleus. Even in early
life the lens has a hard core composed of the sclerosed fibres, and this
gradually increases, so that in old people the nucleus occupies the greater
portion of the lens. There are many individual differences in this respect,
persons of the same age having different sized nuclei, this being of some
practical importance m the operation for cataract.
The sclerosed portion of the lens is hard and rigid, and incapable of
changing its form, so that the more advanced the sclerosis, the less able is
the lens to make that alternating change in shape so essential to the act of
accommodation. Another feature of the youthful lens is that it hardly
reflects any light, but in later years, when the nucleus is dense and large, it
gives by focal illumination a greyish or yellowish reflex, which is often
mistaken for cataract, but by transmitted light no opacity is discernible.
The lens is avascular, and nourishment is probably supplied by the ciliary
body and the anterior portion of the choroid, such nourishment entering at
the equator, and later emptying itself into the anterior and posterior
chambers.
DEVELOPMENT OF THE LENS.
In its early stage the lens consists of a solid rounded mass of cells
derived from the epiblast. This later is transformed into a, hollow vesicle
lined by a single layer of epithelial cells, and enclosed in a thin elastic
THE CRYSTALLINE LENS. 93
membrane (lens capsule). It is surrounded by a vascular capsule (pupil-
lary membrane), supplied by the anterior ciliary vessels and the hyaloid
artery, the latter arising from the central artery of the disc, and running
forward through the vitreous to the lens capsule. Normally this dis-
appears about the seventh month, but it may persist in its entirety
throughout life, and ofFfer no serious obstacle to vision, or the greater part
may disappear, leaving a stalk attached either to the disc or posterior
capsule, and easily recognisable ophthalmoscopically.
The lens fibres are formed by the cells lining the posterior surface of
the capsule growing forward to fill up the cavity, thus forming a solid
body. Hence, when the lens is fully developed (at birth) the posterior
capsule has no lining cells, since they have formed the lens fibres. Gradual
development of the lens goes on throughout life by the proliferation of the
cells lining the anterior capsule, but the lens does not increase in bulk to
any extent, as the fibres become more closely packed, and lose some of
their fluid, this constituting what is known as sclerosis. The older fibres
the central ones are the first to sclerose, so accounting for the fact that
the nuclear part of the lens is less translucent, and in old people reflects
more light.
CONGENITAL ANOMALIES OF THE LENS.
Absence of the Lens congenital Aphakia. This is so rare as to leave a
doubt whether it ever exists.
Colohoma of Lens. A defect seen as a notch in the inferior border of
the lens, and supposed to be due to arrested development of the zonule of
Zinn. It is often associated with colohoma of the iris and choroid.
Congenital displacement of lens.
Congenital Displacement of Lens, or Ectopia lentis. The lens is
invariably displaced upwards, inclining either inwards or outwards. This is
supposed to be due to congenital absence of the inferior zonular fibres
allowing the superior fibres to draw the lens upwards. (Fig. 52.)
Lenticonus. This is a very rare, usually congenital, anomaly of the
lens, which presents a conical prominence upon its anterior or posterior
surface, appearing as if a drop of oil were situated there.
94 THE CRYSTALLINE LENS.
OPACITIES OF LENS CATARACT.
Any opacity of the lens is called a cataract, and we distinguish between
those situated in the capsule (capsular cataract) and those in the lens
substance (lenticular cataract). The causes of cataract are various, ana
are enumerated below :
(1) Congenital cataract. Present at birth, and due to mal-developnient.
(2) Infantile cataract. Arising in early life as a lamellar cataract.
(3) Senile cataract. Arising in old age, owing to interference with the
nutrition of the lens.
(4) Traumatic cataract. Any foreign body coming in contact with the
lens renders that part liable to become opaque, but if the capsule be rup-
tured the whole lens generally becomes swollen and opaque, and if no nucleus
be present (in children), the opaque fibres become more or less absorbed by
the aqueous humor.
(5) Cataract due to constitutional diseases such as diabetes or
albuminuria.
(6) Cataract secondary to some inflammatory or degenerative changes
in the ciliary body or anterior part of the choroid.
Cataracts are clinically classified according to the situation of the
opacity :^
(1) Capsular cataracts, in which the opacity is on or just beneath the
capsule.
(2) Cortical caratact, in which all the cortex is indifferently involved.
(3) Perinuclear cataract, Avhere the opacity is arovind the nucleus.
The symptoms of lenticular opacities consist in a disturbance of vision,
the degree of which depends on the situation and extent of the opacity.
Small, circumscribed, dense, opaque opacities, provided they do not occlude
the pupillary opening, as, for example, anterior polar cataract, cause little
or no interference with sight ; but larger opacities considerably disturb
vision,' and often alarm the patient by the production of peculiar phenomena,
as musc3e volitantes and polyopia. The appearance of muscse volitantes
consists in the patient noticing black spots in the field of vision, which, if
caused by opacities of the lens, change their position only with movements
of the eye, and hence always occupy the same spot in the field of vision (in
contradistinction to vitreous opacities, which alter their place irrespective of
movement of the eye).
Polyopia monocularis consists in the patient seeing the same object
double or multiple with one eye, and it arises from the many images thrown
on to the retina by the optically irregular lens. Muscae volitantes and
polyopia only occur in the earlier stages of cataract. If the lenticular
opacity be situated centrally, vision may be improved when the pupil is
dilated, as in the twilight, whilst if placed peripherally vision will be better
when the pupil is contracted, as in sunshine or under eserine.
THE CRYSTALLINE LENS. 95
Clinical Recognition. No reliance can be placed upon focal illumination
in the early stage of cataract, as all lenses in old people, owing to the large
nucleus, reflect such a lot of light as to appear grey or opaque by oblique
illumination, but in the latter cases, on transmitting light, no shadow is
seen in the red reflex. In advanced cataracts, on the other hand, focal
illumination shows white or dense grey striae or spots.
By transmitted light the diagnosis and position of cataract are con-
firmed. A plane mirror and low illumination are preferable, and the
opacities appear in the early cases as black dots or striae, which stand out in
contrast with the red hue of the pupil. In the advanced stages no red reflex
is seen at all, but in these cases recognition is easy by the naked eye, even
without focal illumination.
The position of the opacity is determined by transmitted light. The
further behind the pupil the opacity lies, the greater and quicker is the
movement of the shadow on turning the eyeball, the movement of the
shadow being in the opposite direction to that of the eye.
Clinical Forms of Cataract. Every opacity begins at some special spot
in the lens, and it may remain permanently limited to this area (partial
stationary cataract), or it may gradually spread over the whole lens, and
lead to total cataract.
^r?- 53-
Anterior polar cataract. A By focal illiiniination. B Sectional view of lens.
(1) Capsular Cataracts. These consist of opacities situated, not in
the lens, but in its capsule. They are stationary, and are sub-divided,
according to their position, into anterior and posterior capsular cataracts.
Their recognition, as also that of partial stationary cataracts, is of some
importance, as the treatment, when vision is not below jg, is purely
optical.
The clinical picture presented by these stationary cataracts is generally
so distinctive as to render their discrimination from the earlier stages of
progressive cataracts quite a simple matter.
(a) AnteHor Capsular Cataract. It appears as a small white dot in the
pupillary area upon the anterior pole of the lens, and may be recognised by
focal illumination as a whole circular opacity, or by transmitted light as a
96 THE CRYSTALLINE LENS.
black dot, wliich, owing to it being practically in the same place as the iris,
remains stationary, or moves very slightly against any movement of the
eyeball. This condition may be congenital or acquired. In the latter case
it is caused by a perforation of the cornea in early childhood, generally the
result of ulceration, and confirmation of the latter will be found in the scar
on the cornea.
Anterior and posterior polar cataract, seen by transmitted light.
(&) Fosterior Polar Cataract. This consists of a small dot, similar to
anterior capsular, but situated on the posterior capsule of the lens. It is
only discovered by transmitted light appearing as a black round dot
moving rapidly in the opposite direction from the movement of the eyeball.
Posterior polar cataract is congenital in origin, and represents the remains
of that part of the hyaloid artery attached to the posterior capsule. This
artery runs in the foetus from the retinal, artery at the optic disc to the
lens, and generally disappears two months before birth. Occasionally that
part of the artery attached to the disc remains, and can be traced ophthal-
moscopically, running forwards into the vitreous.
(2) Partial Stationary Cataracts Involving the Cortex.
(a) Cataracta punctata. They appear as numerous dots of a greenish
hue, scattered irregularly through the cortex, and are of congenital origin.
^k- 55-
Diagrammatic representation of position ot opacities.
A Anterior polar. B Posterior polar. C Lamellar, with its riders D. E Nuclear.
(&) Cataracta fusiformis is a spindle-shaped opacity running from the
anterior to the posterior pole, also of congenital origin. These opacities in
themselves cause only slight disturbance of vision, but the latter is often
defective from other causes.
Plate III.
^.-ANTERIOR POLAR OPACITY, as seen by fix:al illumination.
A-ANTERIOR POLAR OPACITY, as seen by transmitted light.
C LAMELLAR CATARACT, as seen by transmitted light (pupil under atropine).
Note. Opacity denser at margin than at centre. Riders only on upper half, the lower
beinc; the appearance without thorn. Between margin of opacity and edge of
pupil is red reflex corresponding to transparent periphery of lens.
THE CRYSTALLINE LENS. 97
(c) Lamellar or Perinuclear Cataract. This is the most frequent form of
cataract in children, affects both eyes, and originates in early childhood,
when there is a tendency to debility and rickets. The cataract presents a
peculiar and characteristic appearance. With transmitted light it appears
as a central dark disc, surrounded by the transparent, and therefore red
and illumined, periphery part of the pupil. The darkness of the disc is
greater near the edge than in the centre, so distinguishing it from an
ordinary cataract, which is generally densest in the centre at the nucleus.
Along the outline of the opacity, which usually is sharply defined, small
radiating jagged stride, called riders, are occasionally seen, and they project
from the margin of the cataract into the transparent periphery, like the
spokes on the steering wheel of a ship. Plate III.) The density of lamellar
cataract varies very considerably, so that in some cases a modified red
reflex can be obtained throughout the entire opacity when viewed by trans-
mitted light, but the central part is always the more transparent.
The interference with vision is proportionate to the density of the
cataract, and in the slighter forms normal visual acuity may be obtained,
whilst in the denser only g% is possible. Lamellar cataract does not progress
after childhood.
Treatment. When the visual acuity, with the refractive error corrected,
equals ^2> no further treatment is advisable, but if the acuity is less than
the standard, operative means should be resorted to. The latter may
consist in an iridectomy (removal of part of the iris, so making a false
pupil) opposite a clear portion of the lens, or removal of the lens by
needling. This iridectomy is called an optical iridectomy, and only a small
portion of the iris is removed, generally at the inner side. (Fig. 50.) In
the latter operation a needle is introduced through the cornea into the
lens substance, comminuting the latter, and bringing every portion in
contact with the aqueous. The latter may absorb most of the broken
down lens, but it is generally necessary to remove it. It takes from three
to six days for the lens fibres to become opaque and macerated by the
aqueous.
In lamellar cataract an optical iridectomy can only be performed when
the peripheral transparent zone of the lens is fairly broad, but preference is
given to this operation rather tlian destruction of a lens, owing to con-
servatism of accommodation.
Progressive Cataracts. These begin as partial opacities, and gradu-
ally extend until they involve the whole lens. The rapidity of such progress
varies greatly, as there are cases where a transparent lens becomes opaque
in a few hours, whilst in others it takes years.
Senile Cataract. This rarely occurs before fifty years of age. Two
main varieties can be distinguished, sometimes occurring in the same eye
(1) Nuclear Caiaract. The opacity commences centrally, as an ill-defined
haze situated in the perinuclear Jsone.
98 THE CRYSTALLINE LENS.
(2) Striated Cortical Cataract. Here the opacity commences peri-
pherally, and first shows itself as opaque striae or lines in the lens substance,
which radiate from the circumference towards the centre of the lens. This
variety is more frequently encountered than the other, and the opacity may
begin anteriorly or posteriorly. A cataract is said to be immature when
only part of the lens is involved, and mature when the whole is opaque. The
latter is the most favourable time for operation , as the lens separates readily
from the capsule
After a cataract has attained maturity it may slowly degenerate (hyper-
mature cataract), the peripheral part becoming a clear fluid, the hard
nucleus sinking to tlie bottom, and the pupil again becoming clear. In this
case a natural cure has taken place, but such is very rare, and is called a
Morgagnian cataract. Most frequently a hypermature cataract consists of
a milky fluid, which allows of very slight visual acuity, and greatly preju-
dices the good results of an operation.
Senile cataracts have always a firm hard nucleus, and when the latter is
large the cataract appears of a reddish-brown colour so-called black
cataracts.
An ordinary cataract appears pearly grey by focal illumination, and
black by transmitted light.
Of the cause of cataract little is known, but probably interference with
the nutrition of the lens is an important factor, though how such arises is
pure conjecture. The diagnosis of cataract is confined by transmitting
light into the eye, which reveals the opacity as a black body in the red
fundus reflex. The opacity appears to move in the reverse direction to
that made by the patient's head. It is generally sector-shaped, arranged
in a radiating manner, and involving any portion of the lens. If the
whole lens, or that part opposite the pupillary opening, be cataractous, no
fundus reflex will be found.
Symptoms. Both eyes are usually affected, but not simultaneously.
The earliest symptoms are vague, sometimes a general mistiness, varying in
intensity at different times of the day, according to whether the opacity is
central or peripheral. Sometimes the patient complains that the near
glasses are too strong, due to an increased refractive index of the lens. The
diagnosis is made by focal or transmitted light, a merely sclerosed lens
imparting a dull yellowish colour to the pupil by focal illumination, but
seeming to be transparent by transmitted light.
Treatment. Early recognition of progressive cataract is important,
so as to allow examination of the fundus, in order to determine whether an'
operation or not will be advisable later. Medical treatment, either local
or general, does not influence the progress of the cataract. From
time to time various medicines or sera have been zealously but
rashly commended as a preventive or cure for cataract, but they
hardly survive the light of publicity. So long as the cause of
senile cataract be shrouded in mystery, medicinal treatment remains
purely empirical. In the early stages lightly tinted neutral ::^rotectors for
THE CRYSTALLINE LENS. 99
outdoor use are comforting, and when the opacity is chiefly peripheral
stenopaic glasses are sometimes of service. A weak concave glass often
improves distant vision, and may be given for occasional use. Convex
reading glasses generally have to be weakened as the case progresses. Some
patients receive much benefit from amber tinted glasses, which cause in these
cases an extraordinary increase in definitioM, a phenomenon due to pyschic
causes. Blue or smoked glasses may be ordered when the opacity is central,
since these cause a slight dilatation of the pupil.
Surgical treatment is undertaken when the cataract is ripe, or w-hen
immature, if the visual acuity be much diminished. Surgical measures may
be of two kinds :
(1) Removal of the whole lens, including its capsule. The advantage of
this procedure is that no capsule is left to cause further interference with
vision as the result of its becoming opaque, but there is a greater risk of
losing some vitreous during this operation, and in this country preference
is given to the following method.
(2) Removal of the lens by an incision in the capsule, leaving the latter
behind. The disadvantage of this operation is that some lens fibres,
especially in immature cataracts, are liable to be left behind. These later
become opaque, rendering necessary a needling operation. The latter
consists in introducing a needle and making an aperture in the capsule,
quite a simple procedure.
The refractive correction of the aphakic eye after cataract extraction
raises a few points of interest. In the emmetropic eye the static value of
the lens may be regarded as equivalent to a glass lens of -|- 10 D, but after
operations involving incision of tRe cornea there remains 2D to 4 D of
astigmatism against the rule, which must be added to the 10 D sph. This
lens is not ordered until some six weeks or so after the operation^ and
during that time smoked lenses should be worn. The patient at first often
experiences much disappointment at his indifferent visual acuity, even
when he can read | at the test types, and this is a psychical phenomenon
which time gradually remedies. Another curious symptom is occasionally
complained of, and comes on shortly after the operation, viz., the colouring
of all objects red (erythropsia), which disappears in a few weeks.
Traumatic Cataract. This is caused by an injury due to a sharp
instrument or to violence. When the lens capsule is ruptured, allowing
aqueous to permeate the lens, an opacity always develops. The capsule may
be ruptured by sudden violence applied to the eye or the bony parts sur-
rounding it, without any injury being sustained to the external coats of the
eye. The rent in these cases is not in the anterior, but generally in the
posterior capsule, and so the opacity develops posteriorly at first. A blow
on the eye may so disturb the nutrition of the lens as to cause an opacity
even where the capsule has not been torn, and the cataract then appears
as a diffuse opacity. When the traumatism has also caused a tear of the
sclera or cornea, the outlook is much more serious.
lOD THE CRYSTALLINE LENS.
Diabetic Cataract. Its clinical characteristics are similar to senile, but
an examination of the urine reveals the presence of sugar.
Secondare Cataract. When the opacity of the lens is dependent on
and caused by disease of the vitreous, choroid or retina, it is called a
secondary cataract. This opacity often commences at the posterior part of
the lens, and the prognosis is bad, owing to the accompaniment of disease in
the contiguous organs.
CHANGES OF POSITION OR DISLOCATION OF LENS.
The lens is held in position by the suspensory ligament, or zonule of
Zinn, which consists of delicate fibres originating from, the inner surface of
the cilla'ry body, and passing over to become attached to the equator, partly
in front and partly behind it. Changes of position of the lens are due to
changes in the zonule of Zinn, which in the normal eye is tightly stretched,
holding the lens so firmly that the latter remains perfectly immovable, even
with the most violent motions of the head. Any tremor of the lens, or any
displacement from its natural position, is due to a relaxation or destruction
of the fibres of the zonule, and this may affect either a part or the entire
circumference of the zonule. Dislocation of the lens may be complete
(luxation) or partial (subluxation).
Luxation of the Lens. In this condition the lens is completely dis-
placed, either into the vitreous or into the anterior chamber. Where
luxation into the vitreous has taken place the eye behaves like an aphakic
one, and, if no further complications be present, the patient can see well
with the correcting glass, but unfortunately complications generally ensue,
such as secondary glaucoma, and the eye is often lost. The old method of
cataract operation, still practised by some native Indians, consisted in
depressing the lens into the vitreous, so-called " couching." A luxation
nto the anterior chamber is easily recognised, and the lens, when trans-
parent, looks as if a drop of oil were lying in the anterior chamber, the
upper edge appearing often of a golden hue.
Subluxation of the Lens. The lens may be partially displaced vertically
or horizontally, or it may be tilted, so that one edge of it looks somewhat
forward, and the opposite one somewhat backward.
Diagnosis of Displacement. The lens is the chief support of the iris,
and when it is withdrawn from any part the latter becomes tremulous over
that area on movement of the eyeball. This is best determined by directing
the patient to look upwards quickly, when trembling of the iris over the
subluxated area will be detected. This is characteristic of luxation. An
unequal depth of the anterior chamber is also a prominent sign, and when-
ever this is noted there should be a suspicion of subluxation.
When the pupil is dilated, or, without this, when the displacement is
large, the edge of the lens can be recognised by transmitted light as a
semilunar dark shadow, and also by focal illumination, the aphakic part of the
pupil appearing quite black, whilst the other part appears faintly grey.
THE CRYSTALLINE LENS. loi
Til is arises from the fact that a normal transparent lens reflects some light,
so that a normal pupil is not quite black, but of a very dark grey, and this is
most readily seen in large subluxations.
The aphakic area of the pupil is highly hypermetropic, and the area
over which the lens extends is generally myopic, owing to the curvature of
the lens being at its highest, because of rupture of the suspensory fibres.
In "luxation" the anterior chamber is deep, and the iris very tremulous,
and sometimes the lens can be detected by transmitted light lying in the
vitreous.
Causation. ^^This may be congenital, and then it affects both eyes, the
lens as a rule being drawn upwards. Acquired dislocation develops as the
result of trauma or spontaneously.
Traumatic Dislocations. These are generally caused by contusion of the
eyeball, and all degrees may be produced, from a slight subluxation of the
lens to a complete displacement.
Spontaneous Dislocation. This arises from a gradual softening of the
zonule, which occurs as a rule in high degrees of myopia, choroiditis, and
detachment of the retina.
Treatment. Where the dislocation is so great that a part of the pupil
is aphakic, we may correct the aphakic portion with a convex glass, or the
other portion with a concave, according to which gives the better visual
acuity. Often so much irregular astigmatism is present as to render the
wearing of glasses useless.
VITREOUS HUMOR.
Chapter IX.
GENERAL DESCRIPTION.
The vitreous is a transparent, colourless, gelatinous mass which fills the
posterior cavity of the eye, and occupies about four-fifths of the interior of
the globe. On its anterior surface it has a depression the fossa patellaris
in which rests the posterior surface of the lens. By its other aspects the
vitreous is applied to the ciliary body, retina and optic nerve. This
transparent jelly-like substance consists of a clear fluid enclosed in the
meshes of an equally transparent reticulum, in which are scattered a few
modified connective tissue cells known as the vitreous corpuscles. It is
enclosed in a structureless envelope called the hyaloid membrane, which
lies in close' apposition to the pars ciliaris retinae or retina proper. At the
disc the union is firmer than elsewhere ; at this spot, in foetal life, the
hyaloid branch of the retinal artery runs forAvards through the vitreous to
the back of the lens. Though the artery disappears before birth, jet the
canal in which it ran remains, persisting as a lymph channel, and called the
canal ot Stilling.
In front of the ora serrata the hyaloid membrane becomes thickened
and strengthened by radial fibres, and it is now called the zonule of Zinn,
or suspensory ligament of the lens. The zonule has radial folds, presenting
a series of alternate furrows and ridges. The ciliary processes project into
and are firmly adherent to the furrows, whilst the ridges are applied to the
interciliary depressions, but separated from them by a series of lymph
spaces, Avhich may be regarded as diverticula of the posterior chamber,
with which they communicate. As the zonule approaches the lens it splits
up into two chief layers ; a thin posterior layer, which covers that portion of
the hyaloid membrane lining the fossa patellaris, and a thicker anterior
lamina, which blends with the lens capsule around the equator, some of the
fibres running in front, and others behind the latter. The suspensory liga-
ment retains in position the lens, whose convexity varies inversely with the
degree of tension of the ligament.
The vitreous is avascular, and depends for its nutrition on the blood
vessels of the uveal tract, especially those in the ciliary body. Cnlike the
aqueous, fresh vitreous is never generated, and a loss of vitreous occasioned
by a penetrating wound is rapidly replaced by aqueous. If the amount be
small, sufficient aqueous is secreted to keep the tension of the eyeball
THE VITREOUS HUMOR. 103
normal, but if a large quantity of vitreous be lost, the supply of aqueous
fails to meet the demand, the eye becomes soft and shrinks, and even-
tually sight is destroyed.
Clinical examination. The vitreous is, in health, transparent, but
diseased conditions manifest themselves as opacities. These, unless attached
and fixed to the adjacent retina or ciliary body, float about in the vitreous,
since its pervading reticulum or network has become destroyed. The opacities
change their position with every movement of the eyeball, and they appear
to the patient as one or many dark specks or filaments which float in front
of the eye, moving independent of it. This is practically characteristic of
vitreous opacities, for in no other media do they appear to have such
independent movement.
Focal illumination. Only an opacity stationed so far forwards as to lie
immediately behind the lens can be seen bj^ focal illumination, and it would
appear as a whitish body, situated deeply in the e^^e.
Transmitted light. A plane mirror and a low illumination should always
be used, as a bright illumination renders the detection of fine vitreous
opacities very difficult. Whilst standing at some distance from the patient
the light IS thrown into the eye, while the patient looks upwards, down-
wards, and then straight in front. The opacity will be seen as a black
object moving irrespective of the eye. To examine it in greater derail the
patient must be approached as for a direct ophthalmoscopic examination,
using a + 6 D to + 10 D lens. Very fine vitreous opacities can only be
detected by the plane mirror, and when more minute still they only produce
a fogging of the fundus, but in these cases the patient complains of dimness
of vision, not of specks before the eye. When floating specks are complained
of, the vitreous n ust be most carefully examined before concluding that they
are only muscse volitantes.
Persistent Hyaloid Artery/. This artery, which runs before birth from
the central retinal artery to the lens, supplying nourishment to the latter,
may persist after birth. It is very rare for the persistent artery to contain
any blood, though occasionally a pulsating stump may project into the
vitreous. It usually appears as a greyish tag, of varying length, attached
by one end to the disc or to the lens, the other lying free in the vitreous.
The vision in these cases is generally subnormal.
Affections of the Vitreous. ^The vitreous being avascular (without
blood) and almost structureless, it cannot become inflamed in the oi-dinary
acceptance of the term, and the changes observed are degenerative in
nature, often consisting of bodies floating about, and are secondary to
affections of the choroid, ciliary body or retina.
When a patient complains of motes or bodies floating in his field of
vision, it has to be decided whether they are physiological (muscaj volitantes)
or pathological. Musca* volitantes occur in normal eyes, as they merely
represent the oi-dinary cells in the vitreous, which under certain conditions
become obvious to the eye in which they exist, and the patient most
fi*equently observes them when looking up in the light or against a white
I04 THE VITREOUS HUMOR.
surface, especially when his lids are partially closed, as on waking in the
morning. They may appear under the form of transpai-ent filaments, or of
small, clear, bead-like bodies hanging together, perhaps in rows or clusters,
which move not only with the eye, but also spontaneously. They do not
interfere with vision, and are most frequently complained of by myopes.
Careful examination of the vitreous, both by a plane mirror and by a
+ 6 D to + 10 D lens, fails to disclose to the observer any opacity, when the
symptoms are caused by these physiological cells, as the latter are trans-
parent, whilst bodies not normally present in the vitreous (pathological),
can be detected by the observer, as they are opaque.
PatJiological Vitreous Opacities. These consist generally of particles of
lymph or exudate deposited here in the course of inflammation of the
ciliary body, choroid or retina, but the larger opacities are often due to
haemorrhages from the neighbouring vessels taking place into the vitreous.
They are variable in number and shape, and are seen floating before the
field of vision, shifting with each movement of the eye. The resulting
disturbance of vision, if present, depends partly upon the number of
opacities present, and partly upon the disease of the fundus giving rise to
them. When the opacities are very minute and numerous, they can only be
seen by a plane mirror and a low illumination, dilatation of the pupil being
often also necessary. The opacities appear like dark dots or filaments or
membranes floating about in the vitreous. Sometimes the opacities are so
minute that they can no longer be perceived as distinct points, merely an
obscuration of the fundus being observed ; or they may appear as a faint,
cloud-like opacity slowly descending in front of the pupil, and best observed
after the patient has made a few rapid up and down movements of the
eye, looking then straight in front. The larger opacities can be seen and
examined in greater detail by using a -I- 6 D to -)- 10 D behind the ophthal-
moscopic mirror.
In synchisis scintillans, particles of a silvery or golden hue are seen,
falling like a shower of gold to the bottom of the eye, when the latter,
after rapid movements, is held still.
Muscse volitantes must not be confounded with scotomata, which are
fixed blind spots in the field of vision, due to a loss of sensibility of a
portion of the retina.
The treatment of vitreous opacities is that of the causal lesion. The
patient must be discouraged from constantly looking for them, and the
general health toned up.
Liquefaction of the Vitreous and Lynchisis. This is diagnosed when
opacities can be seen freely floating about in the vitreous, for the frame-
work, in order to admit of this, must have been destroyed. This condition
is always the result of disease of the adjacent membranes, and is one of the
precursors of a detached retina. Later the vitreous may diminish in volume,
as evidenced by a lowered tension of the eyeball.
THE VITREOUS HUMOR.
105
Kmmorrhage into the Vitreous. This may be due to rupture of the
vessels of the ciliary processes, or to those of the retina or choroid. In the
last case the blood must, of course^ break through the retina in order to
reach the vitreous. The blood is absorbed very slowly from the vitreous, but
it gradually shrinks and becomes paler, appearing by transmitte-d light
either as a dark mass or as filaments floating about. The blood ruptures
the framework of the vitreous, and the latter exhibits a tendency to shrink,
rendering a detachment of the retina a not unlikely consequence.
io6
GLAUCOMA.
Chapter X.
GLAUCOMA.
Tiiis is the name given to the group of symptoms caused by an excess ot
intra-ocular tension. It is essentially a disease of advanced life, occurring
generally in patients over fifty, a large proportion of these being hyper-
metropes. When glaucoma occurs independently of any other affection of
the eye, it is called primary glaucoma, but when due to previous eye
diseases it is known as secondary glaucoma.
A gradual increase of intra-ocular tension, if long continued, causes the
weakest part of the eyeball to give way and bulge backAvard. The weakest
part is where the optic nerve pierces the globe, as only the inner layers of
the sclera (the lamina cribrosa) are present here, the outer layers being
continued backwards along the optic nerve, forming one of its sheaths. The
choroid ceases at the optic nerve entrance. The lamina cribrosa recedes
and bulges backwards, and at the same time the optic nerve fibres, which
are attached to it as they pass through, also become stretched and recede.
As the result of this stretching, the nerve fibres gradually become atrophied,
causing a diminution of vision, and if this has set in blindness gradually
supervenes, even though the tension be reduced to normal by operation or
otherwise.
An increased intra-ocular pressure causes some vascular disturbance,
owing to the large veins (the vense vorticosse) taking a much more oblique
course in their passage through the coats of the eyeball than the arteries,
consequently the increased pressure compresses the veins more than the
arteries, so causing a greater interference with the outflow than the inflow
of blood. In a gradual increae of tension this is compensated for by a
corresponding dilatation of the long anterior ciliary veins, which, like the
arteries, pierce the coats, near the corneal margin, in a straight manner,
and so the blood escapes more readily by these channels than by the venae
vorticosse. (Fig. 43.)
The anterior ciliary veins are seen beneath the conjunctiva running
from the corneal margin towards the fornix, and, when dilated, constitute
an omen of some significance. A sudden increase of tension causes an
immediate obstruction in the vense vorticosse, and, as the time does not
allow of a compensating dilatation of the anterior ciliary veins, the blood
GLAUCOMA. 107
escapes with difficulty from the eyeball. The veins become engorged, and
as a result the circulation of the lymph through the cornea is interfered
with, causing the latter to have a steamy appearance, like glass which has
been breathed upon,
Friinary Glaucoma. All degrees of severity are encountered, varying
greatly in the rapidity of their progress. It may be so acute as to destroy
vision in the course of twenty-four hours, or so chronic as to continue for
months or years before such a termination occurs. It is, however, always
progressive, unless checked by therapeutic or surgical measures.
For convenience of description, this condition is sub-divided into acute
glaucoma and chronic glaucoma, but the latter may at any time take on an
acute course. The symptoms of acute glaucoma may be divided into
(1) Those which occur before an acute attack is actually experienced
(premonitory symptoms).
(2) Those which accompany the actual attack.
Premonitory symptoms are seldom absent, though they are frequently
unheeded by the patient. Slight attacks of dimness of vision, lasting only a
short period, are not uncommon, the patient complaining of a fog or mist in
front of the eyes, supervening often after prolonge<:l use of them. A fre-
quent symptom is an increasing impairment of accommodation, necessitating
a lens for near work of greater strength than the age would justify, it
being often necessary to increase the strength of the lens, perhaps several
times, in the course of a few months, which should always remind one of
the possibility of glaucoma. Artificial lights, such as gas or electric light
appear at times to have a coloured ring around them.
The premonitory stage may last only a few weeks, or be protracted over
months or years, but in the latter cases the eye presents those changes seen
in chronic glaucoma.
The acute attack is ushered in by intense pain, sudden in onset,
often radiating from the eye to the forehead, ears or teeth. Simultaneously
the sight rapidly diminishes, the patient only being able to recognise hand
movements The eye appears violently inflamed, both ciliary and conjunc-
tival injection being present, the cornea cloudy and insensitive to
touch. The anterior chamber is shallow, and the pupil dilated and ntore or
less immobile. No details of the fundus can be seen, and the tension of the
eye is greatly increased. The determination of the tension is performed by
palpating the eyeball through the upper lid as follows : The patient, with
head erect, looks well downwards, and the tips of both forefingers are placed
above the tarsal cartilage in the lid, and gentle pressure is made on the
eyeball by one forefinger, whilst the other appreciates the amount of dis-
placement of fluid which the pressure occasions. Normal tension is
designated Tn, and increased tension T-!-, whilst diminished tension is
written as T . Immediate operation must be resorted to, or vision will be
permanently lost.
io8 GLAUCOMA.
Sometimes the attack is not so severe (sub-acute glaucoma), the symp-
toms and clinical signs being similar, but less severe. The instillation ot
eserine will in these cases cut short the attack.
Chronic Glaucoma, or Simple Glaucoma. In this condition the increase
of tension occurs so very gradually that no inflammatory signs are produced.
The symptoms are those of the premonitory stage of acute glaucoma. Slight
pain and a feeling of pressure in the eyes, aggravated by overwork, worry or
a debilitated state of general health, are not unusually complained of.
Although the visual acuity may be more or less normal until late in the
course of the disease, yet the field of vision early becomes contracted, often
commencing on the nasal side, but occasionally it partakes more of a circular
contraction. Colour vision remains good until late in the disease, in
contra-distinction to optic atrophy in which affection diminution of the
colour field easily develops.
The patient frequently complains that he has to employ stronger and
stronger glasses to see his near work; a rapid increase of presbyopia
through diminution of the power of accommodation, should always excite
suspicion of this affection. Later in the disease the vision becomes greatly
reduced, eventually complete blindness, more or less, supervening. Glau-
coma affects both eyes, one later than the other, and is met with in
emmetropia and myopia, but most frequently in hypermetropia about
middle age of life. It may also occur in young people.
Clinical Signs. ^^The eye looks quite normal externally, except that the
anterior ciliary veins, which run backwards from near the corneal margin to
the fornix, appear more prominent and distended. The anterior chamber is
rather shallow, and the iris looks thin and attenuated. The pupil is some-
what dilated a rather unusual occurrence in elderly people^ and only reacts
sluggishly to light. The media are clear, and the tension is more or less
normal. The above signs, by no means definite, may be seen in
normal eyes, but it is the ophthalmoscopic appearance of the disc which
decides whether the case be glaucomatous or not.
Ophthalmoscopic Examination. In the early stage the margins of the
disc are regular and well defined, but later choroidal changes around the
disc are found, the latter being surrounded by a yellowish or whitish areola,
the bluish- white lustre of the disc contrasting with the white atrophic area,
and preventing the latter from being mistaken for the disc proper. The
excavation (cupping) is the most characteristic ophthalmoscopic sign, and
this always extends to the margin of the disc, though at first the whole of
the disc may not be involved, but only a part. In that part, however, its
cupping extends to the edge of the disc, whilst a physiological cupping
ceases before it reaches the margin. Later the whole disc becomes deeply
cupped, and on the floor of the excavation may be seen the grej' dots of the
lamina cribrosa. The cupping is recognised by parallactic displacement, or,
in the direct method, by the fact that when the edge of the disc is in focus,
the disc itself is only indistinctly seen, owing to it being in a more posterior
plane, the substitution of a concave lens being necessary in order to see the
papilla clearly (ID = 0.3 mm. in depth. The blood vessels do not emerge
at the centre of the papilla, but close to its inner margin. In deep
Plate IV.
A 'LONGITUDINAL SECTION OF NORMAL PAPILLA Stained with Wei'grerfs stain,
which colours medullary sheath and blood black.
Note. Cessation of medullary sheath at lamina cribrosa, and contraction of nerve as it
passes, also interruption of choroid at nerve entrance. No excavation, and
central nerve fibres do not pass over to periphery until their exit.
B Ditto, with large cential excavation owing to central fibres passing: over to periphery.
Lamina cribrosa not displaced.
C PATHOLOGICAL CUPPING (Optic atrophy).
Note. Shallow cupping: involves the whole of the disc, lamina cribrosa being normally
situated.
Z>. PATHOLOGICAL CUPPING (Glaucoma).
Note. Deep cupping: involving the whole disc, lamina cribrosa being displaced backwards.
Plate V.
./.-NORMAL PAPILLA SEEN OPHTHALMOSCOPICALLY.
Note Central physiolosrical cupping paler than rest of disc, with stippling of lamina
crihrosa. The black ring is due to choroid, but it is rarely so distinct as this.
R-PAPILLA IN GLAUCO.MA.
Note. Whitish halo around mar(;in of disc, colour of which is bluish white- Cupping of
vessels extends to mar((in of disc, arteries being rather small and veins dilated.
C- PAPILLA IN OPTIC ATROPHY.
Note. Ed(fe of disc well defined, vessels small, disc white, and cupping: extends to edge
of papilla.
GLAUCOMA.
109
excavations the vessels cannot be seen ascending the sides of the cup, as
they are hidden from view by the overhanging margin, so that those visible
on the floor are lost to view as they ascend the side, and reappear, changed
in number and position, as they bend round tlie margin of the disc to gain
the retina.
When associated with staphyloma posticum (myopic crescent) the
glaucomatous cup is larger in diameter than usual, appearing oval instead
of round, and the sides of the cup are more sloping (not so steep) than in the
ordinary glaucomatous cup. The lumen of the arteries is smaller than
normal, whilst pulsation may be observed in them, or, if not, slight pressure
made by the finger on the globe during ophthalmoscopic examination will
cause pulsation to appear. Retinal arterial pulsation is very significant of
glaucoma. The retinal veins are more dilated than usual, and pulsation in
them is frequently observed, but this also may occur in healthy eyes.
The colour of the disc in glaucoma varies from a bluish white, in the
earlier stages, to a greenish white later, and the floor of the cup presents
the grey dots of the lamina cribrosa.
Three kinds of excavation of the disc are differentiated, and their dis-
tinctive signs are as follows. (Plates lY. and V.) :
Physiological Cupping.
Edge of disc normal.
Blood Vessels, of usual calibre,
are seen ascending on the
inner wall of the cup. No
iirterial pulsation is observed
but venous pulsation may
be present.
The excavation ni.iv be deep or
shallow and ir.clude a small
or the larger part of the disc,
but it doe> not extend to the
margins of the papilla.
The cupped area is whiter than
the rest of the disc, the latter
appearing of a reddish color
by contrast. At the bottom
of the cup is seen the greyish
Atit'pling of the lamina
cribrosa.
The lamina cribrosa is in its
normal ptisition.
Glaucomatous Cupping.
In later stages a ring of
choroidal atrophy is seen
around the disc.
.Ai teries are smaller but the veins
are dilated, and the vessels
seem to arise from the nasal
margin of the disc. Arterial
pulsation is commonly ob-
served, as also is venous.
The excavation is deep, and at
first may not include the
whole of the di.sc, but it
always extends to the margin
of the papilla.
The whole disc appears of a
bluish white colour, though,
in the later stages it >eems
of a greenish hue. The
stippling of the lamina
cribrosa is well seen.
Atrophic Cupping.
(Primary Atrophy of Neri'e.J
Edges well defined.
Blood vessels small and con-
tracted
Excavation is shallow saucer
sh;iped and extends to the
margin of thj disc.
The disc appaars quite white,
and the lamina cribrosa is
clearly discernible.
The lamina cribrosa is pushed The lamina cribrosa is in its
back, lying more posteriorly normal position,
than usual.
Diagnosis. ^Though the symptoms in middle-aged people of transient
obscurations, or coloured rings around lights, or an increasing abnormal
impairment of accommodation, or ocular headaches associated with bilious
attacks, are suggestive of glaucoma, especially when the anterior ciliary
veins are dilated, and the anterior chamber is shallow, yet its absolute
diagnosis depends upon the presence of cupping. Where the latter affords
no certain clue, the fields of vision for form or colour should be taken when
the above symptoms are present. In glaucoma the contraction of the field
no GLAUCOMA.
generally commences in the nasal half, and the colour field presents a
restriction corresponding with that of the form fields, whilst in optic atrophy
the peripheral colour vision, especially for red and green, is markedly
deficient. In glaucoma the light minimum is said to bt^ deficient, whilst the
light difference is not far from normal, but practically this examination
is so difficult to conduct as to render the res^ults unconvincing.
Cause of Glaucoma. In order to understand the nature of glaucoma, it
is necessary to be conversant with the anatomy of the anterior chamber, and
the function of the aqueous humor, as the rise in tension in the eyeball is
chiefly due to either increased production of aqueous or interference with
its exit. At the corneo-scleral margin, the inner lamellgp of the cornea
break up into bundles of fibres, which chiefly afford attachment to the
ciliary muscle, though a few are continued around the angle of the anterior
chamber into the substance of the iris. These radiating and anastomosing
bundles of elastic fibres are called the ligamentum pectinatum, and they are
covered Avith endothelial cells continuous with those covering the posterior
surface of the cortiea. These cells only form a lining to the bundles, and do
not stretch across the intervals betAveen them, the aqueous freely com-
municating with the spaces between the bundles of the ligamentum
pectinatum. These spaces are called the spaces of Fontana, and they com-
municate with another large space situated a little in front of them, close
to the corneo-sclerotic junction, and called the canal of Schlemra, or sinus
circularis iridis. This canal of Schlemm communicates on the one hand with
the aqueous chamber through the spaces of Fontana, and on the other hand
with the anterior ciliary veins in its immediate vicinity.
The aqueous hurnor supplies nutrition to the adjacent parts, and forms
a fluid bed to allow for the free movement of the iris. It is largely secretea
by the ciliary processes, and flows firstly into the posterior chamber,
passing through the pupil into the anterior, and escaping from the anterior
chamber into the anterior ciliary veins through the spaces of Fontana and
the canal of Schlemm.
There are other lymph paths within the eye by which' its nutrient fluid
can escape, as the perichoroidal space between the choroid and sclera, and
the canal of Stilling in the vitreous chamber, both of which empty
posteriorly into the lymph channel of the optic nerve sheaths, but the
anterior lymph circulation through the anterior chamber is by far the most
important, and it is to obstruction of these paths that glaucoma is due.
The intra-ocular pressure is largely a matter of balance between the
inflow and lhe outflow of ocular contents, as the internal capacity of the
envelopes remains more or less the same. Though tlie intra-ocular pressure
would be raised by an increased inflow unless there was a corresponding
increased outflow, yet it is most probable that the cause of ordinary
glaucoma is due simply to an interference with the outflow.
Priestley Smith has shown that the circumlental space diminishes as age
advances, owing to the continuous growth and enlargement of the lens, and
when the ciliary body is also large, as in hypermet ropes, this space is still
GLAUCOMA. Ill
further encroached upon. As a result the iris is pushed forwards, especiallj'
towards the ciliary margin, where sometimes at the periphery it is in
contact with the posterior surface of the cornea, thus closing the source of
exit for the aqueous humor, and, as a consequence, increased tension in the
eyeball results.
Henderson, of Nottingham, in a recent book, combats the above
volumetric theory of glaucoma. His conception of the me<'hanism of intra-
ocular pressure is based upon Leonard Hill's discovery that the pressure
within the skull is equal to, and varies directly with, the pressure of the
blood in the intra-cranial veins, and that the intra-ocular pressure is equal
to the intra-cranial, s) that they rise and fall together. This Hill demon-
strated experimentally. Intra-ocular pressure, according to this theory, is
not dependent upon the relation of inflow of contents and outflow, but is
vascular in origin, the pressure being equal to the lowest venous pressure,
viz., that in Schlemm's canal, and varying directly with it. The free
contact between aqueous and veins causes the intra-ocular pressure to be
maintained at that of the blood in Schlemm's canal. In glaucoma the contact
is diminished, and the intra-ocular fluids, being contained in an unyielding
capsule, act as a rigid volume, which compels the circulation to run in
rigid lines. Now, in a rigid system the outflow pressure is always higher
than in a similar system of elastic tubes, and in glaucoma the circulatory
pressure is that in a rigid system, and therefore the intra-ocular pressure is
maintained at a corresponding high level. Henderson maintains that the
aqueous is not secreted by the so-called ciliary glands, but oy cells lining the
apices of the ciliary processes, and that it pas.^es into the anterior ciliary
veins by an active process of resorption, neither the inflow nor outflow
of aqueous being a passive filtration, and he also asserts that the cornea
is nourished by aqueous diffusing through the ligamentum pectinatum.
Treatment. In acute glaucoma the operation of iridectomy is urgently
indicated, and, if performed early, a good result is frequently obtained. In
simple glaucoma rest to the eyes and abstention from near work is impera-
tive. Myotics, as eserine, are instilled into the eye, the resulting
contraction of the pupil tending to keep the angle of the chamber more
patent, though if such contraction is not obtainable, operative measures are
suggest<l. but these do not give such good results as in the acute attack. A
large portion of the iris may be removed (iridf^tomy), or an attempt may be
made to create a scar by excising a portion of the sclera, which will admit
of the filtration of the aqueous into the subconjunctival tissue.
Secondary Glaucoma. By this is understood an increase of tension
appearing in the course of other diseases of the eye, and as a conse-
quence of them. The clinical picture is similar to that of primary glaucoma,
modified by the additional signs of the causal disease. It is a common
complication of irido-cyclitis, due either to the pupillary border of the iris
being bound down to the anterior surface of the lens (seclusio pupillse),
thus preventing the flow of aqueous from the posterior to the anterior
chamber, or to the more viscid nature of the aqueous humor resulting from
cyclitis, which hinders its percolation through the spaces of Foutana.
112 GLAUCOMA.
Dislocation, partial or complete, occasionally causes acute glaucoma, as
also do retinal or choroidal haemorrhages and intra-ocular tumors.
In all cases of glaucoma, especially when occurring in younger people,
present or previous eye disease must be carefully excluded.
BuPHTHALMUS (ox eye). This is a disease of childhood, in which the eye
becomes of an unusual size. It arises from obliteration of the angle of the
anterior chamber, and as a consequence the intra-ocular pressure rises,
causing a gradual expansion of all the coats of the eyeball, the latter not
having the resistive powers which they possess later in life.
Diminution of the intra-ocular pressure is a sign that the contents of the eyeball
have diminished in volume, and is generally the result of previous disease. It is
commonly associated with detachment of the retina.
113
IHE CHOROID.
Chapter XI.
ANATOMY.
The choroid, ciliary body and iris together form the uveal tract, whose
function, owing to the numerous blood vessels it contains, is chiefly con-
cerned with supplying nutrition to the internal parts of the eye. The
choroid forms the post-erior two-thirds of the uveal tract. It is interposed
between the sclerotic and retina, and commences anteriorly at the ora
serrata where the ciliary body begins. It forms a continuous deeply-
pigmented coat, except at the optic nerve entrance, where it is absent in
order to allow the entrance of the nerve into the globe. Thicker behind
than in front, the outer surface is flocculent, and connected to the sclera by
a loose areolar tissue ^the lamina fusca which serves to transmit the ciliary
nerves and the long ciliary arteries as they pass to the ciliary body.
The choroid consists of blood vessels and branched pigment cells
imbedded in a loose connective tissue, and is described as presenting from
without inwards tliree layers
(1) Lamina suprachoroidea, or fusca described above.
(2) The choroid proper.
(3) A thin transparent membrane called the membrane of Bruch. This
layer lies next to the retinal pigment layer, from which it is produced, and
so it is really a part of the retina.
The choroid proper consists chiefly of blood vessels and pigment cells,
the former being so arranged that the smallest the choroid capillaries lie
most internal and next to Bruch's membrane, and the largest are placed
most external, lying adjacent to the lamina fusca. They collect the blood
into four or five main trunks the venae vorticosse which pass out of the
sclerotic near the equator of the globe, and empty the blood into the
ophthalmic vein. The arteries are derived from the short posterior ciliary,
which pierce the sclera around the optic nerve entrance.
The pigment of the choroid is most dense in its external layers, gradu-
ally diminishing towards the retina, the choroidal capillaries and Bruch^s
membrane being entirely devoid of it. It is situated between the blood
vessels in variously shaped cells arranged irregularly. The choroid is not
well supplied with nerves, so that inflammation of the structure is not
accompanied by pain.
114 THE CHOROID.
The retinal pigment layer and the outer retinal layers are dependent
upon the choroidal capillaries for their nourishment, the retinal artery
only supplying the innermost layers of the retina.
The choroidal vessels can be readily distinguished ophthalmoscopically
from the retinal as below :
Choroidal. Retinal.
These are flat and ribbon shaped, and These are rounder, and branch in an
branch in an irregular manner, the arborescent manner, but the branches
branches freely anastomosing- with do not anastomose with one another,
each other. No light reflex is A light reflex is present, running
present. along the centre of the vessel.
Congenital Abnormalities of the Choroid.
Coloboma of the Choroid consists in an absence of the choro.d, and is
most commonly situated in the midline of the floor of the fundus, running
backwards from near the optic nerve entrance to the ora serrata. It
appears ophthalmoscopically as a sharply defined white patch, its edges
commonly being bordered with pigment ; the retinal blood vessels often
run around the edge instead of pursuing their ordinary course, which would
be across the coloboma, this distinguishing it from an old choroiditis, in
which the retinal vessels run in the normal way. The coloboma varies
greatly in size, and is sometimes associated with a coloboma of the iris. Most
frequently the coloboma is limited to a small patch below the disc, called
Fuch's coloboma, which has the ophthalmoscopic appearance of a myopic
crescent, except that it is situated below the disc instead of external to it,
and in this condition a diminished visual acuity is always present.
Albinism.- In this abnormality there is a lack of pigment, not only in the
eye, but also in the rest of the body. The child has very flaxen hair, with
white eyebrows and lashes, and vision is poor, nystagmus (slight rapid move-
ments of the eyeball) often being present when any attempts at fixation are
made. The iris is light grey, and appears reddish by transmitted light.
Owing to the small amount of pigment present in the retinal pigment layer
and in the choroid, the vessels of the latter are seen ophthalmoscopically
coursing and interlacing over the white background of the sclera.
Albinism is congenital and inherited, and all degrees exist, from a
complete absence of pigment to only a slight diminution.
PATHOLOGY
Inflammation of the Choroid Choroiditis. We divide this into two sub-
divisions, according to whether the inflammation leads to the formation of
pus or "matter (suppurative choroiditis) or results only in the escape of
lymph (exudate) from the vessels (non-suppurative or exudative choroiditis).
The former condition is rarely met with, except when caused by a pene-
trating wound of the eye, the resulting inflammation involving all the
structures, and as a consequence complete destruction of the globe not
uncommonly results.
THE CHOROID.
"5
Nonsuppurative or Exudative Choroiditis. When choroiditis is spoken
of, this is the form which is alluded to. It may be circumscribed in
extent or diffuse, and even spread so far forwards as to involve
the ciliary body and iris (choroido-iritis), or, again, it may commence in the
latter and spread backwards to involve the choroid. This is not surprising,
as really the iris, ciliary body and choroid form one continuous whole.
The retina is also fre<iuentiy involved (retino-choroiditis), for it
principally receives its blood supply from the choroid, and so any affection of
the latter must disturb its nutrition and cause changes in it. The eye
looks normal, and the disease manifests itself to the patient only through
some disturbance in'^ight, which varies in degree accoixling to the part of
the fundus affected, and is recognised only by ophthalmoscopic examination,
except when the iris and ciliary body are also affected. In the latter case
the objective signs of iridocyclitis will be present, as posterior synechia,
keratitis punctata (K.P.), and fine vitreous opacities.
The ophthalmoscopic appearances differ in a recent choroiditis from
those in a chronic case :
Recent Choroiditis.
The tiindus is a little indistinct owing lo
minute vitreous opacities.
Retinal blood vessels are more or less
engorged, but they pass in front of
the affected area, in contradistinction
to retinitis.
The choroiditic patch is of a greyish
white colour, and slightly laised
above the level of the rest of the
fundus. Its margins are ill defined
from the surrounding retina, and
no choroidal vessels are seen.
The greyish white patch is due to an
infiltration of the choroid with
exudate, which hides the red of the
choroidal vessels, and the overlying
retina is clouded and grey, covering
the subjacent choroidal patch as with
a faint veil.
Old Choroiditis.
Fundus generally clearly seen.
Retinal blood vessels normal, passing in
front of the choroidal patch.
The choroidal patch is white, with per-
haps pigmentary deposits scattered
irregularly through it, or more
especially around its border, which
is clearly cut and well defined from
the rest of the retina. Remains ot
choroidal vessels can be frequently
seen coursing through the white
patch, and the latter lies generally
slightly below the level of the rest of
the fundus.
The white patch is due partly to scar
tissue, as the choroid has been
destroyed by the inflammation, and
partly to the sclera showing through.
Choroiditis is very chronic in its course, taking many weeks for the
patches of exudation to be converted into scar tissue, but in slight cases
the exudate occasionally becomes absorbed by the surrounding tissue, instead
of destroying the latter, the choroid then returning to the normal again.
Choroiditis is a very common disease, and is observed at all ages. It is
often met with in general diseases, such as syphilis, anaemia, etc., but it is
also frequently caused by small collections of pus in different parts of the
body, such as the nose, teeth, breast, etc., the poison of which enters the
blood stream and irritates the choroid.
Myopia is frequently complicated with choroidal changes ; in fact, it is
rare to find a normal choroid in the higher degrees of myopia. These
ii6 THE CHOROID.
choroidal changes are atrophic in nature rather than inflammatory, and are
due to the stretching which the choroid must necessarily undergo when the
entire posterior segment of the sclera bulges backwards (posterior staphy-
loma), as is the case in high myopia.
The treatment of choroiditis consists chiefly in the eradication of the
cause. In a recent attack the eyes must be rested and protected from the
light by dark glasses. Hot fomentations and leeches applied to the back of
the ear relieve the engorgement of the blood vessels, and tend to promote a
more rapid healing.
Syphilitic Choroiditis. Though syphilis may cause many different types
of choroiditis, yet the following ophthalmoscopic changes are characteristic
of it. Appearing at first around the periphery of the fundus are white
circular spots of different sizes, having a punched-out appearance. Their
margins are lined, with pigment, and the more recent may have a yellowish-
red appearance, differing little from the rest of the fundus, and very likely
to be overlooked unless the fundus is carefully examined. As time advances,
they gradually become whiter. Occasionally, instead of white patches with
pigmented borders, there may appear spots of pigment surrounded by a
pale margin, the retinal vessels, of course^ running in front of these areas.
Also the pigmented epithelium layer lessens all over the fundus, exposing
to view the vascular network of the choroid, with here and there small
islands of pigment between them. The changes are most marked in the
early stages in the periphery of the retina, but later all the fundus is
attacked. This condition is commonly called disseminated choroiditis
(Plate VI.) Another common syphilitic affection is retino-choroiditis, in
which the retina appears cloudy, owing to fine dust-like opacities in the
vitreous, and circumscribed ill-defined exudates are indistinctly seen in the
retina and choroid. Later a picture like that of retinitis pigmentosa is
presented.
Senile Choroiditis. In old people a chronic choroiditis, often occurring
in both eyes, and limited to the macular region, is not uncommon. The
choroid in the macula is dotted over with minute black or yellowish white
specks, looking as if it had been dusted with a mixture of pepper and salt.
This condition must not be confounded with Tay's choroiditis.
Myopic Choroiditis. The choroidal changes in myopia partake more of
the nature of a thinning (atrophy) rather than an inflammation of the-
choroid, owing to the enlargement of the posterior third of the eyeball.
Posterior Staphyloma or Myopic Crescent. This condition is recognised
by the ophthalmoscope as a white crescent at the outer side of the papilla.
The posterior bulging of the eyeball causes atrophy of the choroid at this:
place, and it sometimes extends all around the disc. The crescent at first
merely appears of a lighter colour, later becoming white, with pigment
around its border. This lies at a slightly lower level than the contiguous-
parts of the fundus, as will be manifested by parallactic displacement.
Occasionally two or three contrasting zones exist in the staphyloma, lying;
at slightly different levels, and differing from each other in their pigme^ita-
tion, the recent zone being less pale in colour and at a slightly higher leve*
Plate VI.
/I. -DISSEMINATED CHOROIDITIS.
Noic. More or less circular whitish areas with pigmented borders. Atrophy of retinal
pig^ment layer has not taken place yet, so that choroidal vessels cannot he seen.
B. Ditto (more advanced stage, a pc>rtion only of fundus being shown).
Note. Well-defined edges and varying pigmentation of affected are.
crossing light patches,
course over them.
Choroidal vessels
They are broader and Hatter thin retinal vessels which
C.-RUPTURE OF CHOROID.
Note. The rent is concentric with disc, with retinal vessels in
characteristic, with butf colored inlge.
front of it. Its shape is
For use of srifnii of the Fundus phUes tve are indebted
to the />to/>rietors of " Haab\ Atlas of Ophthalmoscopy"
THE CHOROID. 117
than the others, thus showing that the formation and enlargement of the
staphyloma have taken place at different periods. If the crescent is indis-
tinctly defined from the adjacent healthy choroid, it presumes an increase
in the myopia, and the case should be seen at short intervals, and near
work more or less suspended, whilst if the border is clearly defined and
perhaps lined with pigment, the inference is that the myopia is not
progressing.
Macular Changes in Myopia. This should always be carefully looked for,
as the region of the yellow spot is very liable to be involved in the higher
degrees of myopia. Slightly lighter-coloured spots are often the only signs
at first observed, and these gradually become paler, and tend to coalesce,
forming later on rather large whitish areas, with a varying amount of
pigmentation in them. Haemorrhages are not uncommon in the macular
area, owing to the rupture of a blood vessel in the stretched choroid, and
commonly, in high degrees of myopia, a coal-black round spot appears in
the macula, which may become as large as the size of the disc.
Detachment of the retina, and vitreous opacities arising from the
myopic condition^ are dealt with in Chapters IX. and XII.
Degeneration of the Choroid. In old people, especially if their eyes
have been diseased, small white slightly-raised bodies, about half the size of
a pin-head, are seen scattered singly or grouped in little masses, especially
about the macula lutea, or between it and the disc. Vision may or may not
be affected. It is frequently called Tay's choroiditis, and is due to
degenerative changes in Bruch's membrane.
Bupture of the Choroid. This expression is used to denote a tear in the
choroid coat when accompanied by no changes in the sclera, and is not
applied to perforating wounds involving the choroid. It is caused by a
severe blow on the eye, and the rupture invariably occurs at or near the
posterior pole, as the globe is less supported here. Immediately after the
injury the blood escapes into the vitreous, and prevents a clear view of the
fundus, but when this has cleared up the rent in the choroid is seen as a
sharply-defined jagged streak, over which the choroidal vessels cross. This
is due fo the edges of the laceration separating from each other, allowing
the white sclera to be seen between them. (Plate VI.) One or more
of these linear splits may be observed, but they all lie in the neighbourhood
of the posterior pole, usually on the outer side of the disc, and are more or
loss vertical in direction, presenting a slight concavity towards the papilla.
Treatment chiefly consists in bodily as well as ocular rest.
Detachment of Choroid. ^This very rarely occurs. It appears ophthal-
moscopically like a detached retina, except that the choroidal vessels would
also be distinctly seen.
Tumors of the Choroid. ^These are generally malignant, and they at
first appear ophtlialmoscopically as a detachment of the retina, which differs
from the ordinary kind by the fact that the upper part of it is solid, and
appears fairly well defined, but if any new blood vessels or haemorrhages are
present over this area, no doubt can exist as to the nature of the affection.
ii8 THE CHOROIU.
The lower part of the detachment is often only an ordinary serous one, and
arisen owing to the disturbance of the choroidal circulation by the growth.
All detachments occurring in normal eyes without any history of injury
must be viewed with grave suspicion, and in doubtful cases removal of the
eye is indicated, as it is wiser to sacrifice that rather than incur any risk
to life.
There is no difficulty in recognising this affection in its late stages, as
the growth invades the vitreous and the other structures of the eyeball.
119
THE RETINA.
Chapter XII.
ANATOMY.
The retina is a delicate membrane containing the terminal end organs
of the fibres of the optic nerve, supported by a connecting framework. It
lies between the choroid and the hyaline membrane of the vitreous humor,
and extends from the optic disc to the ciliary processes, presenting at the
latter a finely indented border, the ora serrata. Here most of the indi-
vidual retinal elements cease, but they are continued over the ciliary body
as a layer of columnar cells, forming a lining to the layer called the pigment
epithelium of the retina, which is also continued on to the ciliary body and
iris, constituting those previously described layers, the pars ciliaris retinse
and the pars iridica retinse. The retina diminishes in thickness from 0.4mm.
around the optic nerve entrance, to 0.2mm. anteriorly. It is everywhere
easily detached from the subjacent choroid, except at the ora serrata. In
the living eye the retina is perfectly transparent, and of a purplish-red
colour, the latter depending upon the visual purple present in the rods,
but after death it rapidly becomes opaque, appearing as a frail white
membrane. Pathological changes in the living retina manifest themselves
as opacities, and are easily recognised as such by the ophthalmoscope.
Fig- 56.
PiR^merUed epithelium of human retina (viewed from the surface).
Viewed from the front, the retina presents at its posterior pole a small
yellowish spot, the macula lutea, which is somewhat oval in shape, its long
axis being horizontal, and measuring from 2 to 3 mm. In its centre is
found a small depression, called the fovea centralis. About 3 mm. to the
I20
THE RETINA.
nasal side of the macula, and about 1 mm. below its level, is a whitish
circular disc of about 1.5 mm. diameter, the optic disc, which corresponds
with the entrance of the optic nerve. The circumference of the optic disc is
generally slightly raised, whilst its central portion is depressed, forming the
optic cup.
The retina consists of two parts, having different functions. These are:
(a) The nervous part; (6) the sustentacular or sustaining part, which pro-
vides a framework for the nervous elements.
The nervous part, or retina proper, consists of many layers, arranged as
follows from choroid to vitreous: (1) The pigmentary layer, (2) the rods
and cones, (3) the outer granular layer, (4) the outer molecular layer,
(5) the inner granular layer, (6) the inner molecular layer, (7) the ganglionic
layer, (8) the nerve fibre layer.
Ftg' 57-
Diai^rammatic section of the human retina.
A The pigment layer. B Rods and cones. C External limiting: membrane. D Outer
granular layer. E Outer molecular layer. F Inner granular layer. G Inner molecular
layer. H Ganglionic layer. K Nerve fibre layer. L Internal limiting membrane.
(1) T/ie pigmentary layer bounds the retina ext-ernally, and is developed
from the outer lamina of the optic vesicle. It consists of a single layer of
six-sided (hexagonal) cells, whose outer part contains a nucleus and is
THE RETINA.
121
devoid of pigment. (Fig. 56.) The inner part is loaded with pigment
granules, and it has a narrow, long tail extending into the region of the
rods and cones. Immediately external to this pigmentary layer, separating
it from the choroid, is a thin homogeneous membrane the membrane of
Bruch which is a product of the pigment cells.
(2) The layer of rods and cones. These constitute the most important
layer, and they are placed at right angles to the plane of the retina. The
rods extend externally as far as the pigment layer, and are cylindrical in
form. The cones are shorter, thicker, and swollen at their inner extremity,
whilst externally they end in a tapering filament, which does not quite reach
the pigment epithelium. Both rods and cones are divided into two segments,
an outer and inner. The outer rod segments are cylindrical in shape, and
are unaffected by stains, but they have a remarkable tendency to split up
into highly refractile superimposed discs, like a pile of coins. They are of a
purple colour, owing to the visual purple or rhodopsin which they contain.
The outer cone segments are similar to the outer rod segments, except that
they contain no visual purple, and are conical in shape. The inner seg-
ments of both rods and cones are singly refractile, stain readily with
carmine, and are larger in diameter than the outer segments, but they
taper towards the end.
A A cone and two nxis from the hiunnn retina. B Outer part of rod separated into discs.
(3) The outer granular layer {outer nuclear). On entering this layer,
each rod almost immediately becomes a fine tapering fibre extending down
for a variable distance, expanding to enclose an oval transversely striated
nucleus, and then continuing on as a fine nodulated fibre to enter the next
layer. Each cone enters as a thin filament, and immediately surrounds a
nucleus, continuing on into the next layer as a nervous fibre, but slightly
broader than that of the rod.
122 THE RETINA.
(4) The outer molecular layer contains the terminations of the rod and
cone fibres, the former ending in small knob-like expansions, and the latter
in broad bases or feet. Both the^e endings are surrounded by a network of
fibrils, which are connected with the cells in the next layer.
(5) The inner granular layer (inner nuclear) contains two varieties of
largo nerve cells. One the bipolar cell has two tail-like processes, one
passing up to the preceding layer, and the other in the opposite direction.
Each ascending process ends either around the button-like process of a rod
in the preceding layer (rod bipolar), or around the foot-like process of a
cone (cone bipolar). There are also many horizontal cells in this layer.
(6) The inner molecular layer consists chiefly of the descending processes
of the bipolar cell of the previous layer, and ascending branches of the cells
in the following layer, each branching up into numerous ramifications.
(7) The ganglionic or nerve cell layer consists of a single layer of large
oval-shaped cells, which, on their outer side, give off numerous branches
running into the inner molecular layer, and on their inner side give off a
single fibre, which chiefly forms the next layer.
(8) The layer of nerve fibres or stratum opticum consists chiefly of the
nerve fibres given off by the nerve cells in the preceding layer, and which
collectively form the optic nerve at the disc, conducting the retinal sensa-
tions to the brain. There are also a few fibres carrying impressions from
the brain, and ending in the inner nuclear layers.
The sustentacular fibres support the nervous structures, and extend from
within outwards through the thickness of the retina as far as the bases of
the rods and cones. These fibres begin on the inner surface of the nerve
fibre layer in the form of expanded bases, by the apposition of wliich a
delicate membrane, the membrana limitans interna, is formed. The
fibres pass out to the outer ruclear layer, where they break up into a
network of fibrils surrounding the rods and cones, forming the membrana
limitans externa.
This complicated structure of the retina is practically a series of nerve
fibres, with nerve cells interpolated between them, and arises owing to the
visual impressions being formed in the cells in the outer portion of the
retina (rods and cones). The various nerve fibres conduct the!=e impressions
via the optic nerve to the brain.
The yellow colour of the macula is due to the presence of pigment in
the inner layers of the retina. At the circumference of the macula the
nerve fibre layer is greatly thinned, and the rods are few in number, but
the ganglionic layer is much thickened, possessing from seven to nine
strata instead of only one, as in other parts of the retina. At the fovea
centralis the retina is thinner still, as here its nerve fibre and ganglionic
laj^er are absent. There are no rods, and the cones are crowded together,
but the pigment layer is thicker.
THE RETINA. 123
At the ora serrata the retinal nervous elements suddenly cease, the layer
ot rods and cones first failing. In front of the ora serrata the retina is
prolonged over the ciliary processes in the form of two layers of cells : (a) an
inner layer of columnar cells, representing all the retinal layers except the
pigmentary, (6) an outer layer, consisting of the retinal pigment layer. The
two together form the pars ciliaris retinae, and these two same layers are
prolonged over the back of the iris, where both are pigmented, forming the
pars iridica retinae.
Vessels of the Betina. The retina is supplied by the arteria centralis
retinae, a branch of the ophthalmic artery, which pierces the sheath of the
optic nerve about J in. behind the eyeball, and makes its appearance in the
centre of the optic disc. Here it divides into an upper and a lower
branch, and each of these again bifurcates into an internal or nasal, and an
external or temporal branch. The resulting four branches ramify towards
the periphery of the retina, and are named the superior and inferior
temporal, and the superior and inferior nasal arteries. The temporal arteries
pass outwards above and below the macula, to which they supply branches,
but these do not extend so far as the fovea centralis, which is devoid of
blood vessels.
The larger blood vessels run in the nerve fibre layer near the limitans
membrana internans, and they send branches which penetrate as deep as
the inner granular layer, from which the veins arise. The latter accompany
the arteries, being generally placed to their outer side. The retinal arteries
are terminal, as no anastomosis or connection takes place between the
various branches, this having an important bearing in cases of arterial
obstruction, for death of that part of the retina supplied by the obstructed
artery takes place, as its blood supply is totally cut off. The retinal
arteries only nourish the inner layers of the retina, whilst the outer derive
their nourishment from the choroid, the macular area being chiefly sup-
plied by the choroid capillaries.
PHYSIOLOGY.
When light falls upon the retina, certain changes of a mechanical,
chemical and electrical nature are produced. The pigment of the pigment
epithelium cell, together with its fine process, moves forward to embrace the
outer segment of the rods and cones, the pigment cells becoming acid in
reaction, accompanied by bleaching of the visual purple of the rods.
Besides these physical and chemical actions there are also definite electrical
changes, and though it is admitted that the above changes take place under
the influence of light, yet their relative significance is much disputed.
Purkinje's figures and Mariotte's experiment with the cross or dot prove
that the images are formed behind the nerve fibre layer, and probably in
the rods and cones. As only the latter are present in the fovea centralis,
their appreciation of form is much greater than that of the rods. In order
that two points may give rise to separate visual impressions, their images
must be at least 0.003 mm. apart, for since this is approximately the
diameter of the macular cones, images which are nearer together would
only stimulate one pone, and so give rise to a single visual impreesion.
124 THE RETINA.
Both rods and cones are capable of producing the sensation of hght, but
the response to the sensation of colour probably lies only in the cones. The
nature of the transformation undergone by the ethereal vibrations in the
rods and cones is still hotly disputed, some favouring an electrical change,
some a photo-mechanical, and others a photo-chemical, but the resulting
nerve stimuli are conducted by the nerve fibres to the brain, where their
interpretation takes place. Each rod and cone receives light from one
point in the visual field, and from one only, and this correspondence
between the element excited and the position of the point from which the
light proceeds enables us to judge of the relative position in space of these
points. Our judgment, however, receives some unconscious support from
other senses, and many sensations which seem to be simply visual such as
those of size, distance and solidity are in reality complex, and depend to
a certain extent on the teaching of experience, on muscular sense, which
tells us the position our eyes are in, on the amount of convergence and
accommodation used, and on a comparison with well-known objects. For
distinct vision the image must fall on the fovea centralis, and this is called
central or direct vision, whilst when it falls upon any other part of the
retina it is called indirect or peripheral vision, but in low degrees of
illumination the fovea is less sensitive than the surrounding parts.
In order that the two retinal images of an object may give rise to a
single visual impression, it is necessary that the images should fall on
corresponding retinal areas, and the upper halves of both retinae correspond,
as also do the lower, but the nasal side of one corresponds with the temporal
of the other, and vice versa. Our visual sensations are of three different
kinds, inasmuch as in looking at objects we take cognisance of their form,
colour and brightness. The faculty by which we recognise the form of
objects is called the space sense, which finds its numerical expression in the
visual acuity. The faculty by which we distinguish colours is known as the
colour sense, and that by which w^e distinguish different degrees of bright-
ness is named the light sense. These three faculties are appreciated in the
retina, but in different degrees, throughout its extent, and a distinction is
made between central and peripheral vision.
Central vision is that of the fovea centralis, and will not be treated of
in this book.
Peripheral or indirect vision is given by the remaining portion of the
retina, exclusive of the macula. This is, of course, less sensitive for form
than the macula, but movement and slight differences of luminosity are
detected by it more quickly. The field of vision is investigated by the peri-
meter, or, in a rough manner, by the hand, which is useful for detecting the
more gross limitations in the field, and the test can be easily and rapidly
carried out. One sits at the same level, directly in front, and at a short
distance from the patient. The opposite eyes (R. and L., or L. and R.) of
patient and observer are closed, and the open eyes look, and continue to
look during the whole time, directly at one another. The observer moves
his hand from the periphery inwards in the four principal meridians at an
equidistance between himself and the patient, and if the latter's field be
THE RETINA. 125
normal, both the observer and he will see the hand at the same distance.
This is a very useful procedure, and, where no perimeter is available, will
often afford valuable evidence in cases of suspected glaucoma, etc.
The normal field does not extend equally in all directions, but it reaches
furthest to the temporal side (over 90), and is much less extensive at the
nasal and upper parts of the field, due partly to the projection of the nose
and eyebrows, and also partly to the fact that the outer and lower parts of
the retina are less practised in seeing than are the upper and inner parts,
and consequently their functions are less developed. The field extends
outwards 95, upwards about 53, inwards about 47, and downwards
about 65.
The field for colour varies according to the size and intensity of the
coloured squares used, and when large and bright these will be distinguished
up to the extreme limits of the field, but when examination is made with
coloured squares of paper 1 to 2 cm. in diameter the most peripheral parts
of the retina are found to be colour blind. The visual field for blue is the
largest, yellow being next, then red, green being the smallest. The
examination with colours is a more delicate test than with white, and
further, it gives some information as to the nature of the lesion, for a lesion
of the percipient elements (rods and cones) causes a diminution of the field
for blue, whilst a lesion of the conducting elements (affection of the optic
nerve, such as toxic amblyopia) causes a diminution in the perception of
red and green.
The pathological alterations of the visual field consist in its contraction,
or there may be gaps, called scotomata, which lie like islands within the
field of vision. The contraction of the field may be more or less equal all
round, and we then call it a concentric contraction. When contraction is
considerable, as in retinitis pigmentosa, and also occasionally in glaucoma,
even though central vision be good, the patient experiences great difficulty
in walking about alone, owing to his only seeing those objects which lie
directly in his line of vision. This can be personally experienced by
fastening a long tube in front of the eye, permitting of little more than
direct vision, when the importance of peripheral vision in orientation will be
appreciated. The contraction of the field is sector-like in detachment of
the retina and embolism of a retinal artery.
Scotomata are distinguished according to whether they are perceived
entoptically (positive scotoma) or not (negative scotoma).
A positive scotoma is a dark spot which the patient perceives in his
visual field, and its cause may lie in the refracting media or the retina, the
opacities in the media casting shadows upon the retina and becoming
visible as dark spots. If the opacities are in the vitreous, they move
independently of the eye, and are called motile scotomata. Fixed scotomata
originate either from opacities in the cornea or lens, or from changes in the
fundus, and they are most readily perceived when gazing at a uniformly
bright surface.
126 THE RETINA.
A negative scotoma is one which is not perceived by the patient, but
only discovered when the visual eld is examined. It is called absolute
when all perception of light is deficient within the limits of the scotoma,
and relative when it is limited merely to non-recognition of colour.
THE FUNDUS OF THE RETINA.
The normal appearance of the fundus presents so many variations as
to necessitate a detailed account of them, in order to prevent their confusion
Avith pathological conditions.
In the examination of the fundus with the ophthalmoscope the various
parts must be observed in the following systematic order: (1) The disc.
(2) The macula. (3) The outer, inner, upper and lower paiis of the retina.
(1) T/ie Disc. In order to bring this into view, the patient's eyes must
be directed horizontally about 15 inwards. In the indirect examination
this is attained by directing the patient to look at the observer's ear. The
following points with regard to the disc should be noted : (a) The size and
shape ; (6) the margin ; (c) the blood vessels ; (d) the relationship of the
plane of the disc to that of the adjacent part of the retina ; (e) the colour.
The shape of the disc is generally circular in outline, but in astigmatism
it appears oval, with its long axis in the direction of the meridian of
greatest refractivity, thus, when the astigmatism is with the rule, the disc
appears as a vertical oval by direct ophthalmoscopic examination. The
papilla or disc often has, in reality, an oval form, and in order to dis-
tinguish whether we are dealing with a disc that is anatomically oval, or
with astigmatic distortion of a round papilla, we must resort to a com-
parison with the inverted image. If the disc is really a vertical oval in
shape, it must also appear so when viewed by the indirect method, but if
the shape be an astigmatic effect, then the distortion, as seen by the
indirect, will be the opposite to that as viewed by the direct, viz., a trans-
verse oval. This only applies when the convex lens is held close to the
patient's eye.
The size of the disc apparently varies a great deal, due to the different
degree of enlargement under which the papilla is seen, for the true size of
the papilla in enucleated eyes is almost always the same about 1.5 mm. in
diameter.
The margin of the disc is generally clearly cut and well defined, though
it is not unusual to find the nasal margin a little obscured, because of the
greater number of nerve fibres which happen to cover it.
Surrounding the disc, we often recognise two narrow rings of different
colour. The inner one, lying next to it, is white, and is called the scleral
ring, its white colour being due to the sclera, which is here exposed to view.
It is present when the canal in the sclera, through which the optic nerve
passes, is narrowest, not at the retinal end, as is generally the case,, but a
little posterior to that, so that the canal, as viewed from the front, forms
XI funnel, with the base forwards. The Avail of this funnel, being formed of
THE RETINA.
127
white sclera, is seen by the ophthalmoscope as a narrow white ring. The
choroid, at the optic nerve entrance, has frequently an excess of pigment,
appearing as a black narrow ring, sometimes complete, and at others incom-
plete, around its disc. (Plate V.)
The blood vessels of the disc consist of the retinal artery and vein.
They divide at the head of the nerve into two chief branches, an upper and
lower, but various other branches may be given off. (Fig/ 59.)
The ophthalmoscopic differences between retinal arteries and veins are
easily detected :
The arteries are of a bright red color,
small, and are generally straight.
In the larger arteries a shining white
streak is seen running along the
centre of the vessels.
The veins are darker, of greater calibre,
and pursue a more crooked course.
The light streak is not commonly seen in
the veins, and if present is indistinct.
A V
C.'iD
^^i- 59-
Blood vessels of the disc.
A Artery. V Vein. G Scleral ring. Z) Choroidal ring.
The artery is usually to the nasal side of the vein, and on leaving the
disc the vessels commonly cross one another, either vessel passing in front of
the other. This causes some pressure on the under vessel, slightly obstruct-
ing it, as is manifested by the dilated condition of the vessel peripherally to
the crossing. Sometimes the vessels are observed winding around one
another, or one forms a loop through which the other passes. Occasionally
a cilio-retinal vessel is seen emerging from the disc (Fig. 60), this arising
from the short posterior ciliary arteries, which form in the sclera around
the optic nerve a small arterial ring, the latter frequently sending a branch
to the optic nerve.
A rarer physiological aberration is a persistent hyaloid artery. In
foetal life this artery runs from the retinal artery, through the vitreous, to
the posterior surface of the lens, to which it supplies nourishment. At
about the seventh month it should disappear, but occasionally it persists,
either in its entirety or the central part only disappears, leaving an
attenuated portion attached either to the capsule or the disc. In the latter
case it is recognised ophthalmoscopically as a thin and more or less opaque
filament, arising from the retinal artery and running forwards, its terminal
128 THE RETINA.
end lying free, in the vitreous. Its lumen is generally obliterated, hence
no blood is present in it. If the persistent part be attached to the posterior
capsule of the lens, the ophthalmological picture is the same, but the fila-
ment is traced running backwards into the vitreous. If an object is pro-
jecting forwards into the vitreous, we may determine it by substituting
Fig. 60.
From the lower and outer margin of the papilla arises a cilio-retinal artery A, making a
hook-like bend. The upper retinal vein is seen crossing in front ot the artery, whilst the
inferior artery lies in front of the vein.
increasing powers of convex lenses, or, in myopia, by inserting weaker
convex lenses (direct ophthalmoscopy), and if, when the rest of the fundus
is indistinct, the object is distinctly seen, it must be lying in front of the
retina, and the stronger the convex lens, or the weaker the concave, with
which the object can be seen, the further forwards is it stationed. A
difference of level of about 1 mm. corresponds to a difference of refraction
of 3 D.
PHYSIOLOGICAL ABNORMALITIES.
Vascular Pulsation. The human heart empties itself (beats) about 7^
times per minute. Each beat is accompanied by a corresponding dilatation
of the arteries to accommodate the increased volume of blood, and this may
be recognised by the finger as a pulsation wave in any of the superficial
arteries of the body, viz., the radial at the wrist, or the temporal in front
of the ear. In the smallest arteries and capillaries the pulse Avave is so
feeble as to defj' detection, and usually in the veins no pulsation at all is
present. Pulsation is recognised ophthalmoscopically in the retinal vessels
by an alternate expansion and contraction of their walls, or, if one of the
vessels be distinctly curved, as when bending over a physiological cupping
of the disc, a slight to and fro movement is seen in the vessel.
Venous pulsation is commonly seen in the retinal veins in healthy eyes,
though very rarely present in other veins of the body.
Bonders gives the following explanation of the venous pulse. At
each beat of the heart an additional quantity of blood is driven into the
arteries of the interior of the eye, causing a temporary raising of the intra-
ocular pressure, and the latter compresses the veins on or near the disc, as
THE RETINA. 129
the blood pressure in the veins is not only lowest there, but also the vein
commonly makes a dip down into the physiological cup. The blood in the
vein becomes dammed up, but it rapidly accumulates, and as the venous
pressure rises, it is at last able to overcome the compression, allowing the
blood to flow on.
This venous pulsation is most readily recognised on the disc, where
the vein dips backwards. An arterial pulsation is rare in health, but is
commonly seen in glaucoma, and, when present, should always excite sus-
picion of the latter disease. The pulsation is only seen in the large arteries
near the disc. In som forms of heart disease and in exophthalmic goitre
(in which disease the eyes are very prominent) arterial pulsation is often seen.
The relationship of the plane of the disc to thai of the adjacent part of
the retina is such that normally the optic nerve lies on the same plane as
the rest of the fundus, or very slightly in front of it.
The disc may lie below the level of the fundus, and is then spoken of as
" cupped." This cupping is of two varieties, and it is necessary to be able
to discriminate between them. (Plate IV.)
(1) Physiological Cupping. As the name implies, this is normal, of no
significance, and arises owing to the central fibres of the optic nerve
beginning to separate and crowding over to the border or margins of the
nerve before they reach the disc. It is recognised ophthalraoscopically by
the fact that the cupping does not extend to the margins of the disc, but is
confined either to a central part, involving a small or the greater portion
of the disc, or to a section of the peripheral part. Such cupping is com-
monly situated in the outer half, and may extend as far outwards as the
margin. It appears whiter than the rest of the disc, and at the bottom of
the excavation, in deep cupping, are seen greyish dots, the lamina cribrosa,
giving it a mottled appearance.
The retinal vessels generally ascend on the inner side of the cup, and
the brilliant white of the cupping forms a vivid contrast with the reddish
hue of the unexcavated portion of the disc, but the condition is confirmed
by noting parallactic movement. Differences of level of the various parts of
the fundus are easily appreciated by this parallactic movement, obtaine<l
either by the direct or indirect ophthalmoscopic examination.
To render manifest any cupping of the nerve the observer, in the direct
method, fixes any vessel on the disc, preferably a small one, and then makes
slight movements of the head at right angles to the direction of the
vessel, keeping the latter in view all the time. If the vessel lie only in on
plane, the whole of it appears to move in the same direction and at the
same rate as the observer's head ; but if a portion of the vessel be in a more
posterior plane, that part appears to move at a quicker rate than the
remaining portion of the artery, but in the same direction. The more
posterior the vessel (the deeper the cupping), the quicker the movement.
The slightest difference in depth is detected by this method, and it is
important that all opticians should be conversant with it. If the cupped
130 THE RETINA.
part of the vessel be looked at, then the other portion appears to move m
the opposite direction to the observer's movements, but this is not so ens\
of detection as the former.
Differences of level of the fundus are also made apparent in the
inverted image by moving the convex lens, which serves for the production
of the inverted image, a little up and down during the examination. If
the points of the fundus fixed upon all lie in the same plane, they do not
change their relative position to each other with the movement of the
convex lens. If, on the contrary, a difference of level exists between them,
then a displacement with relation to each other is noted, as at one time
they approach nearer to one another, and at another they become further
apart.
In pathological cupping of the disc, the whole of the latter is involved,
right up to the edge of it. This represents often the only ophthalmoscopical
difference between physiological and pathological excavations. Patliological
cupping is seen in optic atrophy, where it is shallow and saucer-like, and
also in glaucoma, where, in the later stages, it is very deep.
Ophthalmoscopic differences between the three kinds of cupping
(Plate V.):
Physiological.
Involves only a portion of the
disc.
The cupping may be shallow or
very deep.
The excavated part white, the
other of good color.
Vessels emerge from disc
generally slightly to inner
side of centre, and are of
normal size. Venous pulsa-
tion occasionall}^ present.
Opi/c Atrophy.
Involves the whole.
Shallow.
Disc white.
Vessels normal in position,
but of small size.
Glaucoma.
Involves the whole.
In the early stages shallow, in
the later deep.
Disc often normal in colour, even
in later stages.
Vessels arise close to inner
margin of disc. The arteries
are small arid the veins dis-
tended. Venous pulsation
is common and sometimes
arterial pulsation is also
The normal colour of the disc varies greatly, from a lightish grey to a
yellowish red, so that little reliance can be placed upon it for the recognition
of pathological changes. To a large extent its colour is dependent upon
that of the neiglibouring retina, for instance, when the nerve fibres are
opaque, the disc appears red by contrast. Tlie excavated portion in physio-
logical cupping is whiter than the rest of the disc.
(2) The Macula. This is a little more difficult to see than other parts of
fundus, oAving partly to the greater contraction of the pupil, caused by the
projection of light on to the macular area, and partly to the annoying
light reflexes, but both these difficulties are surmounted by practice, and
the macula should then be easily seen without a mydriatic. To obtain any
details the direct examination must be used. If the observer is in the
proper position, it is only necessary for the patient to look straight at
him a movement of the eyes only, not of the head in order to bring the
macula into view. This region lies at about the same level as the disc, and
approximately the width of a disc and a half to its outer side. If one is
Plate VII.
/f.-NORMAL FUNDUS OF A FAIR MAN.
Note. VVdl defined disc, with inner white scleral and outer hiack choroidal ring. Arteries
liffhter and smaller th.in veins. Physiolotfical cupping of whiter colour. Macular
a darkish red citcular area. Over all the Hatter and wider choroidal vessels, with
no central reflex, branching irregularly, and freely anastomosing with each other.
/?. -NORMAL FUNDUS.
Note. Disc not so clearly defined. Retinal arteries smaller and paler than veins. No
cupping. Macular a circular area. Choroidal vessels are not seen, owing to
retinal pigment layer h<;ing well developed.
C.-MYOPIC FUNDUS.
Note. - Posterior staphyloma invests the disc, which is bordered by pigment. BufF colored
mottling of macular area caused by partial atrophy of choroid, characteristic of
early myopic changes. Also recent haemorrhage.
D. Ditto, more advanced.
Note. BufF colored spirts replaced by irregular pigmentation, with whitish streaks from
atrophy of choroid. Diminution of retinal pigment allows choroidal vessels to be
seen as light colored lines.
THK RHTINA. 131
unable to see the macula in this position, it is best to look slightly outwards
through the nasal portion of the cornea, whilst the patient's eyes are also
directed a little out, or, Avitli the patient's eyes turned well out, the
observer transmits the light, in an inward direction, through the other part
of the cornea. The macular area is generally well defined from the rest of
the funduSj owing partly to the greater contraction of the pupil, caused by the
shape. The colouring is deepest around the centre of this area, but in the
centre itself a small white or yellowish spot is seen. The macular area is, in
size, about half that of the papilla, and is devoid of blood vessels.
Occasionally, especially in fair people, the macula api)ears to be com-
posed of minute yellow and black points, and this stippled appearance is
due to irregular pigmentation of the pigment epithelium of the retina.
Many varieties of light reflexes are seen in the different maculae, an<l
they can be recognised as such by the fact that their shape and position
vary with the movements of the mirror. Sometimes the reflex appears very
bright and of a circular shape, and this is termed a "bull's eye" macula,
owing to its similarity to the light of a policeman's lantern.
(3) The Upper, Lower, Inner' and Outer Parts oi the fundus must also be
examined. The red glare of the fundus is due to reflection from the
choroidal circulation, and not to the presence of the retina, which is trans-
parent. We recognise the latter mainly by ils blood vessels, which are
prominently in view as they course over the red background, and also in
some cases b}- a faint greyish striation, due to the nerve fibre layer, the
latter being most readily seen in dark people. In Europeans this is mostly
confined to the immediate neighbourhood of the disc, but in the negro races
it is seen all over the fundus, giving the impression of a transparent veil
lying in front of the choroid. In children, markedly so in hypermetropes, a
white shimmering reflex, termed a " shot silk retina," is commonly seen.
It is most plainly observed along the course of the vessels, and is easily
distinguished, as the reflexes change their place Avith every movement of
the mirror.
Though the red background of the fundus is due to the blood circulating
in the choroidal vessels, the latter are hidden from view by the retinal
pigment layer. The more pigmented the latter is, the darker appears the
fundus, sometimes even appearing almost grey, whilst the lighter the
pigment, the brighter is the red of the fundus.
The choroidal vessels are, however, seen physiologically under two con-
ditions :
(1) Where the retinal pigment is not very abundant, while that in the
choroid is plentiful, being chiefly placed in the interspaces between the
choroidal vessels. The fundus appears dividtyi up into irregular elongated
islan^ls, with bright red striee running between them, the latter being the
choroidal veins, which are seen to anastomose (unite) tiHHily with each other.
The retinal vessels are easily seen running over the choroidal veins. This
type is physiological. It is called a " tesselated fundus," and is liable to be
confused with disseminated choroiditis by beginners.
132 THE RETINA.
(2) In very fair people, especially albinos, the pigment, both in the
retina and choroid, is so scanty as to permit of the choroidal vessels being
plainly seen. (Plate VH.) The retinal vessels, lying in front of the
choroidal, are easily distinguished from them.
Retinal vessels. Choroidal vessels.
Situated in front of the choroidal. Passing behind the retinal.
They appear round, are sharply defined. They appear flat, ribbon-like, and not
and have a bright reflex streak well defined. No reflex streak is
running along the centre. present.
They branch in an arborescent manner, They branch in an irregular manner, and
and the divisions do not anastomose freely anastomose with one another,
with one another.
It should be noted that : To see the upper part of the fundus, by the
direct method, the patient looks up; to view the lower, down. To see the
macular region, he looks outwards ; and the nasal, inwards. The patient
turns his eye in the direction of the field to be observed.
CONGENITAL ABNORMALITIES.
Opaque Nerve Fibres. An ordinary nerve consists of central fibres
(along which the nervous impulse travels) enclosed in a sheath called the
medullary sheath. The fibres of the optic nerve possess this sheath as far as
the lamina cribrosa, but lose it on approaching the latter, thus entering
the eye without one. (Plate IV.) The nerve fibres are transparent, but the
medullary substance is opaque, and occasionally some of the optic nerve
fibres, after passing through the lamina cribrosa, regain their medullary
sheath, and a characteristic ophthalmoscopic appearance is presented.
The medullated fibres, being opaque, appear as brilliant white glistening
streaks, radiating from the disc in a fan -shaped manner, the periphery of
the opaque area often having a distinct flame-like appearance. (Plate IX D.)
The fibres are generally at the upper and lower borders of the papilla, but
occasionally they surround it, the disc appearing, by contrast, of a dark
red hue.
The inexperienced might mistake this condition for choroidal atrophy,
but the snowy whiteness and flame-shaped appearance of the fibres are very
distinctive, and when a retinal blood vessel is seen passing under the fibres
(in choroiditis the retinal blood vessels are, of course, in front of the white
patch), no doubt can exist as to the nature of the ophthalmoscopic picture.
The retina is insensitive over the site of these fibres, and, if large enough, a
definite scotoma can be mapped out with the perimeter. The visual acuity
is often, for no apparent reason, slightly reduced in these cases. The only
treatment is the correction of the refractive error.
CricTc-dots. ^These are a series of highly refractile dots around the disc,
lying in front of the retinal vessels. They are of no significance, but
are often found in several members of the same farilily.
THE RETINA. 133
ANOMALIES OF VISION.
Hypercesthesia of the i^etina is manifested by an increased sensibility to
light, and is often associated with overwork. The patient complains of
flashes of light, and a sensation of heat and fatigue in the eyes. Intolerance
to light is frequently a prominent symptom. Objective examination is
negative, and the treatment consists in the prescription of proper glasses
and attention to general health.
Amblyopia. This is a term applied to defective vision where no visible
lesion in the eye is present to account for it. Amblyopia ex-anopsia arises
from prolonged non-use of one eye, and is usually associated with
strabismus. The media and fundus are healthy, and the field of vision
normal, but even with the proper correction the visual acuity is fre-
quently only g"^ No squint may be observed, but, on questioning the
patient, a history of previous squint is nearly always elicited. No treatment
is advisable, as, though the acuity may be increased by the more or less
constant use of the affected eye, yet binocular vision is unattainable. If
the patient be young (under ten), then efforts should be made to create
binocular vision.
Amblyopia from Exposure, to Bright Light. The effects vary according
to the length of exposure to and intensity of the glare. In the least severe
cases the light causes a temporary paralysis of the retina, lasting a variable
time, from a few .seconds to several hours in cases of momentary exposure,
as is seen after flashes of lightning, or after the glare from snowfields. No
objective signs are seen, either in the media or fundus.
If the light be very intense, the retinal symptoms may be accompanied
by conjunctivitis, and by abrasions of the corneal epithelium. The con-
junctival and corneal symptoms, as a rule, do not appear until some hours
after the exposure. In the worst cases macular vision may be lost, owing to
atrophic and pigmentary changes occurring in the retina.
Ilemeralopia, or Night Blindness. This is a term applied to any condi-
tion in which the visual acuity is greatly diminished when the illumination
is less, as in the evening. The symptom is caused by (1) peripheral corneal
or lenticular opacities, which, owing to the dilated pupil consequent on the
diminution of light, come into the pupillary area, and cause irregular refrac-
tion, whilst in ordinary illumination the contracted pupil cuts them off
from the pupillary area ; (2) diseases affecting the peripheral parts of the
retina, as retinitis pigmentosa. In the bright daylight the patient sees
fairly well, and experiences no difiBculty in going about, but in the evening
his visual field is so contracted that he is unable to go out alone. These
symptoms are occasionally seen in very debilitated children, when no
ophthalmoscopic changes can be seen.
Nyctalopia. This term is applied to that condition in which the sight is
better in a lessene<l illumination, as at night, than in bright daylight. It
occurs in central opacities of either cornea or lens, as under low illumina-
tion the pupil dilates, and light gains admittance through the peripheral
transparent parts of the media. The diseases of the light-perceiving
134 THE RETINA.
apparatus which cause this condition are those which affect the centre of the
field, whilst the periphery is undisturbed, as in tobacco poisoning. Here the
macular fibres only are affected, an<l so the patient sees better when the
pupil is dilated, as in the evening.
DISEASES OF THE RETINA.
Retinitis. Inflammation of the retina is generally the result of some
constitutional disturbance, as diabetes, syphilis and Bright's disease. The
symptoms are those of disturbance of vision, but it is not uncommon to
find considerable retinal trouble with fairly good or normal vision, especially
Avhen the macular region is not involved. These conditions can only be
diagnosed by ophthalmoscopic examination, as their detection by the peri-
meter, though feasible theoretically, involves such a prolonged and minute
examination as to be practically useless.
Opitthalmoscopic Signs. In recent cases there is a diffused cloudiness of
the whole of the fundus, due partly to the presence of minute vitre-
ous opacities. The outline of the disc is hazy, indistinct, and often
slightly swollen, and the retinal vessels are much dilated, engorged,
and tortuous. Haemorrhages are frequently seen in various parts
of the fundus, and appear as dark red patches, of various shape and size,
which contrast with the brighter red of the fundus. If they are situated in
the nerve fibre layer of the retina, they appear striate or flame-like in
shape (similar to opaque nerve fibres) as the blood spreads along the fibres,
but when the hsemorrhages lie deeper in the retina, or in the choroid, they
are of rounded or irregular shape. The position of the luvmorrhage or any
lesion can also be determined by their relationship to the retinal blood
vessels which run in the nerve fibre layer, for if the vessels can be traced
over the lesion (either blood or exudate), the latter must be deeper than the
nerve fibre layer, whilst if the vessels i-un underneath (as will be evidenced
by their disappearance at the margin of the lesion) the lesion must be
situated either in or in front of the nerve fibre layer. Lymph or exudate
escapes from the engorged vessels, appearing as white patches, varying in
their shape, size and position as the hfemorrhages do.
Retinitis always runs a sluggish course, and though the slightest cases
may cause no permanent injury to the retina, yet the latter is generally
more or less impaired, but the amount of disturbance of vision depends
largely upon the position of the lesion.
The treatment is largely general, and in diabetes early diagnosis is of
great importance, as the ordinary dietary is very harmful. In albuminuric
retinitis the white spots or exudates are often arranged in a radial manner
around the macula, presenting a characteristic picture (Plate YITI.C), but
the haemorrhages are not so numerous as in diabetic retinitis, though the
diagnosis of these conditions is only confirmed by the detection of albumen
or sugar in the patient's urine.
Plate Vlir.
//.-FUNDUS IN RETINITIS PIGMENTOSA (early stage).
Note. Spider shaped spots of pi(jniont on periphery. lying in front of retinal vessels.
/?. Ditto (late stage).
Note. Disc white and atrophic. Retinal vessels small and thread like. Choroidal vessels
as convoluted mass, owing to decolorisation of retinal pigment. Spider shaped
spots encroaching ccnlr;lly.
r.-FUNDUS IN AI.HUMINURK RETINITIS.
Note. Edge of disc hlnrred. Two large and numerous small hccmorrhages. In macule,
exudate arranged in radial manner so distinctive of alhuminuric retinitis.
THE RETINA. 135
Embolism of Betinal Artery. An embolus is a foreign body in the blood
stream (either small blood clot, fat cells, etc.), which, when it reaches a
blood vessel of smaller size than itself, completely occludes the lumen of the
vessel, so preventing the onflow of the blood in it. The retinal arteries are
terminal ones (they do not anastomose with one another), so that part
of the retina supplied by the occluded vessel is cut off from its nourishment,
and gradually dies. The embolus, if large, may block up the central
artery, causing a ^sudden complete loss of vision, or, when small, only one of
the terminal branches may be occluded, and a scotoma in the field of vision
is complained of, corresponding to the affected area. Detachment of the
retina and embolism are the commonest causes of scotoma affecting only
one eye.
Diagnosis is confirmed by ophthalmoscopic examination (1) where the
central artery is occluded, the retinal arteries and veins are narrowed, the
smaller ones being invisible. The retina, Avithin a few hours', dies and loses
its transparency, becoming milky white, especially around the macular area,
whilst in the centre of the macula is often seen a bright cherry-red spot
(Plate IX. C.) After a few weeks the cloudiness disappears, and the retina
becomes transparent again, but is atrophic and functionless. The disc
now appears white, and the blood vessels small, the latter oft^en being
bordered by white lines. The blindness is permanent, and treatment of
very little avail. (2) AVhere only a branch is affected, on tracing the artery
from the disc to the periphery, it will be seen to be normal as far as the
occlude<l spot, when it at once becomes smaller and paler (owing to absence
of blood), being continued on as a thin filamentous thread.
Retiniiis hi^morrhagica. This is caused by a thrombus blocking a vein.
A thrombus is a blood clot which forms when a part of the inner wall of the
vein becomes roughened from any cause Avhatever, and though the clot is at
first slight, yet it gradually grows until it occludes the vessel. The blood
is being continuously pumped into the vein, but it cannot flow back to the
heart owing to this obstruction, so it bursts through the venous wall
into the surrounding tissue. In the letina these hseniorriiages become very
numerous, but they only lie along the course of the obstructed vein, the
latter being enormously distended.
Retinitis pigmentosa. This is a degeneration of the retina, accom-
panied in the later stages by more or less atrophy of the optic nerve. It is
extremely chronic in its progress, commencing at an early age, and gradually
progressing to almost complete blindness in advanced life. In the early
stages the child complains of an inability to see at night, when the illumina-
tion is low (so-called nyctalopia), but sees quite well in the daytime. This
arises owing to the peripheral portions of the retina, the part first affected,
being under-sensitive. Later, the field of vision becomes so contracted,
even in bright daylight, that the patient is unable to go out alone, though
central vision may be quite good. Later on central vision is lost, and
blindness, more or less, supervenes.
The disease attacks both eyes, and as heredity is an important factor in
its production, no treatment influences its progress. In the early stages
136 THE RETINA.
the fundus appears normal, except in the peripheral parts, where numerous
small spider-shaped black pigment spots are seen, the latter being connected
together by their legs. (Plate VIII. A.) No spots of exudations are present.
^ The pigment spots are often situated in front of the retinal vesvsels, and, as
the disease progresses, the pigment is found encroaching more and more
towards the disc. Later the latter becomes pale, owing to atrophy of
the retinae. Wliilst the retina is becoming pigmented in this manner, the
pigment epithelium is becoming more scanty, so allowing the choroidal
vessels to be distinctly seen. (Plate VIII. B.)
These changes arise from the choroidal capillaries (which supply nutri-
ment to the rods and cones and outer layers of the retina) becoming
narrowed, and finally obliterated. As a result the rods and cones do not
receive their proper nourishment, and this leads not only to a diminution of
the pigment in the retinal pigment layer, allowing the choroidal vessels to be
seen ophthalmoscopically, but also to a migration of the pigment cells into
the retina, where they form such a characteristic ophthalmoscopic feature.
Detachment of Retina. By this is meant a separation either partial
or complete of the retina from the choroid upon which it merely lies, being
connected to it only at the optic nerve entrance and the ora serrata. In the
dissected eye it can with ease be separated from the choroid, except at its
two points of attachment. In the living eye the retina is kept pressed
against the choroid by the vitreous, and it may become detached either
Avhen this pressure ceases to act, or when the retina is pushed from its bed
by a force greater than the pressure of the vitreous, as in a choroidal tumor.
The diminution of the vitreous pressure may be due to its escape fol-
lowing an operation or from a wound, but it is more commonly caused h\ a
shrinkage and liquefaction of the vitreous, consequent on a disturbance of
its nutrition. The latter commonly occurs in myopia, and as the sub-retinal
fluid, which collects betAveen the choroid and the retina, looks like yellow
serum, these kinds of detachments are called serous. Far less frequent
are those detachments caused by an active propulsion of the retina away
from the choroid, which may be due to haemorrhage from the choroidal
vessels, or to a choroidal tumor. Serous detachments generally commence
in the upper part of the fundus, bvit the fluid gravitates, and ultimately
settles in the lower part, hence it is most commonly seen here. The
detachments may be slight or extensive, involving a part or the whole of
the retina.
Symptoms. The patient often complains of the sudden appearance of
a sort of cloud obscuring the vision of one eye, and examination of the field
of vision will disclose a scotoma corresponding to the detached poi'tion of
the retina. The vision is affected according to the position and extent of
the detachment, and central vision may be quite normal, if the macula and
its immediate neighbourhood are intact. Its detection is made by ophthalmo-
scopic examination, which presents a distinctive appearance.
Plate IX.
/f.-FUNDUS OF SHALLOW DETACHMENT OF RETINA. INVOLVING MACULAR
REGION.
Note. Dark color and tortuosity of retinal arteries. Slight opwcity of retina inferred
from the i>bsciiralion of choroidal markings seen elsewhere.
/?-FUNDUS OF DETACHED RETINA.
Note. Dark and tortuous vessels with no reflex streak. Retina opaque, and rest oi
fundus not in ftxrus, as detached area was best seen with +5 D.
C. -FUNDUS OF EMBOLISM OF CENTRAL ARTERY.
Note. Arteries narrow, and veins wider than usual. Livss of transparency of marul.-r
area, and the cherry red spot.
Z). -FUNDUS OF OPAQUE NERVE FIBRES.
Note. Disc red hy contr.ust with white patchesof medullated fibres. Retinal blood vessels
both in front and behind patches, which are continuous with disc, and are Hame
shaped at m.irgins.
THE RETINA. 137
Ophthalmoscopic Signs. In the early stages the detached portion of the
retina appears of the same colour as the rest of the fundus, but it gradually
becomes opaque, appearing of a light greyish colour, and of a dull lustre.
The appearance of the blood vessels is most distinctive, as their light reflex
is lost, and they are darker, often appearing nearly black, and more
tortuous (following the folds of the retina) than those on the rest of the
fundus. They also lie further forwards, and so when in focus the rest of the
fundus is out. (Plate IX. A.)
In large detachments there can be seen folds in the retina, the tops of
these showing a whitish sheen. (Plate IX. B.) Treniulousness can be elicited
with movement of the patient's eye.
In a flat shallow detachment no retinal folds nor tremulousness is
present, and the diagnosis rests upon changes in the vessels, which are best
seen at the junction of the detachment with the healthy retina.
In total detachment, the retina lies just posterior to the lens, and is
best seen with a + 10 D. It appears as a whitish, wrinkled membrane,
whose nature is only rendered apparent by the detection of the retinal
vessels coursing over its surface.
By far the commonest cause of a detached retina is myopia, but if the
detachment occurs in an eye otherwise normal, one should always suspect a
choroidal tumor. This spreads so quickly, and is so dangerous to life, that
for successful treatment early recognition is essential. The appearance of
haemorrhage or new blood vessels in the detached area is a conclusive sign
of tumor.
The treatment of detached retina is disappointing. Rest in bed for
six weeks is advocated by some, but the fluid only gravitates to the upper
part, to return again to the lower after the patient has been up some time.
Operative interference, as the introduction of a knife through the sclera
into the detached area, allowing escape of the fluid, occasionally gives a
good result, but if degeneration of the vitreous be present the condition
will recur. The futility of treatment becomes readily appreciated when
we remember that this affection is generally onlv a symptom of vitreoiis
degeneration, the latter being caused by posterior staphyloma (myopia) and
ciliary changes of long standing.
Glioma of Betina. This is a tumor which occurs in early life (from one
to six j-ears). It is very liable to i-ecur, and unless the eye be removed
at once a fatal issue follows. There are no external changes in the eye,
which, except in the very early stages, is quite blind. Later there is
noticeable in the pupil a whitish mass with a lustrous appearance, and it is
this which first attracts the parent's attention, the patient being usually
too young to complain of any disturbance of visual acuity.
38
THE OPTIC NERVE
Chapter XIII.
ANATOMY.
The optic nerve collects its fibres from the retina, and passes from the
eye through the orbit into the brain. Three divisions of the nerve are
distinguished (Fig. 44) :
(1) Intra-ocular Division. Passing from the retina to the exterior ot
the eye, the nerve pierces the choroid and sclera at a spot a little to the
inner side of the posterior pole of the eye. This is the weakest part of the
eyeball, and is the first to give way when the intra-ocular pressure rises, as
in glaucoma. This opening in the sclera, through which the nerve passes,
forms a short canal called the " scleral canal," and is composed only of the
innermost layers of the sclera the lamina cribrosa which are perforated
by numerous small openings for the passage of the optic nerve fibres. The
choroid takes practically no part in the formation of this canal, ceasing
at the edge. The outer layers of the sclera are continued from the eyeball
on to the orbital part of the optic nerve, forming one of its sheaths. The
optic nerve, as it passes through the scleral canal, becomes very much
narrowed, owing to its fibres shedding their me<lullary sheath. (Plate TV.)
The part of the optic nerve in front of the lamina cribrosa is called the
head, and it is that which is seen by the ophthalmoscope. As already
stated, it lies at the same level as the rest of the fundus.
(2) Orbital Division of the Optic Nerve. This lies betAveen the eyeball
and the opening, or foramen, through which the nerve enters the skull on
its way to the brain. Its course is S-shaped, in order to admit of free
movements of the eyeball ; the retinal vessels enter this part of the
nerve, about half an inch behind the globe. The optic nerve consists of
many fibres half a million or more surrounded by three sheaths. The
bundle of fibres arising from the macular area is distributed in a definite
manner in the optic nerve. At the disc the fibres lie on the outer side, but
behind the globe thej^ quickly come to occupy a central pasition in the
nerve. This bundle is a large one, consisting of quite a quarter of the total
number of fibres.
(3) Intra-cranial part of the Optic Nerve. This is very short, and
extends as far as the optic chiasma, where the two optic nerves join
together, the inner fibres of each crossing over to join the fibres of the other
side. Each nerve, now called the optic tract, thus contains fibres from both
THE OPTIC NERVE. 139
retinae, and they are continued up to the various centres in the brain,
including those which control the pupil and accommodation. As the fibres
from the inner half of the retina cross over to the other side at the chiasma,
a lesion (an interruption in the conduction of the impulse by the nerve)
before the crossing -will cause blindness of that eye only, whilst a lesion, say,
of the right optic tract, Avill cause loss of sensibility in the outer half of the
right retina, and also in the nasal half of the left, and so both left visual
fields will be absent. This is called homonymous hemiopia, and indicates a
lesion of the optic tract. A lesion in the centre of the chiasma would cause
a loss of sensibility of the nasal halves of both retinae, and so the temporal
field of vision in both eyes would be lost. This is called "temporal hemiopia."
CONGENITAL ABNORMALITIES.
Colohoma of the Optic Nerve. This is a rare affection, and is due to
non-closure of the posterior portion of the foetal cleft. Either a deep
depression is found in the lower part of the disc, or the entire optic nerve
entrance is enlarged to several times its usual size, the vessels appearing to
be forced apart (Fig. 61). The nerve fibres are either aggregated around
the margin, or they may be placed in the upper portion of the papilla.
Coioboma of the optic disc.
DISEASES.
Inflammation of the Optic Nerve, or Optic Neuritis. Three kinds are
commonly described :
(1) Neuro-retinitis, in which the inflammation affects the head of the
nerve and the adjacent parts of the retina.
I40 THE OPTIC NERVE.
(2) Retro-bulbar neuritis, in which the disc is not inflamed, and so
appears normal ophthahnoscopically, but the macular bundle of nerve fibres
in the orbit behind the eye is affected.
(3) Papillitis, or choked disc, which is really not an inflammation ; the
disc appearing swollen owing to interference with its lymphatic circulation.
Neuro-retinitis. This inflammation affects the head of the optic nerve
(disc), and extends some short distance along the trunk, involving also the
contiguous portion of the retina. It is most frequently caused by ancemia,
syphilis, and chronic Bright's disease. Vision is often unaffected in the early
stages, but later it is diminished, thus recognition at first is only possible by
ophthalmoscopic examination, which reveals an indistinctness of the margins
of the disc, the latter appearing much larger than usual, owing to the
exudation extending on to the adjacent retina. The veins are engorged
and tortuous, whilst the arteries are generally smaller. The most important
sign is the swelling of the disc, as evidenced by parallactic displacement.
When the vessels on the disc are fixed, those on the fundus appear to move
quickly with the observer's head, as they lie at a lower level, or if the
vessels on the fundus be fixed, those on the papilla appear to move in the
opposite direction to the observer's head. The disc can also be distinctly seen
by a higher convex, or lower concave, lens than the rest of the fundus. The
colour of the disc is altered, being often mottled with white spots (exudate)
and red ones (haemorrhage). Various haemorrhages and exudates are also
seen in the surrounding retina.
This affection runs a very chronic course, often taking months for the
inflammatory symptoms to subside. In severe cases the disc gradually gets
paler as the swelling subsides, the margins become well defined, the eye
becoming more or less blind, but in milder cases the disc may return
to a more or less normal state, though vision is always slightly reduced.
Betro-hulhar Neuritis. In this no ophthalmoscopic signs are visible, as
only the orbital division of the optic nerve is affected. It may be acute in
its onset and progress, ot it may be chronic. The acute form occurs most
commonly in women, and may affect only one eye. Central vision is
suddenly much diminished, whilst the peripheral remains more or less good.
The patient sees better in the evening. On examination of the field of
vision a central scotoma, either partial or complete, is found to exist,
whilst the peripheral field is normal. The media and fundus appear healthy.
This affection is most frequently due to nasal trouble, and the treatment
is directed towards detection and removal of the cause.
Chronic Betro-hulhar Neuritis, or Toxic Amblyopia. The symptoms are
similar to the acute, but its onset is slower and more insidious, and it
always affects both eyes. The patient complains of an increasing difficulty
in reading, which he generally puts doAvn to age, and he states that vision is
better in the evening. Occasionally difficulty in recognising colour is
noticed. No improvement in vision, or only slight, is obtained by lenses.
THE OPTIC NERVE. 141
The media are clear, and ophthalmoscopic examination reveals very few, if
any, changes. In recent cases the disc^ may appear a little redder than
usual, or late in the disease some pallor of the temporal half of the disc
may be detected.
Examination of the field of vision reveals a central scotoma, confined at
first to colour, but later including form. Green is the first to disappear,
and then red. The peripheral field remains normal. The peripheral field
can be roughly tested by the hand, whilst to test the central field a small
piece of pink blotting paper on the point of a pen is held in front of the
examiner's nose. The patient looks at it with one eye, the other being
<;losd. The patient is unable to recognise the colour whilst looking directly
at the blotting paper, hut if he continues looking at the nose, whilst the
paper is moved gradually away, the colour will be recognised.
The commonest cause of toxic amblyopia is excessive tobacco smoking,
especially strong tobacco, as shag, and the abuse of spirituous beverages
favours its development. Other poisons, such as lead and arsenic, occa-
sionally give rise to this condition.
The treatment consists in abstinence from tobacco and alcohol, iodide of
potassium being given internally. If the scotoma has not become absolute,
the condition generally gets better in about a couple of months, but where a
total central scotoma is present, a complete cure is very improbable.
Choked Disc, or Papillitis. This is not an affection of itself, but only a
sign of an increased pressure within the skull. Usually no eye symptoms
are prevsent, but the patient frequently complains of severe headaches, and
occasional attacks of vomiting and giddiness, though sometimes slight
headaches are all that annoy him. Vision is good, provided no error of
refraction be present, and, if so, its correction w^ll improve the sight.
Tliis condition can only be recognised ophthalmoscopically when the
following picture is seen. The edges of the disc are fairly well defined, but
the vessels are engorged, and the disc is much swollen, the surrounding
retina being more or less normal. The absence of haemorrhages and exudates,
and the fairly well defined disc, distinguish it from optic neuritis.
Choked disc is not an inflammatory condition, but arises owing to an
increased pressure within the skull, the latter often being caused by a
brain tumor or cyst. This increased pressure prevents the return of the
lymph which lies between the sheaths of the optic nerve, so resulting in a
swelling of the head of the nerve the most important sign in the diagnosis.
The treatment is that of a brain tumor.
Optic Atrophy. This may develop gradually, without any previous
inflammation of the optic nerve (primary atrophy), or it may be the sequel
of an antecedent inflammatory condition (secondary atrophy). These two
42
THE OPTIC NERVE.
affections can be differentiated oplithalnioscopically. In optic atrophy the
visual acuity is much lowered, and the field of vision is contracted. Colour
blindness sets in early, red being lost first, then green, and lastly blue,
whilst in chronic glaucoma, which in the early stages might be confused with
atrophy, colour blindness does not occur until late in the disease. The pupils
are generally dilated, and more or less inactive. In optic atrophy due to
spinal lesions the pupil is frequently contracted, and, though inactive to
light, it readily reacts to accommodation (Argyle Robertson's pupil). The
media are clear, and the diagnosis is made from the ophthalmoscopic
appearance, which is as follows in the two states:
Primary optic atrophy.
Edg^e of disc is clear and well defined.
The vessels are smaller than normal.
There is slight, saucer like, cupping of
the disc, extending to its margins.
The disc is white, and the greyish mark-
ings of the lamina cribrosa are well
Secondary optic atrophy.
Edge of disc is irregular, owing to pre-
vious inflammatory conditions.
The vessels are smaller or of normal size,
but they have a white streak around
them.
The disc is rarely cupped, occasionally it
is slightly raised when the inflam-
matory products have not been com-
pletely absorbed.
The disc is white or bluish white, and the
lamina cribrosa is not seen.
The outlook in atrophy of the optic nerve is bad, the patient generally
becoming blind, nor does treatment influence it, unless the causal lesion can
be attacked with success.
U3
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Date.
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144
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Remarks
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Date.
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146
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Date.
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Name.
Date.
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Navie .
Date.
Remarks
10
Name.
Date.
Remarks
148
Natne.
Date.
Remarks-
12
Name.
Date.
Remarks-
13
149
Name.
Date.
Remarks
14
Name.
Date.
Remarks
so
16
Name.
Date.
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16
Name.
Date.
Retnark^
17
15'
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18
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152
19
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LIST OF BOOKS
For further study upon Special Subjects.
i^i
OCULAR
HISTOLOGY
s. d.
Histology of the Eye C. F. Pollack - - 15
Microscopic Examination of the Eye /". Greeff 5
OCULAR
MUSCLES
Muscular Anomalies of the Eye HaHsell& Keber 3 6
Refraction and Motility of the Eye IT. .V. Suter 8 4
Sight Z^ Cotiie -------50
The Ocular Muscles E. E. Maddox - - 6 3
OPHTHALMOSCOPY Atlas of Ophthalmoscopy- O. i/aaA - - 13
Manual oi Ophthalmoscopy y. E. Jennings - 7 6
Pocket Atlas and Text Book of the Fundus Oculi
Z. Johnson ------- 10 6
PHYSIOLOGIC Ophthalmic Optics-y. /Z Parsons
OPTICS Physiologic Opt\csM. Tscherning
6 6
10 5
PHYSIOLOGY OF
VISION
Curiosities of Light and Sight 5. Bidivell - 2 6
Text Book of Physiology (Part \\\)M. Foster 10 6
RETINOSCOPY Retinoscopy y. Thorington
The Keystone Manual of Retinoscopy
4 6
4 2
SIGHT TESTING
The Key to Sight Testing (2nd Edition)
Taylor & Mackinney - - - - 10 6
Refraction and How to Refract Thorington - 7 6
The above may he obtained from
J. & H. TAYLOR, Dioptric Works, Albion St., BIRMINGHAM.
J. & H. T.\YLOR (LoND.) Ltd., ;, Kirby St., Hatton Garden, LONDON.
INDEX TO PLATES
Plai K I. Trachoma and Paiiiuis PAt;!-:
Follicular Conjunctivitis
Phlyctenular Conjunctivitis
Ang-ular Conjunctivitis ... ... ... .. 4t>
Pl.ate II. Conjunctivitis
Ciliary Injection in Chronic Iritis
Chronic Iritis
Acute Iritis ... .. ... ... ... .S4
Platk III. Anterior Polar Opacity (focal illumination)
Anterior Polar Opacity (transmitted light)
Lamellar Cataract ... ... ... ... VM)
Platf. IV. Section of Normal Papilla (1)
Section of Normal Papilla (2)
Section of Atrophic Papilla
Section of Glaucomatous Papilla ... ... ... 108
Platk V. Normal Papilla seen Ophthalmoscopically
Glaucomatous Papilla n
Atrophic Papilla .- 10i>
Plate VI. Disseminated Choroiditis
Disseminated Choroiditis (advanced)
Rupture of Choroid ... ... ... ... ... Ht;
Plate VII. Normal Fundus of Fair Man
Normal Fundus -'
Myopic Fundus (1)
Myopic Fundus (advanced) ... ... .. 130
Plate VIII. Fundus in Retinitis Pigmentosa
Fundus in Retinitis Pigmentosa (advanced;
Fundus in Albuminuric Retinitis ... ... ... 134
Plate IX. Fundus of Shallow Detachment of Retina
Fundus of Detached Retina
Fundus of Embolism of Central Artery
Fundus of Opaque Nerve Fibres ... ... ... 136
Several of the aho7'e plates are reproduced by kind permission of the Publishers
of Haab's Atlas.
I NDEX.
'57
Abrasions of cornea
Albinism
Albuminuric retinitis
Amblyopia
Anatomy of conjunctiva
I choroid
cornea
iris ..
lens
lids
I retina
sclerotic ..
1 vitreous
Aniridia
Aniscoria ...
Antiseptics
Aphakia
Applantio cornea?
Aqueous humor
Arcus senilis
Argyll- Robertson pupil
Arterial pulsation
Arteries, anterior ciliary
Artery
Atrophy of optic disc ..
Atropine
Bacilli
Blennorrhoea
Blepharitis
Blepharospasm
Blood
corpuscles
Blows inflicted on cornea
Bowman's membrane ...
Brain
81.
63
114
134
183
43
113
5o
71
91
35
119
67
102
81
82
23
93
64
74
56
142
109
76
5
141
22
45
38
42
3
4
63
5t)
14
PAGE
Brig-ht's disease ... ... 140
Buphthalmos ... ... ... 112
Burns 63
Canaliculi ... ... ... ... 52
Canthi 37
Capsule of lens ... 91
Capsular cataract ... ... 95
Cataract 94
! anterior capsular ... 95
t cortical .. 95
II diagnosis of ... ... 95
lamellar ... ... 97
II Morg-agfnian 98
M perinuclear 97
n posterior polar ... 9(>
II progressive ... ... 97
.senile 98
traumatic .. ... 99
Cataracta fusiform is 9(>
I punctata ... ... 96
Catarrhal conjunctivitis 44, 46
Chalazion of eyelids ... ... 4<J
Choked disc ... ... .. 141
Choroid, anatomy of 113
I' coloboma of ... ... 114
detachment of ... 117
II hajmorrhage in ... 117
II rupture of ... ... 117
II tumour of 117
Choroiditis ... .. 114
senile . ... 116
myopic 116
Ciliary arteries ... ... 76
body 71, 8H
Cocaine .. ... 78
Coloboma of iris ... 81, 90
58
INDEX
Colobomji of lens
I. optic nerve
Conical cornea ...
Conjunctiva, anatomy of
11 diseases of
Conjunctivitis, ans<-ular ...
I eczematosa
Connective tissue
Corectopia
Coredialysis
Cornea, abrasions of ...
jinatomy of
11 conical ...
II foreiiifn substance in
<i inflammation of
<< injuries of
'I opacities of ...
pannus
II ulcers of
Crick dots
Crystalline lens, anatomy of
II II diseases of
Cuppinjjf of disc ... 1
Cyclitis
Cv.st
D
Deg-eneration
1. of choroid
Dendritic ulcers ...
Descemels membrane ...
Detachment of choroid
II retina ...
Development of lens
Diabetes
Diabetic cataract
Diplobacillus
Direct ophthalmoscopic exam
Discoria
Dislocation of lens
Distichiasis
Duct, lachrvmal
lAUK
93
E
H.\i;
189
Ecchymosis
35
}.->
Eictasia of cornea
65
43
ti sclera
69
44
Ectopia lentis
93
4.)
Ectropion
42
47
Elong-ation of myopic eyeball
70
2
Embolism of central arterv
135
S2
Entropion ...
41
88
Epiphora 42, 53
(>3
Epithelial ti.ssue ...
2
55
Episcleritis
68
(Jo
Eserine ... ...-
78
48
Eversion of lids ...
49
57
Examination of the eye
26
(J3
Exophthalmic g-oitre
129
63
Eyeball, tension of
107
>1
58
Eyelashes, eversion of ..
42
62
<i inversion of
41
132
Eyelids, anatomy of
35
91
.1 eversion of
49
..
94
t. inflammation of
39
08,
129
It inversion of
49
49
87
40
F
117
62
56
117
136
92
134
100
45
30
82
101
41
53
Field of vision
Focal illumination
Follicular conjunctivitis
Fontana, spaces of
ForeisJ^n bodies on corne;
Fovea centralis
Fundus
Gland, lachrymal
Glaucoma ...
Glioma of retina
Granular lids
H
Hairs
Hemeralopia
Hemiopia ...
.. 125
.. 26
47
73
48, 63
.. 119
.. 126
52
107
137
46
... 39
... 133
8(1. 139
INDKX.
PAGE
Honiatropiiu'
78
Hordeolum
... 39
HorfH*r"s muscle ...
... 58
Hutchinson's teeth
.")!>
Hyaloid artery
i(i;i, 1-27
H\ P'-T.-LMiiia of iris
... s:i
lids
3S
Hyperafsthesia of retina
... 133
Hypha?ma
... ss
Hypopyon
HI, 83
I
Indirect ophthalmoscopic exam
Inflammation
lujuries of choroid
ciliary body
., cornea
., crystalline lens
iris ...
Intra-ocular pressure
Iridectomy
Irido-cyclitis
Irido-dialysis
Irido-donesis
Iri^
Iritis
anatomy of ...
bom be
coloboma of
detachment of
injuries of ...
prolapsi- of ...
tremulous
iridectoniN- in
Keral ectasia
Keratitis
interstitial
parenchymatou.'
punctata
1 .syphilitic
ulcerative
2<)
2(1
. 117
S8
)3
S)9
. 88
. no
85
88
88
81
71
. 8o
81, 90
89
88
89
81
45, 83
8.")
it)
45, 57
59
59
57, 87
59
58. ()<
Keratoconus
Keratoj^lobus
PAGK
65
Lachrymal apparatus ...
II inland
II sac
Lachrymation
Lag-ophthalmus ...
Lamina fu.sca
Lens, cry.stalline, anatomy of ...
n ti development of
II ti diseases of ...
11 II dislocation of
II suspensory
lig-ament of ...
Lenticonus
Leucoma ...
Levator palpebral
Lids, anatomy of
diseases of
Liji^-amentum pectinatum 73,
Lipoma
Luxation of Lens
Lymph
Lymphatics
Lvnchisis ...
M
Macula lutea
Meibomian c}st ...
II g-lands
Membrane of Bruch
Microbes ..
Morg-ag-nian cataract
Muller's muscle ...
Musca? volitantes
Mu.scle, Horner's
II of iris
Muller's ...
i. orbicularis
Musculai" tissue ...
119,
52
52
53
52
42
113
91
92
94
101
91
93
63
3(>
35
38
110
48
101
1(>4
I3(>
40
36
113
21
98
36
1(>4
53
72
36
36
i6o
PACK
Mydriasis 79, 9(J
Mydriatics 78
M3'Oj5ia, causes of ... ... 7()
posterior staphyloma in 116
Myopic crescent ... ... 116
Myosis m
Myotics 78
N
Nasal duct 52
Nebulae of cornea ... ... 63
Nerve cells .. 13
fibres 13
II ;i opaque ... ... 132
optic 138
Nervous tissue ... ... ... 12
Neuro-retinitis .. ... ... 140
Nigrht blindne.ss 133
Nucleus ... .. ... ... 2
Nyctalopia 133
Nystagrnus ... ... .. 114
Occlusio pupilla; ... ... .. 84
Opacities in choroid ... ... So
11 of cornea ... ... 03
II crystalline lens ... 94
II vitreous ... ... 104
Opaque nerve fibres ... ... 132
Ophthalmoscopic examination 29
Ophthalmoscopic examination
direct method ... ... 30
Ophthalmoscopic examination
Opi
indirect method
.. 31
tic atrophy
... 141
II chiasma
... 138
11 disc
120, 126
.1 neuritis
... 139
II nerve, anatom\
of
... 188
.1 11 atrophy
of
... 141
1 V. di.seases
of
. 139
4. 1, excavation of
... 142
Optic papilla
II tracts
Orbicularis muscU
paralysis
spasm of
36,
PAGK
139
79
43
42
Pannus ... ... ... 51, 58
I'alpebral conjunctiva ... 36, 43
M muscles ... ... 42
Papillitis 141
Patholot^y 20
Po.sterior staphyloma ... ... 116
11 .synechise .. ... 84
Phlyctenular conjunctivitis ... 47
Pilocarpine ... ... ... 79
Pinj^uecula ... ... ... 47
Pink eye ... ... ... ... 45
Pteryg-ium ... ... ... 47
Physiolog-ical cupping; .. ... 109
Ptosis 43
Pulsation 128
Pul.se 6
Punctum lachrymale .. 37, 44, 52
Pupil 71
Pupillary actions 79
displacement ... 82
n membrane ... ... 82
R
Reflex action ... ... 16, 77
Retina, anatomy of ... ... 119
11 detachment of... ... 136
11 embolism of ves.sels of 135
Retinitis . 134
II albuminuric ... .... 134
11 hoemorrhagfica .. 135
II pig-mentosa ... .. 135
Retinoscopy ... ... ... 26
Retro-bulbar neuritis ... .. 140
Riggf's disease ... ... ... 86
Rodent ulcer ... ... ... 62
INDHX.
iTm
Rods and cones ...
Rupture of choroid
Rupture of iris ...
T
Tarsus
Tears
Tendo oouli
Tension of eyeball
Toxic ainblxopia
Toxins
Trachoma ...
Tr.-msniitted li_nht
HAUK
121
117
89
Sohlemm's canal
73
Scleritis
()H
Sclerotic ...
67
.Scotoma
1-2.-)
Seclusio pupilUe ..
.. S4, 89,
Ill
Secondary cataract
100
Shot silk retina ...
181
Sphincter pupilla;
7
Staphyloma of cornea .
m
, m
11 of sclera
n9
II posterior
116
Stye
89
Subluxation oi' lens
100'
Svnchisis scintillans
104
Synechia, posterior
84
Syphylitic keratitis
.)9
36
53
8<)
107
140
22
4H
i'6
Traumatic (\itaract
Trichiasis
Tiunour
Tumours of choroid
u
Ulceration
Ulcers of cornea
Ulcus serpens
Uveal tract
V
i'A(;k
.. 99
41
2.-), 48
.. 117
24
(>2
62
113
\'ascular pulsation
Vein
Veins, anterior ciliary, ...
Venae vorticosa^i
\'isual sensations
\"itreous humor ...
II II . anatomy of
II II inflammatiot
II ., liquefaction
II II opacities of
Yellow spot
iof
of
128
.")
76
76
124
102
102
m
104
104
119, 180
Zonular opacity of cornea
Zonule of Zinn ... ... 74,
91,
tio
102
I 62
THE FOLLOWING ARTICLES MAY BE OBTAINED FROM
J. & H. TAYLOR, Dioptric Works, Albion St., Birmingham.
J. & H. TAYLOR (Lend.) Ltd., 33, Kirby St., Hatton Garden,
London.
TRIAL CASES
Polislicd inaho.naiiy case, hii^hh' tlnishccl with bevollod plate tjlass top, removable
lid, trav for lenses to lift out, i^ood fittint<-s and lock, all lenses in fine test rins<-s
with pierced handles ... ..' ... ... ... 8
Without trial frames ... 7/6 less.
CONTEXTS
30 pjiirs spherical c/x "25 to 20D
30 M n C/C '2-:, to 20D
18 single c\iinders c/x -2^ to 7D
18 ., ' c/c -25 to 7D
12 prisms
1 each phmo 'ruh\-, amber, tureen
and white
4 discs
1 single cell trial frame
1 dovible cell iii^iduated trial fr.'ime
12 blue and smoki.' Li'lasses
Polished mahog-any case, his^hly finished, with bevelled plate iilass top, removable
lid, tray for lenses to lift out, ifood fittinsjfs and lock ... ... 9 16
Without trial frames ' ... 7/6 le.ss.
CONTENTS :
T^2 pairs .spherical
S2 n
18 pairs cvlinders
18 r "
c/x -25 to 20D
c/c 2-:, to 20D
c/x 25 to 7D
c/c -25 to 7D
12 prisms 1 A to 12*
12 piano blue and smoke i^-lasses
I each piano red, amber, screen, and
white
5 discs
1 chromatic test
1 Maddox rod
I sintjle cell trial frame
1 double cell S4fraduated trial frame
1 63
TRIAL CASES-Co,>/inn,rL
Leather covered, finely finished case, with velvet and leather fittinjirs, all lenses
mounted in tempered nickel plated spun rims ... ... 9
Without trial frames ... 7/6 less.
CONTEXTS:
3 J pairs spherical c/x -12 to 2oD j 3 coloured g-lasses
32 1. c/c '12 to 20D I I Maddox rod
20 pairs cvlinders c/x '12 to 6D | 6 stenopaic and occluding- discs
20 .- ' " c/c -12 to 6D I 1 double cell g-raduated trial frame
ID prisms i^ to 10^ I 1 sing-le cell trial frame
Or with best standard trial frame, adjustable sides
10
Contents same as above, but fitted in solid oak case, with plate .glass te^p and
drawer beneath, lenses fitted in removable tra\ ... 10 10
Roll top fumed oak cabinet trial case, removable tray, best work tiiroughout.
two drawers
10 12
CONTKNTS :
35 pairs .spherical
35 ."
21 i> cylinders
21 tt ,.
15 prism
c/x '12 to 20D
c/c '12 to 20D
c/x -12 to 6D
c/c '12 to 6D
I to 20
14 discs and coloured g-Jasses
No trial frames are includeil.
liifocal trial set, in black seal gfiain leather covered case. Ringfs 38mms. Reading
segments are cemented on to piano distance, and may be had of any shape
preferred bv the optician. There are 12 pairs of lenses, from -f '^o to -r3'.25
-spherical " ... ^ 1 15
64
TRIAL FRAMES, CHARTS, &C.
m^Mf^
Patented double cell, extension temples, celluloid scales on eyes and bar, 17 6
Three-cell, same as above, but patented revolviny;- cell and thumb screw, best^
make : 1 15
Do.
do.
id qualit\-
1 12
Snellen's test type, various letters and arran^-ements, black letters on white card,
per card ... ... ... ... ... ... ... 10
Ditto, cards with metal edg-e to top ... ... ... per card 1
Per set of four
Snellen's test type, reversed, for use with mirror ... per card
Test type, white letters on black g-round
Snellen's reading- type, 8 X 5>^in., distances in feet
Jaeg-er's test type, folding- 14 x iiin., distances in centimetres
Lionel Laurance chart Ordinary type, 40 x 25in.
Reversed type
Portable chart, 18 J^ x i2^2'ii'
Two extra cards for changing type
4
-d 1
1
3
6
9
9
6
.. 10
6
7
6
2
i65
CHARTS AND ACCESSORIES.
If tT F
"'" O B
^Ns mN ,jnv
s-S^-i
Asti^malif fan, lari^-e si/.o paper
AstijJ-matic tan, linen, mounted on rollers
Astijjfmatic clock face (as illustrated) i.S x iS"
Test type (after Dr. Pray) for Astig-matisni,
circles
Test type (after Dr. Pray) for Astigmatism,
letters (as illustrated) ...
Pinhole disc, black bronzed metal, in
nickelled steel frame, with ebony handle
Stenopaic slit, mounted as above
Stenopaic slit, adjustable for various widths
Revolving- slits and pinholes of various sizes,
with spring- clip and jjfroove for holdinjf
lens ...
Disc or lens holder, nickelled steel, ebony
handle
Test rinjc, with vivid blue, i^reen, or opaque
i^-lass
Maddox rod, white or red, for testing: mus-
cular insufficiency (as illustrated)
Maddox triple rod, white or red, for testinj^
muscular insufficiency
Maddox multiple jjfroove, white or reil
Maddox prism, moiuited in test rinif
Jackson's cros.sed cylinder in nickelled rinif,
with handle
Near point measure, boxwood
Test cards for near point measure
Retinoscope, plain or concave mirror, with
ebony handle
Thorinijton's retinoscope (as illustrated) ...
6
2
2
3
6
6
1
1
2
6
2
9
4
4
2
6
5
6
2
6
4
6
[66
CHARTS AND ACCESSORIES
Chambers' Inskeep practice eye for retinoscopy, with
slidini*- brass tube, and concave fundus with i^-ood
retinal picture ... ... ... ... ... 050
The "Hu-Model" practice eye for Retinoscopy and Ophthal-
moscopy. The ordinary refractive conditions of the
human eye are represented by the use of 5 solid g-lass
models, which are inserted into a metal tube with iris
diaphragm. In morocco case ... ... ... 150
The "Hu-Model" selection of fundi, to be used with above,
the various diseases beings reproduced from Haab's
Atlas. In case ... ... 18/- the set, or 16- each.
Asbestos retinoscopic chimney ... ... ... 026
Asbestos retinoscopic chimney, with iris diaphrag"m ... 8
Mackinney's ophthalmic bracket, with electric or g-as
fitting-s. This is very simple in construction, and is
self-fixing- in position by merely releasing the handle
which is attached to an eccentric cam. The bars are
telescopic, and the whole is highly finished in dead
black (chimney is extra) ... ... 1126
67
CHARTS AND ACCESSORIES.
ANALYZING
FOR ANALYZING
AND
CENTRING
LENSES
Morton's ophthalmoscope, best Enghsh make
Manifold prescription books of loo pa^es
Dalziel's chart, for analyzing and centerinjj- lenses (as
illustrated)
Mackinney's prism chart, for testing^ the prismatic power
of a lens in deg^rees of refracting- angle, degrees of
deviation, and prism dioptres. Also useful for testing
muscular balance at a near distance
COMBINED PRISM SCALE.
i i H . iHi i i i i . j i j i i i iiiiiii i h^
a 1 I I * I *
I 1 I I' l ' ^ ' l I t'l I ' l
i'l ! 'l' !'l - '
hl i ih |. hiMi i i i i. i |M| ,i iii i. h i | ii.|i i . rM| .i i i iHi
t^
each.
s. d.
2 4
16
3 6
2
1 68
Codding-ton magnifier, nickelled mount,
with cover and rinj^-, lin. diam., for
examine the cornea
The Converg-iscope is a binocular mag-ni-
fier which is affixed to the head by a
' band, giving a stereoscopic effect to
the object examined, with ease and
comfort to both eyes. The lenses are
fitted to a lig-ht straw hood
Condensing lens, diam. 2)4in. ; 2%'^.
or 3in. focus
Condensing lens, diam. 2}^\x\. ; in strong-
nickel mounts
Reid's test type (readings) on stout folding"
cardboard, covered leatherette and var-
nished, with music and time tables
Mahogany frame, open back and front,
9x6in., containing- test type for reading,
with time table on reverse
Oak frame, as above, closed back
\^ M with handle (illustrated)
H II open front and back ...
Prescription books of lOo pag"es ... each
Record books of loo pages ... m
THE "NEW" KERATOMETER. This instrument i.s of Briti.sh
manufacture, and while embodying- the simple form of construction found in the
older types, is practically a one-position model, with all the advantagfes of this
class of instrument, but with its previovis errors eliminated. A booklet de-scribing-
its construction and use will be forwarded on application.
Price, fitted for electric light ... 10 10
169
ADJUSTABLE INSTRUMENT TABLE. This is heavily
built of iron, and can be raised or lowered by simply revolvinj^-
the wheel. The top is of fumed solid oak, the stand being
copper plated and bronze finished.
Price
Adjustable stool
2 4
1 17
Packing and case extra.
70
luniiiiating bracket, strongly
made, of nickel plated
brass tube, with parabolic
reflector and cover, with
iris diaphragm. 'I'he
cover is hinged to the
hood and can be swung
behind, giving the full
illumination of Reflector.
An iris diaphragm, gradu-
ated in millimetres, is
fitted, and three yards
of wire with adapter is
supplied ... 1
1
A similar device
to above, with
iris diaphragm,
&c., and double
ball joint (the
reflector only
being shown).
110
i
1
14 DAY USE ^
RFTURN TO DESK FROM WHICH BORROWED WT
^>"TOMETRY LIBnARY J
This book is due on the last date stamped below, or ^g
on the date to which renewed. |W|^
Renewed books are subject to immediate recall. HT
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LD 21-507n-4,'63
(D6471sl0)476
General Library
University of California
Berkeley
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U C BERKELEY LIBRARIES
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