IT 
 
 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
THE OPHTHALMOSCOPE 
 
 AND 
 
 HOW TO USE IT 
 
 THORINGTON 
 
BY THE SAME AUTHOR 
 
 Refraction and How to Refract 
 
 Third Edition. With 215 Illustrations, many of 
 which are from original drawings, seven being colored. 
 
 Cloth, net, $J.50. 
 
 From. The New York Medical Record: 
 
 "Can be recommended not only to beginners in the study 
 of ophthalmology, but to those practitioners and students as 
 well whose limited knowledge of mathematics precludes the 
 study of Helmholtz or Donders. ' ' 
 
 Retinoscopy (The Shadow Test) 
 
 In the Determination of Refraction at One Meter 
 Distance with the Plane Mirror. 
 
 Fourth Edition. 51 Illustrations, a number of 
 which are in colors. Cloth, net, $J.OO. 
 
THE OPHTHALMOSCOPE 
 
 AND 
 
 HOW TO USE IT 
 
 WITH COLORED ILLUSTRATIONS, DESCRIPTIONS, AND 
 
 TREATMENT OF THE PRINCIPAL DISEASES 
 
 OF THE FUNDUS 
 
 JAMES THORINGTON, A.M., M.D. 
 
 AUTHOR OF "REFRACTION AND HOW TO REFRACT" (THIRD EDITION) AND "RETINOS- 
 COPY" (FOURTH EDITION); PROFESSOR OF DISEASES OF THE EYE IN THE PHILA- 
 DELPHIA POLYCLINIC AND COLLEGE FOR GRADUATES IN MEDICINE; MEMBER 
 OF THE AMERICAN OPHTHALMOLOGICAL SOCIETY; FELLOW OF 
 THE COLLEGE OP PHYSICIANS; ETC. 
 
 73 illustrations 12 Colored plates 
 
 PHILADELPHIA 
 P. BLAKISTON'S SON & CO. 
 
 IOI2 WALNUT STREET 
 1906 
 
COPYRIGHT, 1906, BY P. BLAKISTON'S SON & Co. 
 
 PRESS OF 
 
 THE NEW ERA PRINTKG& 
 LAHCASTER. PA, 
 
PREFACE. 
 
 THIS book has been written for the student and 
 general practitioner who desires to obtain a work- 
 ing knowledge of the ophthalmoscope with the in- 
 terpretations of its findings, and has not the time, 
 ordinarily, to study a large text-book on the dis- 
 eases of the eye, in which the subject is too deeply 
 embedded for immediate comprehension. 
 
 While it is admitted by every intelligent practi- 
 tioner that the ophthalmoscope for the detection 
 of many diseases is frequently a necessity, yet to 
 be able to use the instrument does not mean that 
 the observer must be an expert ophthalmologist. 
 
 With the ophthalmoscope, the examiner may 
 see conditions pictured which signify disease of the 
 brain, spinal cord, heart, kidney, blood, blood- 
 vessels, etc., that he might not detect in any other 
 way, thus making a diagnosis with certainty and 
 satisfaction. 
 
 In the preparation of the manuscript and the 
 arrangement of these pages and chapters, the 
 writer has planned to be systematic and practical, 
 so that starting with the consideration of the oph- 
 thalmoscope and its optic principles as also the 
 optic principles and anatomy of the eye, the reader 
 is brought to a knowledge of the normal eye and 
 
VI PREFACE. 
 
 has a colored sketch presented of a healthy eye 
 ground as a guide for comparative descriptions. 
 Finally the reader is given a comparison of the 
 normal with the pathologic, so that when he sees 
 a certain condition in the eye ground, he will know 
 at once whether the appearance indicates health, 
 or an anomaly or disease, and the structure or 
 structures involved. However, to enhance the 
 value of the work, the writer has selected for his 
 descriptions and illustrations those diseases of the 
 eye ground which appeal to the general practitioner 
 in every-day practice. The sketches in color were 
 made by a noted artist and under the writer's per- 
 sonal supervision, from individual patients in his 
 own practice. These sketches, made by the aid of 
 artificial light, should be studied under similar con- 
 ditions (see page in). 
 
 The subject of prognosis and treatment of the 
 various diseases described has not been exhausted, 
 but has been sufficiently touched upon to give the 
 reader a proper understanding of the subject with- 
 out making a work of this character unnecessarily 
 large. 
 
 120 S. EIGHTEENTH ST., PHILADELPHIA, PA. 
 January, 1906. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 THE OPHTHALMOSCOPE. CHOICE OF AN OPH- 
 THALMOSCOPE. VARIETIES. ILLUMINATION. - 
 THE MIRROR. MYDRIATICS. OBSERVER. PA- 
 TIENT. HOW TO USE THE OPHTHALMOSCOPE. 
 DIRECT AND INDIRECT METHODS. OBLIQUE IL- 
 LUMINATION i 
 
 CHAPTER II. 
 
 OPTICS. LIGHT. REFLECTION. R EFRACTION. 
 LENSES. HYPERMETROPIA. MYOPIA. ASTIGMA- 
 TISM. ESTIMATING THE REFRACTION BY THE 
 DIRECT AND INDIRECT METHODS AND RETINO- 
 SCOPY 44 
 
 CHAPTER III. 
 
 ANATOMY AND ANOMALIES OF THE EYE. 79 
 
 CHAPTER IV. 
 
 THE NORMAL EYE GROUND 108 
 
 CHAPTER V. 
 
 STRUCTURAL ALTERATIONS OR CHANGES IN THE 
 CORNEA, AQUEOUS HUMOR, IRIS, LENS AND 
 VITREOUS HUMOR WHICH ARE INDICATIVE OF 
 DISEASE OR INJURY 128 
 
 vii 
 
Vlll CONTENTS. 
 
 CHAPTER VI. 
 
 VISUAL ACUITY. FIELD OF VISION. PERIMETRY. .. 140 
 
 CHAPTER VII. 
 
 RETINAL VESSELS. HEMORRHAGES. PIGMENT. 
 CHANGES. HYPEREMIA. ANEMIA. EMBOLISM. 
 THROMBOSIS 148 
 
 CHAPTER VIII. 
 
 DISEASES OF THE RETINA 176 
 
 CHAPTER IX. 
 
 DISEASES OF THE OPTIC NERVE 229 
 
 CHAPTER X. 
 
 DISEASES OF THE CHOROID. GLAUCOMA 259 
 
 INDEX 287 
 
LIST OF ILLUSTRATIONS. 
 
 PLATES 
 
 PACE. 
 
 I. Normal Fundus To face 1 18 
 
 II. Embolism of the Central Artery " 164 
 
 III. Thrombosis of the Central Vein (So- 
 
 called Hemorrhagic Retinitis) " 172 
 
 IV. Albuminuric Retinitis " 190 
 
 V. Albuminuric Retinitis of Pregnancy.... " 198 
 
 VI. Retinitis Diabetica " 202 
 
 VII. Retinitis Pigmentosa " 208 
 
 VIII. Detachment of the Retina " 216 
 
 IX. Atrophy of the Optic Nerve (Post Pap- 
 illitic Atrophy) also Medullated Nerve- 
 fibers " 248 
 
 X. Primary Optic Atrophy " 252 
 
 XI. Retino-Choroiditis " 264 
 
 XII. Glaucoma " 278 
 
 TEXT FIGURES. 
 
 1. The Loring Ophthalmoscope 3 
 
 2. The Morton Ophthalmoscope 5 
 
 3 and 4. The DeZeng Luminous Ophthalmoscope... 7 
 
 5. The Student Lamp and Cover Chimney with Ad- 
 
 justable Bracket 10 
 
 6. Author's Iris Diaphragm Chimney n 
 
 7. Author's Schematic Eye 14 
 
 8. Correct Position for Direct Ophthalmoscopy 23 
 
 9. Correct Position for Holding the Ophthalmoscope. 24 
 
 ix 
 
X LIST OF ILLUSTRATIONS. 
 
 PAGE. 
 
 10. Very Faulty Position of Holding the Ophthalmo- 
 
 scope 25 
 
 11. Direct Ophthalmoscopy, Outlined in Hypermetropia 28 
 
 12. Direct Ophthalmoscopy, Outlined in Myopia 29 
 
 13. Position for Indirect Ophthalmoscopy 30 
 
 14. Author's Condensing Lens 31 
 
 15. Indirect Ophthalmoscopy, Outlined 33 
 
 1 6. Oblique or Focal Illumination 38 
 
 17. Oblique or Focal Illumination and Object Magni- 
 
 fied with Condensing Lens , 39 
 
 18. Loupe 40 
 
 19. Oblique or Focal Illumination with Object Magni- 
 
 fied with Loupe 41 
 
 20. Cover Chimney with Condensing Lens Attached. . . 42 
 
 21. Illustrating Intensity of Light 45 
 
 22. Parallel Rays Refracted by a Convex Lens Form- 
 
 ing a Convergent Pencil 46 
 
 23. Parallel Rays Reflected by a Concave Mirror Form- 
 
 ing a Convergent Pencil 46 
 
 24. Illustrating a Divergent Pencil 48 
 
 25. Reflection 50 
 
 26. Reflection from a Plane Mirror 51 
 
 27. Lateral Inversion 52 
 
 28. Reflection by a Concave Mirror 54 
 
 29. Erect Image Formed by a Concave Mirror 54 
 
 30. Inverted Image Formed by a Concave Mirror 55 
 
 31. Image Formed by a Convex Mirror 56 
 
 32. Perpendicular to Plane Surfaces 58 
 
 33. Refraction 58 
 
 34. Maximum Deviation 59 
 
 35. Minimum Deviation 59 
 
 36. 37, and 38. Convex Lenses 60 
 
 39, 40, and 41. Concave Lenses 61 
 
 42. Prism Formation of a Convex Lens 62 
 
 43. Prism Formation of a Concave Lens 62 
 
LIST OF ILLUSTRATIONS. XI 
 
 PAGE. 
 
 44. Parallel Rays Passing Through a Convex Lens. . . 63 
 
 45. Parallel Rays Passing Through a Concave Lens ... 63 
 
 46. Conjugate Foci 64 
 
 47. Negative Focus 65 
 
 48. Inverted Image Formed by a Convex Lens 65 
 
 49. Erect and Magnified Image Formed by a Convex 
 
 Lens 66 
 
 50. Image Formed by a Concave Lens 66 
 
 51 and 52. Convex and Concave Cylinder Lenses 68 
 
 53. Cylinder Axis 69 
 
 54. Parallel Rays Passing Through a Convex Cylinder. 69 
 
 55. Parallel Rays Passing Through a Concave Cylinder. 70 
 
 56. Hypermetropic Eye at Rest 70 
 
 57. Hypermetropic Eye Refracted 71 
 
 58. Emmetropia 71 
 
 59. Myopic Eye at Rest 71 
 
 60. Myopic Eye Refracted 72 
 
 61. Horizontal Section of the Right Eye 80 
 
 62. Varieties of Persistent Pupillary Membrane 101 
 
 63. Various Forms of Opacity of the Crystalline Lens. . 102 
 
 64. Head of the Optic Nerve no 
 
 65. To Determine the Position of a Fixed Opacity in 
 
 the Eye 138 
 
 66. Randall's Test Letters 140 
 
 67. Gould's Test Letters 141 
 
 68. Illiterate Card 142 
 
 69. McHardy's Perimeter 143 
 
 70. Field Charts 144 
 
 71. Form Field Showing Contraction in All Meridians. 212 
 
 72. Form Field in Partial Detachment of the Retina. . . 220 
 
 73. Depressions in Optic Disc 233 
 
THE OPHTHALMOSCOPE 
 
 AND 
 
 HOW TO USE IT 
 
 CHAPTER I. 
 
 THE OPHTHALMOSCOPE. CHOICE OF AN OPHTHALMOSCOPE. 
 VARIETIES. ILLUMINATION. THE MIRROR. MYDRIATICS. 
 OBSERVER. PATIENT. HOW TO USE THE OPHTHALMO- 
 SCOPE. DIRECT AND INDIRECT METHODS. OBLIQUE 
 ILLUMINATION. 
 
 Ophthalmoscope. From o<0aX/xos, " eye "; and 
 ayoTreiv, " to observe " or literally " to view an eye." 
 An instrument used for studying the media and 
 interior of an eye. 
 
 Choice of an Ophthalmoscope. As the purpose 
 of an ophthalmoscope is to permit the observer to 
 see clearly the interior of an eye, therefore in select- 
 ing an ophthalmoscope it is not at all necessary to 
 obtain the most expensive or most complicated in- 
 strument, but rather to select the one which will 
 answer the purpose for which it is intended. The 
 original ophthalmoscope of Helmholtz (1851) is 
 a crude affair and is now a museum curiosity, as 
 the ophthalmoscope of the present day excels the 
 
2 THE OPHTHALMOSCOPE. 
 
 Helmholtz instrument in every particular. There 
 is an infinite variety of ophthalmoscopes in the 
 market, but for the general student the modified 
 instrument of Loring appears to meet with most 
 favor in America, and the Morton, an excellent in- 
 strument, is quite popular abroad. 
 
 The Loring Ophthalmoscope (Fig. i). The 
 mirror of the Loring instrument is concave, with 
 a radius of curvature of 40 centimeters, giving 
 therefore a principal focus at 20 centimeters. The 
 sight-hole of this mirror is round and usually about 
 3^2 millimeters in diameter, cut through the glass. 
 As an improvement over such a mirror and to take 
 its place, the writer would recommend the mirror 
 used on his own ophthalmoscope which has a radius 
 of curvature of 15 centimeters and the sight-hole 
 2 millimeters in diameter, not cut through the glass, 
 but made by simply removing the quicksilver. The 
 glass left at the sight-hole gives additional reflect- 
 ing surface and at the same time does away with 
 annoying reflexes or aberrations which often oc- 
 cur when the glass is perforated. The small sight- 
 hole is an advantage also when looking through 
 small pupils. The mirror should be of thin glass 
 and the silvering of the very best quality. The 
 mirror can be tilted to an angle of 25 degrees, is 
 oblong in shape, 18 by 33 millimeters, and is se- 
 cured at the middle of its ends (Fig. i) by two 
 elevated screws to the cover on a revolving milled 
 wheel. This milled wheel or disk contains fifteen 
 
THE LORING OPHTHALMOSCOPE. 3 
 
 small spheric lenses, each 6 millimeters in diameter, 
 set in the form of a circle near its circumference. 
 The series of spheric lenses of different strength 
 range from I D. to 8 D. and from + i D. to 
 
 FRONT BACK 
 
 FIG. i. Loring Ophthalmoscope. 
 
 + 7 D. The central opening is left free, does not 
 contain a lens and is marked o. Each lens may be 
 turned in succession to the sight-hole by revolving 
 the milled wheel or disk with the end of the index 
 
4 THE OPHTHALMOSCOPE. 
 
 finger of the hand which holds the instrument ( Fig. 
 10). When it is necessary to use a lens stronger 
 than 8 D. or -f- 7 D., there is an additional quad- 
 rant ("back" view, Fig. i), which can be super- 
 imposed and turned into place at the sight-hole; 
 this quadrant contains four lenses, 0.50 D. and 
 16 D.; also + 0.50 D. and + 16 D. With this 
 quadrant and the spheres in the milled wheel any 
 combination or strength of lens from 0.50 D. to 
 -24 D. and +0.50 D. to +23 D. (a series of 
 sixty- four) may be placed at the sight-hole, as 
 shown by the following table. 
 
 Plus. Mill us. 
 
 I 
 
 1 2 
 
 2 3 
 
 3 4 
 
 4 5 
 
 5 6 
 
 6 7 
 
 7 8 
 Bring up + 16 Bring up 16 
 
 + i6C 8= 8 i6C + 7= 9 
 
 7=9 +6= 10 
 
 6=10 +5= ii 
 
 5 = ii +4= 12 
 
 4=12 +3= 13 
 
 3=i3 +2= 14 
 
 2=14 +1= 15 
 
 i = 15 +0= 16 
 
 0=16 i= 17 
 + 1 = 17 2= 18 
 + 2=18 3= 19 
 -(-3=19 4 = 20 
 + 4 = 20 5= 21 
 -(-5 = 21 6= 22 
 + 6 = 22 7 = 23 
 
THE MORTON OPHTHALMOSCOPE. 
 
 Plus. 
 
 Bring up -f- 0.50 
 
 C + i = 
 
 0.50 
 
 1-50 
 
 2.50 
 
 3-50 
 4-50 
 5-50 
 6.50 
 7-50 
 
 Bring up 0.50 
 
 Minus. 
 
 8 = 24 
 
 = 0.50 
 : 1 = 1.50 
 : 2 = 2.50 
 : 3 = 3-50 
 
 4 = 4.50 
 
 : s = 5-50 
 : 6=1 6.50 
 : 7 = 7-50 
 
 8 = 8.50 
 
 An index immediately beneath the sight-hole of 
 the instrument records the strength of lens in whole 
 numbers that is being used. In the Morton instru- 
 ment each lens is projected before the sight-hole 
 
 FIG. 2. Morton Ophthalmoscope. 
 
 through an endless groove and propelled by a driv- 
 ing wheel and cogs at the lower end of the instru- 
 ment (Fig. 2). In this Loring instrument the 
 
6 THE OPHTHALMOSCOPE. 
 
 minus lenses are numbered in red figures and the 
 plus lenses in white. The Morton uses the reverse 
 of these colors, i. e., white for the minus lenses and 
 red for the plus. When the 0.50 lens (plus or mi- 
 nus) is in position then its strength must be added 
 to or subtracted from the whole number at the 
 sight-hole. By the foregoing table it will be noted 
 that 8.50 and + 7.50 are the highest half-num- 
 bers that can be obtained or are ever necessary for 
 any purpose. The handle of either ophthalmoscope 
 is made partly of brass and partly of bone; this 
 latter can be unscrewed when the instrument is to 
 be placed in its case. In the case with the ophthal- 
 moscope there is a convex lens of + 16 D., which 
 will be described later. 
 
 The Luminous Ophthalmoscope (Figs. 3 and 
 4), DeZeng Patent. This instrument is the Lor- 
 ing ophthalmoscope just described with the addi- 
 tion of an electric light attachment and a mirror of 
 different size and shape. This mirror is plain, cir- 
 cular in form, 14 millimeters in diameter, with one 
 millimeter of its upper area cut away horizontally. 
 The flat top edge of the mirror is on a level with the 
 lower edge of the sight-hole in the ophthalmoscope ; 
 this mirror is placed at an angle of 43 degrees and 
 firmly secured to the instrument as it is never neces- 
 sary to tilt it. The observer in looking through the 
 sight-hole always looks over the mirror and never 
 through it. The handle of the instrument is hollow 
 and carries the electric wires to a small 5-volt lamp 
 
THE LUMINOUS OPHTHALMOSCOPE. 
 
 in the handle. Between the lamp and the mirror is 
 placed a very strong planoconvex lens. The rays 
 
 FIG. 3. FIG. 4. 
 
 DeZeng Luminous Ophthalmoscope. Two-thirds size. 
 
 of light from the filament falling upon the convex 
 lens are refracted very convergently and after re- 
 
8 THE OPHTHALMOSCOPE. 
 
 flection from the mirror converge to a point one 
 inch distant (Fig. 4). The luminous ophthalmo- 
 scope is so convenient for use in the wards of 
 a hospital, etc., and renders ophthalmoscopy so 
 much less difficult that the instrument at once com- 
 mends itself to every physician. This instrument 
 is ideal both for the direct and indirect method, 
 and has the following points of merit : The mirror 
 and light are stationary, thus giving the observer 
 any liberty of movement necessary without any loss 
 of the reflection from the mirror, the mirror never 
 requires any tilting, the brilliancy or intensity of the 
 illumination at the fundus by virtue of the light 
 being so close to the mirror far exceeds that of the 
 non-luminous instrument, and for the same reason 
 the size of the retinal illumination is made about 
 five times larger than that by the old style instru- 
 ment. The heat from the electric lamp is infinitesi- 
 mal. An electric light attachment is also made for 
 the Morton ophthalmoscope. 
 
 Electricity to supply the luminous ophthalmo- 
 scope may be furnished by a portable, storage, or 
 dry cell battery or by the Edison street current. 
 No matter what the supply may be, there should 
 always be a convenient rheostat attacluncnt at liand 
 so that the operator may know that he is not using 
 more current than the delicate lamp can possibly 
 endure. 
 
 The Thorner Ophthalmoscope is a large sta- 
 tionary instrument and an expensive one. It is 
 
HOW TO USE THE OPHTHALMOSCOPE. 9 
 
 used principally for magnification and class demon- 
 stration and is therefore not a part of the subject 
 matter of this manual. 
 
 How to Use the Ophthalmoscope. While the 
 beginner in ophthalmoscopy may see into an eye 
 the first time he makes the attempt, yet proficiency 
 with the use of the ophthalmoscope does not come 
 except by long and constant practice. The pupil 
 of an eye in health appears to an observer as black 
 (the eye of an albino excepted) ; this is due to the 
 fact that the observer's eye does not ordinarily in- 
 tercept any of the rays of light which return from 
 the eye. Rays of light entering an eye are returned 
 by that eye toward their immediate source and 
 therefore, if an observer wishes to see into or 
 study the interior of an eye, he must have his own 
 eye in the path of the returning rays. To accom- 
 plish this, the observer places a mirror in front of 
 his eye and reflects light into the pupil of another 
 eye, and as the rays return from the eye under ob- 
 servation, to the mirror from which they came, the 
 observer is able to receive some of these return 
 rays into his own eye through a small opening 
 which has been previously made in the mirror. 
 
 Several important matters should receive very 
 careful attention from the student or beginner be- 
 fore he attempts to use the ophthalmoscope, and 
 these points will be taken up seriatim. 
 
 The Room. This should be darkened by draw- 
 ing the shades or closing the blinds, the darker 
 
10 
 
 THE OPHTHALMOSCOPE. 
 
 the room the better, though it is not at all necessary 
 to have the walls painted black or draped in black 
 cloth. All lights except the one in use should, if 
 possible, be excluded from the dark room. If the 
 surgeon has a convenient room adjoining his office 
 and so desires, he may have it fitted up as a " dark 
 room " by having the walls and ceiling painted 
 black or draped in black felt, as just suggested. 
 
 The Light. A candle flame is almost useless 
 as it is not steady and moves with each current of 
 air. Gas is the most common and convenient illumi- 
 
 FIG. 5. Student lamp with cover chimney, on adjustable bracket. 
 
 nant, as nearly every house, even in the smallest 
 city, is piped for the purpose, and with rubber 
 tubing this may be brought to any adjustable stand. 
 A good quality of kerosene, in a modern lamp, may 
 be used if gas cannot be had. The student lamp is 
 good, but the flame is rather narrow. The student 
 lamp on a bracket is good if the cover chimney 
 
THE LIGHT. 
 
 I I 
 
 is used ( Fig. 5 ) . To use daylight it would be nec- 
 essary to have a round opening i l / 2 inches in di- 
 ameter in the closed blind or drawn shade, and this 
 opening would have to be exactly placed to meet 
 the conveniences of the office furniture. But day- 
 light is an uncertain quantity and cannot be relied 
 upon. There is one thing in favor of daylight how- 
 ever, and that is we can see 
 the eye ground in its natural 
 coloring and not altered by 
 the yellow coloring from the 
 reflected gas or lamp light. 
 The regular i6-candle-power 
 electric light with its narrozv 
 filament is somewhat objec- 
 tionable, though some obser- 
 vers use it, preferably with a 
 ground glass bulb or the coiled 
 filament. There is no objec- 
 tion to the Welsbach light if 
 the mantle is intact. What- 
 ever variety of light is used it 
 should have the qualifications 
 of being steady and bright, 
 a white light if possible. The Argand burner is 
 the most generally employed and most satisfactory 
 when on a convenient right-angled bracket ( Fig. 5 ) 
 which can be raised or lowered, and is capable of 
 lateral movement. The flame or electric light may 
 be exposed or covered with the iris diaphragm 
 
 FIG. 6. Author's Iris Dia- 
 phragm Chimney. 
 
12 THE OPHTHALMOSCOPE. 
 
 chimney (Fig. 6). If the luminous ophthalmoscope 
 is used, the question of light is settled at once, as 
 the filament gives a point of light which is perfect. 
 And furthermore, the light and mirror of this in- 
 strument being two fixed points, the observer has 
 no trouble in keeping his light in position for reflec- 
 tion and does not have to tilt his mirror, and for 
 bedside work the observer can follow the eye of the 
 most restless patient without losing the reflection. 
 
 Reflection from the Mirror. It has already 
 been stated that the concave mirror on the ophthal- 
 moscope has a radius of curvature of 40 centi- 
 meters (16 inches) and this means that if the light 
 is placed 20 centimeters (8 inches) from the mirror, 
 the rays of light would be reflected parallel. This 
 should be borne in mind for occasionally parallel 
 rays are required and this is a good way to obtain 
 them, and if divergent rays are required the light 
 must be placed at six or seven inches. If the 
 light is just 40 centimeters from the mirror, then 
 the reflected rays would have a convergence of 
 40 centimeters, as this distance represents the cen- 
 ter of curvature (c.c. in Fig. 29). 
 
 To summarize: 
 
 1. To obtain parallel rays of light reflected from 
 the mirror, place the light 20 centimeters distant. 
 
 2. To obtain divergent rays of light reflected 
 from the mirror, place the light closer than 20 
 centimeters. 
 
 3. To obtain convergent rays of light reflected 
 
MOVEMENT OF THE MIRROR. 13 
 
 from the mirror, place the light beyond 20 centi- 
 meters. The further the light is beyond 20 centi- 
 meters from the mirror, the greater the conver- 
 gence. 
 
 For most ophthalmoscopic work convergent rays 
 are employed, but when studying minute changes 
 in the retina, nerve-head, vitreous, etc., a faint 
 light is sometimes required, and at other times in 
 studying gross changes, the brightest or most in- 
 tense light obtainable is necessary ; the former may 
 be obtained by reducing the size of the flame in use, 
 or substituting a plane mirror. With the luminous 
 ophthalmoscope and a convenient rheostat a very 
 intense light, or one of moderate strength, may be 
 obtained. A concave mirror gives a more brilliant 
 illumination than a plane mirror, and each has its 
 particular advantages, as in certain instances, just 
 referred to; and mirrors with different radii of 
 curvature could be used to advantage, but too many 
 mirrors are an inconvenience. The Morton oph- 
 thalmoscope has a concave and also a plane mirror 
 which may be used independently. Light from the 
 concave mirror usually falls as a converging cone 
 of light, and the base of the cone is the mirror, but 
 when examining an eye by the direct method (Fig. 
 8) then only those rays around the sight-hole of 
 the mirror enter the patient's pupil. 
 
 Movement of the Mirror. The mirror must 
 always be tilted toward the light. When looking 
 into the eye from a short distance and before be- 
 
THE OPHTHALMOSCOPE. 
 
 ginning a study of the fundus of the eye, it is well 
 to reflect the light into the eye by moving or rotat- 
 ing the handle of the ophthalmoscope, so that the 
 light passes through the different meridians, hori- 
 
 FIG. 7. The Author's Schematic Eye. 
 
 zontally, vertically and diagonally, and in this way 
 opacities and the character of the refraction of the 
 eye, may be promptly recognized. These conditions 
 will be referred to elsewhere in the text. 
 
 Schematic Eye (Fig. 7). Before hurrying to 
 
MYDRIATICS. 15 
 
 look into a patient's eye, the beginner will feel 
 much more confident if he has acquired previous 
 experience, by looking into one of the many sche- 
 matic eyes to be found in the shops. While ad- 
 mitting that the schematic eye has its disadvan- 
 tages or imperfections and is not equal to the 
 human eye in all particulars, yet it has just those 
 qualifications which make it so essential for the 
 beginner with the ophthalmoscope, namely, (a) it 
 does not wink; (b) it does not suffer from photo- 
 phobia (dread of light) ; (c) it does not suffer from 
 lacrimation; (d) it does not get tired; (e) its retina 
 does not suffer from light stimulus; and, best of 
 all, (/) it has a dilated pupil. 
 
 Mydriatics. (Drugs which dilate the pupil.) 
 When using the ophthalmoscope to examine the 
 live eye, it is certainly an advantage to have the 
 pupil dilated, especially so for the novice, but this 
 condition is often a great inconvenience to the pa- 
 tient, and some patients will positively refuse to 
 have any " drops " used, while others will permit 
 the use of the drops, but find fault on account of 
 the resulting discomfort, and others will have a 
 dread of resulting impaired sight, or another 
 patient might have glaucoma (Chapter XI. and 
 Plate XII.), a disease which would preclude the 
 use of a drug which would crowd the iris into the 
 angle of the anterior chamber. Fortunately for the 
 beginner as well as for the expert, with the ophthal- 
 moscope, the disc (optic nerve head) is the princi- 
 
l6 THE OPHTHALMOSCOPE. 
 
 pal part of the fundus usually affected by glaucoma, 
 and it is this part which is most easily examined 
 without a mydriatic. The great thing therefore 
 for the student is to learn to use the ophthalmoscope 
 on the schematic eye and when he has mastered 
 the technic, to then learn as soon as possible to ex- 
 amine the same schematic eye by adjusting to it 
 a small pupil made by cutting a 3^ millimeter 
 round opening in a card. After some considerable 
 practice in this way, sufficient skill will have been 
 obtained whereby the student will be able to tell 
 when looking into the human eye whether there 
 is any disease present, and whether this disease 
 precludes the use of a mydriatic or if it will 
 be necessary to employ a mydriatic so that the 
 interior of the eye may be studied more mi- 
 nutely. If glaucoma is not present and there 
 are no symptoms of glaucoma, then if necessary 
 for further examination, or refraction or further 
 study, a mydriatic may be employed. One of the 
 safest mydriatics, and one that has but a brief effect 
 and appears to have the least amount of danger at- 
 tached to its use, as far as the production of glau- 
 coma is concerned, is a fresh 4 per cent, solution 
 of cocain ; one or two drops of this solution should 
 be placed on the upper part of the eyeball as the 
 upper lid is held upwards and the patient looks 
 downwards; the solution passing freely over the 
 cornea and its margins is soon absorbed. Cocain 
 used in this way will give a maximum dilation of 
 
MYDRIATICS. 17 
 
 the pupil in about twenty minutes. This dilation 
 will last for a few hours ordinarily, but as cocain 
 has very little, if any, effect on the accommodation, 
 the patient will not object to the temporary photo- 
 phobia, which passes away as soon as the pupil 
 regains its normal size. After the examination has 
 been completed under cocain mydriasis, the writer 
 urges and advises counteracting the mydriatic ef- 
 fect by instilling a weak solution of eserin, one 
 drop of a l / grain to the ounce of distilled water. 
 This is simply a matter of extreme prudence and 
 can do no harm, but might possibly do an immense 
 amount of good. A 2 per cent, solution of euthala- 
 min may be used in preference to cocain. If there 
 is any disease of the interior of the eye that is 
 injuring the sight or may injure the sight later 
 on, then it is certainly the part of caution on the 
 part of the surgeon to so inform the patient before 
 using a mydriatic, so that if the patient's vision 
 becomes impaired later on, the surgeon may not be 
 accused of any wrong doing from having used 
 drops. In competent hands there is very little if 
 any danger from the use of mydriatics. 1 One drop 
 
 1 Hughlings-Jackson, Lectures on Optic Neuritis, Med. Times and 
 Gazelle, September 16, 1871 : " If we use the ophthalmoscope, or if 
 we use atropin, or if we apply a blister to the head, or adopt any new 
 kind of treatment, the patient may blame us for his blindness, if he 
 saw well before such procedures. A patient who reads the smallest 
 print and supposes his sight to be good, may have double optic neu- 
 ritis. The use of atropin affects his sight for near objects gravely, 
 and if, from advance of the neuritic process, what I may call ' retinal 
 sight,' fails before the effect of the atropin has passed off, he very 
 
1 8 THE OPHTHALMOSCOPE. 
 
 of a solution of homatropin hydrobromate (one 
 grain to the ounce of water) will answer the same 
 purpose as the cocain solution, but the effect is more 
 lasting and has some action on the accommodation. 
 The Observer. If the observer has any de- 
 cided refractive error, he should wear his correct- 
 ing glasses, and at the same time should learn as 
 soon as possible to relax his accommodation when 
 using the ophthalmoscope, so that when he looks 
 at the eye ground and has to turn a lens in front 
 of the sight-hole to get a clear picture, he will 
 know at once that the lens so used is an approxi- 
 mate estimate of the refraction of the eye being 
 examined. As a general rule, the beginner's 
 accommodation makes him apparently myopic or 
 near-sighted, as he strains his eye in his efforts to 
 see the nerve or fundus about an inch or two dis- 
 tant, but he need not worry or make himself un- 
 happy about this, but go ahead and use any lens 
 that will enable him to see the nerve and eye-ground 
 or whatever he wishes-, and later on he will learn 
 to relax his accommodation and then use a weaker 
 
 naturally blames us for the subsequent permanent affection of his 
 sight. A patient, when asked how long his sight had been bad, re- 
 plied : ' Only since the drops had been put in.' We must, then, when 
 we discover neuritis, sight being good, tell the patient that his eyes 
 are not really good, and that we are anxious about his sight. 
 Whether we give this warning or not, we shall be blamed by an unin- 
 telligent patient for ' tampering with his eyes.' We must, however, 
 act for our patient's good, regardless of selfish considerations. In 
 very many cases we can see enough for diagnostic purposes without 
 using atropin." 
 
THE OBSERVER. 19 
 
 lens at the sight-hole. However, he should not de- 
 lay in his efforts to learn to relax his accommoda- 
 tion and the ability to do so, he will find one of the 
 most difficult things in the whole of ophthalmo- 
 scopy, and it will take him some time to accomplish 
 it. There are three reasons for the beginner to 
 wear any necessary correcting glasses and to learn 
 to relax his accommodation, i. e., (a) that he may 
 see clearly and with the least amount of effort; his 
 eyes, in other words, should be in an emmetropic 
 condition (see Emmetropia, p. 71 ) ; (b) that he may 
 not develop headaches and eye strain, and (c) that 
 he may not count his own refractive error as be- 
 longing to, or as a part of the patient's eye con- 
 dition, which he would be very likely to do, if 
 he did not wear his glasses or make due allow- 
 ance for his own refractive error. A good way 
 for the observer to learn to relax his accommo- 
 dation, is to place a pair of plus three diopter 
 spheres over his correcting glasses and practice 
 reading ordinary sized print, such as is used in 
 this book, and to read it at thirteen inches distant, 
 which is the principal focal distance of the spheric 
 lenses used. Another way to relax the accommo- 
 dation when looking into the eye, is to imagine 
 that the eye ground or disc is very distant, in 
 place of being an inch or so away. Another very 
 good way to accomplish the same thing, is to learn 
 at once to keep both eyes wide open. Too many 
 students will insist upon squinting one eye shut or 
 
2O THE OPHTHALMOSCOPE. 
 
 holding it shut while using the other eye, and the 
 result is, they will accommodate several diopters 
 more than there is any real necessity for doing. 
 This habit of squinting one eye is a very bad habit 
 indeed and one which many students have had 
 great difficulty to overcome. Another and excel- 
 lent way to learn to relax the accommodation, and 
 one which others have appreciated, is to practice 
 on the schematic eye. The schematic eye has an 
 index which records emmetropia, hypermetropia, 
 and myopia, so the beginner may set the eye at any 
 number of diopters of hypermetropia or myopia and 
 then taking the ophthalmoscope in hand, he must 
 learn to see the eye ground of the schematic eye 
 with the lens at the sight-hole in the ophthalmoscope 
 which corresponds to the amount of the refractive 
 error indicated by the index. For instance, if the 
 schematic eye is set for 3 D. of hypermetropia, then 
 the + 3 D. must be turned into the sight-hole of 
 the ophthalmoscope, when the observer views the 
 eye ground, and he must learn to see the details 
 of the fundus with this + 3 D. and no other lens. 
 The approximate estimation of the various refrac- 
 tive errors, will become comparatively easy as soon 
 as the student learns to relax his accommodation. 
 This will be referred to later (Chapter II.). 
 
 Position of the Observer. The observer should 
 be comfortably seated at the side of the patient cor- 
 responding to the eye he is to examine, if examin- 
 ing the right eye, the observer should be on the 
 
POSITION OF LIGHT. 21 
 
 patient's right; if the left eye, then on the pa- 
 tient's left side. When examining the right eye 
 the ophthalmoscope is held in the right hand 
 and before the right eye (Fig. 8) ; and in the left 
 hand and before the left eye when examining the 
 left eye. The examiner's eye should be a little 
 above or higher than the patient's eye. The ex- 
 aminer's head should be tilted slightly in the di- 
 rection of his shoulder corresponding to the eye 
 he is using (Fig. 9). 
 
 To meet all the requirements for the comfort of 
 the observer, he will do well to have a stool with 
 revolving top or seat, that he may adjust his posi- 
 tion promptly and to suit the individual patient. 
 
 Position of Light. If the mirror on the oph- 
 thalmoscope is of 40 centimeter radius, then to 
 begin the examination, the light should be about 
 this distance to one side and back of the patient 
 and on a level with the patient's eye ; in other words, 
 the light should be placed at an angle of 45 degrees 
 with the plane of the patient's face, so as to illumi- 
 nate the outer half of the eye-lashes of the eye to be 
 examined, and it may be well also to have the tip 
 of the patient's nose illuminated at the same time 
 (Fig. 8). The beginner should appreciate these 
 points of position, for if the light cannot take 
 this direction from the flame, and the flame should 
 be back of the patient's ear, then there cannot be 
 any reflection from the mirror when close in front 
 of the patient's eye, as the temple and ear would 
 
22 THE OPHTHALMOSCOPE. 
 
 cut off the light from the mirror. Many students 
 when learning to use the ophthalmoscope, neglect 
 this position of the light, and when they get close 
 to the eye to examine it, lose the reflection and 
 wonder why they lose it. 
 
 Position of Patient. The patient should be 
 seated in a comfortable chair without arms (Fig. 
 8), and be instructed to look straight ahead into 
 vacancy, or across the room at some large object 
 about on a level with his eyes; in this way his ac- 
 commodation will relax considerably and his pupil 
 will be larger. He is also instructed to change the 
 direction of his vision only when told to do so. 
 Under no circumstances should the patient be al- 
 lowed to look at a light or into the mirror, as the 
 light stimulus falling upon the macula, will cause 
 the pupil to contract. If the patient is a child and 
 will not concentrate the vision as just directed, 
 then it will be necessary to have some one stand 
 back of the observer, and, by snapping the fingers 
 or clapping the hands, or dangling a bunch of keys 
 or a watch, attract the child's attention, and thus 
 keep it from looking into the mirror. If the pa- 
 tient has a squint, it will be necessary when ex- 
 amining the squinting eye to have the fixing eye 
 covered with a folded handkerchief, or held gently 
 shut with the finger, or shielded with a card, and 
 in this way the squinting eye will ordinarily turn 
 straight and the observer will have an opportunity 
 to examine it. With children it may be necessary 
 
POSITION OF PATIENT. 
 
24 THE OPHTHALMOSCOPE. 
 
 to employ the indirect method (Fig. 13). The 
 patient and observer should each keep both eyes 
 open. The one exception to this, is when the pa- 
 tient has a squint as just stated. 
 
 How to Hold the Ophthalmoscope. The ob- 
 server should hold the ophthalmoscope as vertical 
 as possible and have the sight-hole directly in front 
 
 FIG. 9. Correct position of holding the ophthalmoscope. Top of in- 
 strument resting in the hollow of the brow and the side resting on or 
 touching the side of the nose. Ophthalmoscope is held vertically before 
 the right eye and the observer's head is inclined slightly toward the 
 right shoulder with the arm close to the side. Without changing the 
 position of the instrument the observer can easily turn the milled wheel 
 with the tip of his index finger, as shown in Fig. 10. 
 
HOW TO HOLD THE OPHTHALMOSCOPE. 25 
 
 of his pupil and close to his eye. The upper mar- 
 gin of the ophthalmoscope resting in the hollow 
 of the brow, and the side of the instrument against 
 the side of the nose (Fig. 9). The observer's arm 
 should be at his side and not form an angle with 
 
 FIG. 10. Very faulty position of holding the ophthalmoscope for direct 
 examination. The arm and hand and handle of the ophthalmoscope are 
 turned outward. The index finger, however, is in the correct position 
 for turning the milled wheel, as referred to in Fig. 9. 
 
 his body. If the arm of the hand holding the 
 ophthalmoscope is bent outward (Fig. 10), and 
 not kept vertical, then when the observer gets 
 close to the patient's eye his hand is liable to, and 
 
 4 
 
26 THE OPHTHALMOSCOPE. 
 
 very likely will, strike the patient's nose, an evi- 
 dent indication of want of skill or experience. 
 
 How to Use the Ophthalmoscope. There are 
 two ways, or methods, of using the ophthalmo- 
 scope; one is called the direct, and the other the 
 indirect method. The direct method (Fig. 8) 
 gives an erect, virtual, and enlarged image of the 
 interior of the eye, while the indirect method (Fig. 
 13) gives or produces an inverted and real image, 
 but much less magnified than the direct. The 
 principle of the direct method is similar to a sim- 
 ple microscope, and the indirect to a compound 
 microscope. 
 
 The Direct Method. Executing the several 
 details as just given as regards the room, the 
 light, etc., the observer begins his examination 
 at a distance of 25 or 30 centimeters from the 
 eye, never closer, and at this distance he re- 
 flects the light into the eye and observes a " red 
 glare " which occupies the previously black pupil. 
 This red glare is called the " reflex " and is due 
 to the reflection from the choroidal (vascular) 
 coat of the eye. The color of this reflex varies, 
 (a) with the size of the pupil, (b) transparency 
 of the media (cornea, aqueous, lens and vitreous), 
 (c) the refraction, (d) the amount of pigment in 
 the eye ground, and (e) with detachment of the 
 retina, growths, etc. Having obtained the reflex, 
 it will be well for the observer to practice keeping 
 the light on the pupil, by changing his distance 
 
SIZE OF IMAGE. 2J 
 
 while still holding the ophthalmoscope in front of 
 his eye, approaching the eye as close as an inch 
 or two; this must be done slowly and not with a 
 rush. The direct method, therefore, is so called 
 from the fact that the observer looks directly into 
 the eye. A detailed description of the eye ground 
 is given in Chapter IV. 
 
 Size of the Image of the Eye Ground. In this 
 direct method of looking into the eye, the optic 
 nerve head, retinal vessels, etc., are all enlarged 
 on account of the strong refracting or magnify- 
 ing power of the cornea and lens; the result is, 
 that on account of the enlargement the eye ground 
 seems to be at some distance behind the eye (Figs, 
 ii and 12). The nerve head in an emmetropic 
 eye, as seen with the ophthalmoscope, appears 
 about 25 millimeters in diameter, and about 250 
 millimeters distant. The actual distance of this 
 nerve head from the nodal point in the lens, is 
 about 15 millimeters, therefore the actual size of 
 the nerve head must be 15/250 of 25, or 3/2, or 
 1.5 millimeters; then 15, the nodal distance, is to 
 the supposed distance, 250 millimeters, as the ac- 
 tual size, 1.5 is to the magnified size, 25; which is 
 16.6, the magnification; or, to put it mathematically 
 
 15:250:: 1.5:25=16.6. 
 
 In other words, when the emmetropic nerve head 
 is observed, it appears about 16.6 times larger than 
 it actually is. The disc of a hypermetropic eye 
 
28 
 
 THE OPHTHALMOSCOPE. 
 
 appears smaller than that of an emmetropic eye, 
 and the disc of a myopic eye appears larger. Just 
 as the nerve head appears magnified, so the ves- 
 sels of the eye ground appear correspondingly 
 
 \U n/ uj i 
 
 S -S S o S 
 
 iT 
 
 E " 
 
 o o 
 
 c 
 
 S g 
 
 82 
 
 = c. = 
 
 rt ci* 
 
 rt -2 
 
 ^ x ;C 
 
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 enlarged and this becomes extremely interesting, 
 when it is known that some of the small vessels 
 of the retina are less than 1/700 of an inch in 
 diameter, and the largest vessels less than i/ioo 
 
THE INDIRECT METHOD. 
 
 of an inch. The capillaries of the retina in health 
 are invisible with the ophthalmoscope. 
 
 .X <0 
 
 I) <U 
 60 
 
 43 Z O 
 
 U _ M 
 
 11 en -4~> 
 
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 s & s 
 
 53 " 
 
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 Ib 
 
 The Indirect Method (Fig. 13). To examine 
 the eye ground by the indirect method, the ob- 
 server requires a convex lens of about 13 diopters 
 in addition to his ophthalmoscope. The convex 
 
THE OPHTHALMOSCOPE. 
 
 C rfi P 
 
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 2 
 
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THE INDIRECT METHOD. 31 
 
 lens which comes in the case with the ophthalmo- 
 scope (+ 16 D.) is usually too strong and of too 
 small aperture, and on this account the writer 
 prefers his condensing lens, as pictured in Fig. 
 
 FIG. 14. Author's Condensing Lens. Two-thirds size. 
 
 14 (reduced one-third in size). This lens has a 
 metal rim which assists in preserving the lens 
 from breakage and a convenient handle which 
 makes it much easier to manipulate. To make 
 the indirect examination, the light (as bright as 
 possible) may be placed, (i) as in the direct 
 method, and the observer may keep his position 
 at the side of the patient corresponding to the 
 eye to be examined, or (2) the light may be placed 
 above the patient's head, or (3) on a level with 
 the top of the patient's head. It is customary 
 with many observers to take a seat in front of 
 the patient, but this is not at all necessary, and in 
 fact it is sometimes quite unnecessary and rather 
 to be avoided. Whether the observer sits at one 
 side or in front of the patient, his eye should be 
 
32 THE OPHTHALMOSCOPE. 
 
 about 16 or 20 inches from the eye under obser- 
 vation, when beginning the examination. At this 
 distance and the light in position, with the patient's 
 right eye to be examined, the observer holds the con- 
 densing lens with his thumb and index finger of 
 his left hand, and rests his little and ring fingers 
 on the patient's right temple or forehead, so that 
 the condensing lens is about two or three inches 
 from the eye. Then, with the ophthalmoscope 
 held in the usual position before his right eye, the 
 observer reflects the light through the condens- 
 ing lens into the eye and very slowly approaches 
 or moves back from the eye until he recognizes 
 a retinal vessel or the optic disc; he must remem- 
 ber, however, that he is not looking into the eye, 
 but is viewing an aerial image of the eye ground 
 formed in the air between the condensing lens and 
 the ophthalmoscope. This image, besides being 
 aerial, is inverted, and has undergone lateral in- 
 version, so that the right side of the eye ground 
 becomes the left side of the image, and the left 
 side of the eye ground becomes the right side of 
 the image, the upper portion of the eye ground 
 becomes the lower portion of the image, the lower 
 portion of the eye ground becomes the upper por- 
 tion of the image (Fig. 15). While making this 
 examination the patient is directed to look straight 
 ahead, then to gradually turn the eye in various 
 directions to suit the observer's wishes. In this 
 way, various portions of the eye ground are care- 
 
THE INDIRECT METHOD. 
 
 33 
 
 fully inspected or studied. The disc is generally 
 the principal part of the eye ground or part of 
 the image first looked for, and to bring it into 
 
 5 
 
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 73 
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 view at once the patient is told to look a little to 
 the observer's right when examining the right 
 eye, and to the observer's left when examining 
 the left eye. It has already been mentioned that 
 
34 THE OPHTHALMOSCOPE. 
 
 the patient should be told to rotate his eye in dif- 
 ferent directions as the observer tells him, but 
 this is not always satisfactory, as many patients 
 will turn the eye too far, and therefore it may be 
 just as well to have a nervous patient fix his gaze in 
 one direction and let the observer learn to move the 
 lens, slowly upward, downward, inward, outward 
 and diagonally. The observer must also learn to 
 move the lens closer to the eye or to bring it away 
 from the eye, as necessary, and in this way get the 
 most distinct image. It may be necessary at times to 
 rotate the lens on its axis. The stronger the con- 
 densing lens employed, the larger the view of the 
 fundus, but the details will be smaller; the weaker 
 the condensing lens, the smaller will be the view 
 of the fundus, but with larger, magnified individ- 
 ual points in the image- To relieve the observer's 
 accommodation and to magnify the aerial image 
 la plus four lens is usually placed at the sight-hole 
 of the ophthalmoscope. This plus four lens, cor- 
 responds to the eye piece of the microscope; when 
 examining eyes that are highly myopic it may be 
 omitted. Practicing the indirect method, the ob- 
 server sees a larger part of the eye ground at one 
 time than by the direct method, but it is not mag- 
 nified to the same extent as in the direct method. 
 It is a method, however, that is easier and more 
 convenient in many ways than the direct, and yet 
 many ophthalmologists neglect to use it. It is a 
 method too that does not necessarily require a 
 
THE INDIRECT METHOD. 35 
 
 dilated pupil. It is a method that is occasionally 
 of great convenience in the clinic, when objection- 
 able (unclean) patients come for examination, and 
 the physician desires to keep at a good distance. 
 Both the direct and indirect methods should be 
 practiced and they are comparatively easy when 
 the patient has large pupils, but with very small 
 pupils a detailed and satisfactory examination, 
 while it may be obtained, is often difficult. When 
 practicing the indirect method, the observer should 
 keep both eyes open as with the direct method. 
 And he may use his right eye when looking at the 
 patient's right eye, and his left when looking at 
 the patient's left, or he may use his right eye in 
 each instance. This is purely a matter of conveni- 
 ence. While viewing the disc with the indirect 
 method, some approximation of the refraction may 
 be obtained when the condensing lens is gradu- 
 ally withdrawn from the eye. 
 
 1. When the image of the disc appears to in- 
 crease in size, the refraction is myopic; and if 
 
 2. The image of the disc diminishes in size, the 
 refraction is hypermetropic ; and if 
 
 3. The image of the disc does not change in 
 size, it is emmetropic. 
 
 4. For astigmatism. If the image of the disc, 
 which is the part usually selected for making this 
 estimate, appears of uniform size in one meridian, 
 whether the condensing lens is brought closer to 
 or removed from the eye, then that meridian is 
 
36 THE OPHTHALMOSCOPE. 
 
 emmetropic, but if the meridian grows smaller as 
 the lens is withdrawn from the eye, then that me- 
 ridian is hypermetropic, if it grew larger then it 
 would be myopic. Withdrawing the condensing 
 lens and all meridians appear to grow smaller but 
 one more so than the other then the condition is 
 one of compound hypermetropia. If all meridians 
 grew larger but one more so than another then 
 the condition would be one of compound myopic 
 astigmatism. 
 
 The image growing smaller in one meridian and 
 larger in the other, as the condensing lens is with- 
 drawn from the eye, would signify mixed astig- 
 matism. 
 
 To study the presence of an elevation of the 
 disc or the elevation of a growth or detachment, 
 or to study the depth of a cupping of the disc, then 
 after getting the aerial image and moving the ob- 
 jective lens from side to side and up and down, 
 the near points of the image will appear to move 
 faster than the points beyond; this is known as 
 the parallactic movement. 
 
 The Size of the Image of the Eye Ground. 
 This depends upon the refraction of the eye and 
 the distance of the convex lens from the eye under 
 examination. In the standard (emmetropic) eye 
 the size of the image is always the same, no mat- 
 ter how far away from the eye the convex lens is 
 held. To estimate the size of the image, as seen 
 in the standard eye, all that is necessary to know 
 
OBLIQUE ILLUMINATION. 37 
 
 is the principal focus of the condensing lens em- 
 ployed: if + 13 D., then the image is formed at 
 about 75 millimeters (three inches), and remem- 
 bering that the nerve head in the standard eye is 
 15 millimeters back from the nodal point, the size 
 of the image will be to the size of the nerve head, 
 (if that is what is looked at in the image) as their 
 respective distances from the nodal point and con- 
 densing lens, or as 15 is to 75, which equalsj^ the 
 magnification. Comparing the two methods of ex- 
 amination, the direct and the indirect, the former, 
 while it gives a smaller view of the fundus, yet it 
 is greatly magnified, sixteen times as compared to 
 five by the indirect, hence for the examination of 
 a minute point, such as a hemorrhage or growth 
 or foreign substance, small detachment, etc., the 
 direct method, is far superior to the indirect. The 
 direct method gives an erect image and the ob- 
 server recognizes at once each point of the eye 
 ground in its correct anatomic position. With the 
 direct method the observer can turn a lens into 
 the sight-hole of the ophthalmoscope, which ap- 
 proximately corrects the refractive error of the 
 eye under observation. 
 
 Oblique Illumination, or Focal Illumination. 
 The cornea, aqueous humor, lens and anterior por- 
 tion of the vitreous body, should have careful con- 
 sideration, for a clear view of the eye ground 
 depends upon the transparency of these media. 
 This is a most important part of the examination 
 
THE OPHTHALMOSCOPE. 
 
O15LIOUK ILLUMINATION. 
 
 39 
 
 H <L> H 
 
 *- <n 
 
 '" 
 'S - 
 
4O THE OPHTHALMOSCOPE. 
 
 and the cautious physician will not omit this part 
 of the study, especially if a clear view of the eye 
 ground, cannot be obtained with the ophthalmo- 
 scope. This method of examination is called the 
 oblique or focal, because the light is usually con- 
 densed from the side by means of a lens and made 
 to fall successively upon and into the cornea, aque- 
 ous humor, lens and anterior portion of the vitre- 
 ous humor. The source of light or illumination, 
 lamp or gas flame, is placed one or two feet from 
 the head of the patient and to the side correspond- 
 ing to the eye to be examined, and at the same 
 time a little to the front and above the level of 
 
 the eye (Fig. 16). A con- 
 vex lens of short focus, 
 + 13 D. or + 16 D., is held 
 in the hand of the surgeon, 
 between the light and the 
 eye under examination, and 
 about three inches from the 
 eye, so that the converging 
 
 FIG. 1 8. Loupe. J 
 
 pencil from the lens is 
 
 thrown upon and into the eye. As the lens is 
 moved from side to side and up and down and 
 diagonally, each part of the cornea, aqueous and 
 iris may be carefully inspected. Or, in place of 
 moving the condensing lens, it may be held still, 
 and the patient told to rotate the eye in certain 
 given directions. When a minute point, is to 
 be carefully examined by itself, then the con- 
 
OBLIQUE ILLUMINATION. 
 
 U to 
 
 J5 C 
 
 H c 
 
 
 2 i 1 
 
 o rt ~ 
 
 e. ^ 
 
42 THE OPHTHALMOSCOPE. 
 
 densing lens, must be moved closer to the eye or 
 away from it until the apex of the cone of con- 
 verging rays will fall directly upon the point se- 
 lected. To study the anterior layers of the vitre- 
 ous and the peripheral portions of the lens of the 
 eye, it is often necessary to dilate the pupil, and 
 the light must now be placed a little more to the 
 
 FIG. 20. Cover chimney with condensing lens. 
 
 front of the eye under examination (Fig. 19). 
 The patient's head should also be tilted a little 
 backwards and the observer must get a little to 
 one side, so as not to intercept the rays from the 
 light. If the observer wishes to magnify the part 
 under examination, he may do so by holding an- 
 other lens of the same focus, or of stronger power, 
 between the thumb and index finger of his other 
 hand, and gaze at the spot through this second 
 lens (Fig. 17). Another convenient way to mag- 
 nify the part looked at, or to examine for foreign 
 substances (cinders, etc.) is to use a " loupe." This 
 
OBLIQUE ILLUMINATION. 43 
 
 is pictured in Figs. 18 and 19. A very good way to 
 condense the light onto the cornea when the sur- 
 geon wishes to use his hands for another purpose, 
 for instance when removing a foreign substance, 
 is to have a strong lens from the trial case placed 
 in the notch in front of the iris diaphragm, on the 
 cover chimney, or to use a cover chimney with tele- 
 scopic attachment as shown in Fig. 20. 
 
CHAPTER II. 
 
 OPTICS. LIGHT. REFLECTION. REFRACTION. LENSES. 
 HYPERMETROPIA. MYOPIA. ASTIGMATISM. ESTIMAT- 
 ING THE REFRACTION BY THE DIRECT AND INDIRECT 
 METHODS AND RETINOSCOPY. 
 
 To assist the beginner in ophthalmoscopy, who 
 should have a general knowledge of the optic prin- 
 ciples on which the ophthalmoscope is constructed, 
 and also the optic principles of the eye he is to ex- 
 amine, the writer has prepared this chapter, bor- 
 rowing freely from his work on " Refraction and 
 How to Refract." 
 
 Light. Light is that form of energy which 
 acting upon the organ of sight renders visible the 
 object from which it proceeds. This energy is prop- 
 agated in waves in all directions from a luminous 
 body and with a velocity in a vacuum of 186,000 
 miles in a second of time. In the study of a lumi- 
 nous substance such as a candle, lamp or gas flame, 
 the substance itself must not be considered as a sin- 
 gle source of radiation, but as a collection of innu- 
 merable points of light, from every one of which 
 waves or rays proceed in all directions and cross one 
 another as they diverge from their respective points. 
 In other words, all rays of light proceeding from a 
 point are divergent. 
 
 Intensity of Light. The intensity of light di- 
 
 44 
 
RAYS. 45 
 
 minishes as the square of the distance ; for example, 
 if an object is twice as far from a luminous body 
 as another of the same size, it will receive one- 
 fourth as much light as the latter. Fig. 21 shows 
 
 FIG. 21. 
 
 rays of light illuminating a card about one inch and 
 a half away from the candle flame, and the second 
 card just the same size, at twice this distance re- 
 ceives only one-fourth the amount of illumination. 
 If the second card had been four times as far away 
 it would have received only one-sixteenth as much 
 illumination. 
 
 Ray. Ray from radius, meaning a straight 
 line, is a word used in optics in preference to 
 wave, and means the smallest subdivision of light. 
 Rays of light are considered as incident, emergent, 
 reflected, refracted, divergent, parallel and con- 
 vergent. 
 
 Incident Rays. Rays of light are said to be 
 incident when they strike or fall upon the surface 
 of an object. Rays of light from the candle in 
 Fig. 21 falling upon the card are incident rays. 
 These rays are also spoken of as divergent rays. 
 
 Emergent Rays. Rays of light are emergent 
 
4 6 
 
 THE OPHTHALMOSCOPE. 
 
 when they have traversed or passed through a 
 transparent substance. This is demonstrated or 
 shown by the incident or parallel rays in Fig. 22, 
 
 FIG. 22. 
 
 which have undergone refraction by the plano- 
 convex lens, and are now emergent; these latter 
 rays in this instance are also spoken of as con- 
 vergent. 
 
 Reflected Rays. Rays of light are reflected 
 when they rebound from a polished surface. 
 This is shown in Fig. 23. See Laws of Reflection. 
 
 FIG. 23. 
 
 Refracted Rays. Rays are refracted when they 
 are deviated from their course in passing through 
 
RAYS. 47 
 
 any transparent substance. This is shown in 
 Fig. 22; as the rays emerge from the lens they 
 are deviated from their course. 
 
 Divergent Rays. Rays of light proceed diver- 
 gently from any luminous substance, but in the 
 study of refraction only those rays which proceed 
 from a point closer than six meters (20 feet) are 
 spoken of as divergent. This is also shown in 
 Fig. 21 as the rays diverge from the candle flame 
 and are also spoken of in this instance as incident. 
 
 Parallel Rays. The greater the distance of any 
 luminous point, the more nearly do its rays ap- 
 proach to parallelism; this is evident in a study of 
 rays coming from such distant sources as the sun, 
 moon and stars. For all practical purposes in the 
 study of refraction, rays of light which proceed 
 from a distance of six meters or more are spoken 
 of as parallel, although this is not absolutely cor- 
 rect, as rays of light at this distance still maintain 
 a slight amount of divergence. If the pupil of the 
 emmetropic eye is represented by a circular open- 
 ing four millimeters in diameter, then the rays of 
 light from a luminous point at six meters (6,000 
 millimeters) will have a divergence of 4/6,000 
 when they enter such a pupil. 
 
 Convergent Rays. Convergent rays are the re- 
 sult of refraction through a convex lens or reflec- 
 tion from a concave mirror. Convergent rays are 
 not a condition of nature. Fig. 22 shows the rays 
 of light converging as they emerge from the lens, 
 
48 THE OPHTHALMOSCOPE. 
 
 and Fig. 23 shows the rays of light converging as 
 they rebound from the concave mirror. 
 
 A Beam of Light. This is a series or collection 
 of parallel rays. Fig. 22, if reversed, shows rays 
 of light diverging from a point and after refrac- 
 tion by the plano-convex lens are made parallel. 
 A Pencil. A pencil of light is a collection of 
 divergent or convergent rays. Convergent rays 
 are those which tend to a common point, whereas 
 
 divergent rays are 
 those which proceed 
 from a point. This 
 point is called a ra- 
 diant point. The 
 rays from the candle 
 
 FIG. 24. 
 
 flame in Fig. 24 form 
 
 a divergent pencil, the point in the flame is the 
 point of the pencil or the radiant point. The rays 
 of light coming together after leaving the lens, as 
 shown in Fig. 22, form a convergent pencil. The 
 point of this converging pencil is called a |oettsr 
 
 A Focus. This is the point of a converging or 
 diverging pencil. The center of a circle is also 
 spoken of as a focus. Focus means " fire," and 
 is referred to as the burning point of a convex lens. 
 There are two kinds of foci. 
 
 A Positive or Real Focus. This is the point to. 
 which rays of light are directed after passing 
 through a convex lens ( Fig. 22 ) , or- the point to 
 
REFLECTION. 49 
 
 which rays of light are directed after reflection 
 from a concave mirror (Fig. 23). A positive or 
 real focus may be described as the actual meeting 
 
 ofrays of light; such a focus may be thrown upon 
 a screen. 
 
 A Negative or Virtual Focus. This is the 
 point from which rays appear to diverge after pass- 
 ing through a concave lens (Fig. 45) or after re- 
 flection from a convex mirror (Fig. 31) or after 
 refraction through a convex lens when the light 
 or object is closer to the lens than its principal focus 
 (Fig. 47), or after reflection from a concave mir- 
 ror when the light or object is closer to the mirror 
 than its principal focus (Fig. 28). A virtual or 
 negative focus cannot be thrown upon a screen. 
 
 Reflection. From the Latin " reflectere," to re- 
 bound. This is the sending back of the rays of 
 light by the surface on which they fall into the 
 medium through which they came. This is the 
 study of catoptrics (from the Greek x ( * T07rT P ov 
 meaning "a mirror"). While most of the rays 
 of light falling upon a transparent substance will 
 pass through it, yet some portion of the rays are 
 reflected and it is by virtue of these reflected rays 
 that surfaces are rendered visible. A substance 
 that could transmit or absorb all the rays of light 
 which came to it (if such a substance existed) 
 would be invisible. Fig. 33 shows a ray of light 
 incident on a piece of clear glass ; a portion of this 
 ray passes through, emerges and is refracted, but 
 6 
 
5O THE OPHTHALMOSCOPE. 
 
 at the same time all of the incident ray did not 
 pass through the glass, a portion of it rebounded 
 or was reflected, and in this way the glass is made 
 or rendered visible. Likewise the ray P, while 
 it strikes the glass perpendicularly, a portion of 
 it passes through the glass and a portion rebounds 
 in the same perpendicular, and if the eye was look- 
 ing down onto or into or through the glass, the 
 glass itself would be rendered visible. 
 
 Laws of Reflection. ( i ) The angle of reflection 
 is equal to the angle of incidence. (2) The re- 
 flected and incident rays are in the same plane 
 with the perpendicular to the surface (Fig. 25). 
 The incident ray / falling upon the plane mir- 
 ror AB at D becomes 
 the reflected ray R. 
 The perpendicular line 
 P divides the angle 
 IDR into two angles of 
 
 n D 
 
 the same size, IDP 
 and RDP. The angle 
 
 of reflection RDP is equal to the angle of incidence 
 IDP. If the angle of incidence was made greater 
 then the angle of reflection would be greater, if 
 the angle of inpidence was made smaller then the 
 angle of reflection would also be made smaller. 
 The reflected ray R and the incident ray / are in 
 the same plane as the perpendicular P. The bril- 
 liancy of reflection is controlled by the quality of 
 the reflecting surface upon which .the light is inci- 
 
REFLECTION FROM A PLANE MIRROR. 51 
 
 dent. Polished surfaces or surfaces light in color 
 reflect with great intensity, whereas rough sur- 
 faces or surfaces dark in color reflect very im- 
 perfectly. 
 
 Reflection from a Plane Mirror. Rays of light 
 are reflected from a plane mirror in the same di- 
 rection in which they fall upon it; if parallel, con- 
 vergent, or divergent before reflection, then they 
 are parallel, convergent or divergent after reflec- 
 tion. An object in front of a plane mirror appears 
 
 FIG. 26. 
 
 just as far back in the mirror as the object is in 
 front of it (Fig. 26). AB represents a plane mirror 
 with EF rays from the extremes of the object / 
 reflected from the mirror AB and meeting at the 
 observer's eye as if they came from the object / 
 in the mirror. The apparent distance of the object 
 7 (as pictured in the mirror) from the observer's 
 eye, is equal to the combined length of the incident 
 and the reflected rays. The appearance of an 
 
52 THE OPHTHALMOSCOPE. 
 
 image in a plane mirror is not exactly the same as 
 that of the object facing the mirror; as it under- 
 goes what is known as lateraMnyersion. This is 
 best understood by holding a printed page in front 
 of a plane mirror, when the words or letters will 
 read from right to left (Fig. 27). 
 
 Spheric Mirrors. A spheric mirror is a portion 
 of a reflecting spheric surface; its center of curva- 
 ture is therefore the center of the sphere of which 
 it is a part. Spheric mirrors are of two kinds, con- 
 cave and convex. 
 
 .- * 
 
 
 
 -f 
 
 
 ~T 
 
 R 
 E F 
 LEG 
 TION 
 
 fl 
 1 3 
 03J 
 HOIT 
 
 FIG. 27. 
 
 Reflection from a Concave Mirror (Fig. 28). 
 All rays of light that pass through the center of 
 curvature to a concave mirror are normals or per- 
 pendiculars at their points of incidence; in other 
 words, these rays of light always travel back and 
 forth on these same lines. With this clearly in 
 mind the reader can at once appreciate the fact that 
 each point on the surface of a curved mirror is 
 equivalent to a plane surface and reflects light ac- 
 
REFLECTION FROM A CONCAVE MIRROR. 53 
 
 cording to the laws of reflection just mentioned. 
 Parallel rays are reflected from a concave mirror j 
 and are brought to a focus in front of it. This 
 focus is called the pmcipal__focus and is always! 
 situated at one-half the distance of the center of] 
 curvature. If the center of curvature is at four 
 inches, then the principal focus or focus for paral- 
 lel rays will be at two inches. If the center of cur- 
 vature is at ten inches, then the principal focus will 
 be at five inches, etc. The ray of light which passes 
 through the center of curvature and the principal 
 focus is called the principal axis. All other rays 
 which pass through the center of curvature are 
 called secondary axes. Rays of light which di- 
 verge from some point between infinity (twenty 
 feet) and the center of curvature will be reflected 
 by a concave mirror and brought to a focus 
 at a point between the principal focus and the 
 center of curvature. The reverse of this state- 
 ment is equally true, i. e., rays of light diverg- 
 ing from a point between the principal focus 
 and the center of curvature will converge at 
 some point between the center of curvature 
 and infinity. In other words, the point from 
 which rays of light diverge and the point to 
 which they converge are conjugate points, or foci. 
 These points are " yoked together." They are in- 
 terchangeable. In Fig. 28 if a point of light was 
 placed at / its rays after reflection would focus at G. 
 It has already been stated that parallel rays al- 
 
54 
 
 THE OPHTHALMOSCOPE. 
 
 ways focus at the principal focus, then if a point of 
 light was placed at the principal focus, its rays after 
 reflection would pass parallel. Rays of light which 
 diverge from a point closer to a concave mirror 
 
 X 
 
 X 
 
 
 FIG. 28. CC, center of curvature ; 2'2 r 2'2', normals or radii of cur- 
 vature. /, PF and i indicate the principal axis. 
 
 than its principal focus, can never meet, as they 
 are reflected still more divergently, but if the eye 
 could intercept them they would be projected back- 
 ward to an imaginary point back of the mirror; 
 this point back of the mirror from which these di- 
 
 FIG. 29. 
 
 vergent rays appeared to come is spoken of as a 
 --virtual or negative focus (VV in Fig. 28). 
 
 Images Formed by a Concave Mirror. To 
 find the position of an image as formed by a 
 
IMAGES FORMED BY A MIRROR. 
 
 55 
 
 concave mirror, two rays may be used to find each 
 individual point of the image: one drawn from a 
 given point in the object to the mirror, parallel to the 
 principal axis and reflected through the principal fo- 
 cus (Fig. 29) ; the other ray must be a secondary 
 axis from the same point, passing through the cen- 
 ter of curvature. The place at which the secondary 
 axis or ray and the reflected ray (or their pro- 
 jections) intersect will give the position of the 
 point in the image which corresponds to the given 
 point in the object. When finding the position of 
 
 FIG. 30. 
 
 an image, if the extreme points are found, then 
 the intermediate points must coincide. Unlike the 
 plane mirror, which produces images at all times 
 and all distances, the concave mirror produces 
 either an erect and virtual image if the object is 
 closer than the principal focus, or a real and in- 
 verted image if the object is placed beyond the 
 principal focus. If an object is at the principal 
 focus, then there will not be any image as the rays 
 would be reflected parallel. Fig. 29 shows an erect, 
 virtual image (ar) of AR which is closer than the 
 
THE OPHTHALMOSCOPE. 
 
 I principal focus. Fig. 30 shows an inverted but 
 real image (ar) of AR which is placed beyond the 
 principal focus. When an object is situated at the 
 center of curvature its image is equally distant and 
 of the same size, but inverted. 
 
 Reflection from a Convex Mirror. All rays are 
 reflected divergently from a convex mirror, and 
 parallel rays diverge as if they came from the 
 principal focus situated behind the mirror at a dis- 
 tance equal to one-half its radius of curvature. 
 
 ( The principal focus of a convex mirror is negative. 
 
 I The foci of convex mirrors are virtual. 
 
 Images Formed by Convex Mirrors. These 
 are always virtual, erect and smaller than the ob- 
 ject. A good illustration of a strong convex mir- 
 ror is the human cornea which the student may 
 
 \ 
 
 C.( 
 
 FIG. 31. 
 
 observe in any patient or in his own eye. The 
 closer the object, the larger the image, and the 
 more distant the object, the smaller the image. In 
 Fig. 31 parallel rays from the object AR are re- 
 flected from the mirror as if they came from the 
 
REFRACTION. 57 
 
 : 
 
 principal focus situated at half the distance of the 
 center of curvature CC. Lines drawn from th 
 extremes of the object to CC are secondary axes, 
 and the image is situated at the point of intersec- 
 tion of the secondary axes and the rays from the 
 principal focus; and as these meet behind the mir- 
 ror the image is smaller than the object, virtual 
 and erect. 
 
 Refraction. From the Latin " refrangere," 
 meaning to " bend back " i. e., to deviate from 
 a straight course. Refraction may be defined as 
 the deviation which takes place in the direction of 
 rays of light as they pass from one medium into 
 another of different density. Or refraction is said 
 to take place when a ray of light passes obliquely 
 from one medium to another and is so bent or devi- 
 ated that its course in the second medium is at an 
 angle with its course in the first medium. 
 
 Two laws govern the refraction of rays of light : 
 
 1. A ray of light passing from a rare into a 
 dense medium is deviated or refracted toward the 
 perpendicular. 
 
 2. A ray of light passing from a dense into a 
 rare medium is deviated or refracted away from 
 the perpendicular. 
 
 A ray of light will continue its straight course 
 through any number of different transparent media, 
 no matter \vhat their respective densities may be, 
 so long as it forms right angles with the surface 
 or surfaces (Fig. 32). Such a ray is spoken of as 
 
THE OPHTHALMOSCOPE. 
 
 the normal or perpendicular; such surfaces are 
 plane, the surfaces and perpendicular forming right 
 angles. Fig. 33 shows the perpendicular (PP) to 
 a piece of plate glass with plane surfaces. The 
 
 
 
 | ICE 
 
 < 
 
 / FLINT GLASS 
 
 I 
 
 > CROWN " 
 
 f 1 
 
 3 PLATE ' 
 
 ^ 
 
 > 
 
 
 FIG. 32. 
 
 ray in air incident at O on the surface SF is bent 
 in the glass toward the perpendicular PP. The 
 dotted line shows the direction the ray would have 
 
 taken had it not been re- 
 fracted. As the ray in the 
 
 F glass comes to the second 
 
 surface at R and passes into 
 a rarer medium it is deviated 
 from the perpendicular PP. 
 The ray now continues its 
 original course ; it has under- 
 9 gone lateral displacement. 
 Prism. A prism is any refracting substance 
 bounded by plane surfaces which intersect each 
 other. The sides of a prism are the inclined sur- 
 faces. The apex is where the two plane surfaces 
 meet. 
 
SPHERIC LENSES. 59 
 
 Prismatic Action. Rays of light which pass 
 through a prism are always refracted toward the 
 base of the prism (Figs. 34 and 35). If an inci- 
 dent ray is perpendicular to one surface of a prism 
 then the second surface alone will refract the ray, 
 
 FIG. 34. FIG. 35. 
 
 but its direction after leaving the prism will be 
 toward the base (Fig. 34). Prisms do not form 
 images. Prisms have no foci. An object viewed 
 through a prism has the appearance of being dis- 
 placed and in a direction opposite to the base, i. e., 
 toward the apex. 
 
 Lenses. There are two kinds of lenses used for 
 refraction purposes spheres and cylinders. 
 
 Spheric Lenses. Abbreviated S. or Sph. 
 Spheric lenses are so named because their curved 
 surfaces are sections of spheres. A spheric lens is 
 one which refracts rays of light equally in all me- 
 ridians or planes. Spheric lenses are of two kinds, 
 convex and concave. 
 
 A convex spheric lens is thick at the centre 
 and thin at the edge (Figs. 36, 37, 38). The fol- 
 lowing are synonymous terms for convex lenses: 
 
6o 
 
 THE OPHTHALMOSCOPE. 
 
 (r) plus, (2) positive, (3) collective, (4) mag- 
 nifying. A convex lens is denoted by the sign 
 of plus ( + ). 
 
 Varieties or kinds of convex lenses: 
 
 A 
 
 FIG. 36. FIG. 37. FIG. 38. 
 
 1. Planoconvex, meaning one surface flat and 
 the other convex. It is a section of a sphere (Fig. 
 36). 
 
 2. Biconvex, also called convexoconvex or bi- 
 spheric, for the reason that it is equal to two plano- 
 convex lenses with their plane surfaces together 
 (Fig. 37). 
 
 3. Concavoconvex. This lens has one surface 
 concave and the other convex, the convex surface 
 having the shorter radius of curvature (Fig. 38). 
 The following are synonymous terms for a con- 
 cavoconvex lens: (i) periscopic, (2) convex men- 
 iscus, (3) converging meniscus (meniscus mean- 
 ing a small moon) (Fig. 38). A periscopic lens 
 enlarges the field of vision, and is of especial service 
 in presbyopia. A periscopic lens is also spoken of 
 as a toric lens. 
 
 A concave spheric lens is thick at the edge and 
 thin at the center (Figs. 39, 40, 41). The follow- 
 
SPHERIC LENSES. 
 
 61 
 
 ing are synonymous terms for a concave lens : ( I ) 
 
 minus, (2) negative, (3) dispersive, (4) minifying. 
 
 A concave lens is denoted by the sign of minus ( ). 
 Varieties or kinds of concave lenses: 
 i. Planoconcave, meaning one surface flat and 
 
 the other concave (Fig. 39). 
 
 7 V7 
 
 A i\ 
 
 FIG. 39. 
 
 FIG. 40. 
 
 FIG. 41. 
 
 2. Biconcave, also called concavoconcave or bi- 
 concave spheric, for the reason that it is equal to 
 two planoconcave lenses with their plane surfaces 
 together (Fig. 40). 
 
 3. Convexoconcave. This lens has one surface 
 convex and the other concave, the concave surface 
 having the shorter radius of curvature (Fig. 41). 
 The following are synonymous terms for a concavo- 
 convex lens: (i) concave meniscus, (2) diverging 
 meniscus, (3) periscopic. 
 
 A spheric lens may be considered as made up 
 of a series of prisms which gradually increase in 
 strength from the center to the periphery, no matter 
 whether the lens be concave or convex. 
 
 In the convex sphere the bases of the prisms are 
 toward the center of the lens, whereas in the con- 
 
62 
 
 THE OPHTHALMOSCOPE. 
 
 cave the bases of the prisms are toward the edge 
 (Figs. 42, 43). 
 
 FIG. 42. 
 
 Knowing that a prism refracts rays of light 
 toward its base, it may be stated as a rule that 
 every lens bends rays of light more sharply as the 
 
 FIG. 43. 
 
 periphery is approached, i. e., at the periphery the 
 strongest prismatic effect takes place. 
 
 Parallel rays of light passing through a convex 
 
CONJUGATE FOCI. 63 
 
 lens come together at a point called the principal 
 focus (Fig. 44). This principal focus is also known 
 as the shortest focus. Parallel rays of light passing 
 through a concave lens diverge, as if they came 
 from a point on the same side of the lens as the 
 parallel rays, and this point is known as the princi- 
 pal focus of the concave lens (Fig. 45). 
 
 FIG. 44. 
 
 The action of a convex lens is similar to that of 
 a concave mirror, and the action of a concave lens 
 is similar to that of a convex mirror. 
 
 P.P. 
 
 FIG. 45. 
 
 Conjugate Foci. Lenses like mirrors have con- 
 jugate foci, conjugate meaning " yoked together." 
 The point from which rays of light diverge and the 
 point to which they converge are conjugate foci or 
 points; for instance in Fig. 46 the rays diverging 
 
64 THE OPHTHALMOSCOPE. 
 
 from A and passing through the lens converge to 
 the point B, then the points A and B are conjugate 
 foci. They are interchangeable, for if rays diverge 
 from B they will follow the same path back 
 again and meet at A. The path of the ray 
 
 FIG. 46. 
 
 CC' is the same whether it passes from A .to 
 B or from B to A there is no difference. It is by 
 the affinity of these points for each other, with re- 
 spect to their positions, that they are called con- 
 jugate. The equivalent to conjugate foci is found 
 in the long or myopic eye, an eye in other words, 
 which has its fovea situated further back than the 
 principal focus of its dioptric media, the result be- 
 ing that rays of light from the fovea of such an 
 eye will be projected convergently after passing out 
 of the eye and will meet at some point inside of 
 infinity (twenty feet). The fovea of a myopic 
 eye represents a conjugate focus. A myopic eye 
 is in a condition to receive divergent rays of light 
 at a focus on its retina and to ^grnit convergent 
 rays. 
 
 Ordinary Foci. When rays of light diverge 
 from some point inside of infinity and beyond the 
 principal focus, they will be brought to a focus at 
 some point on the other side of a convex lens beyond 
 
ORDINARY FOCI. 
 
 its principal focus; this point is called a conjugate 
 or ordinary focus. A lens may have many foci 
 but only two principal foci. When rays of light, 
 diverge from some point closer to a lens than its 
 
 FIG. 47. 
 
 principal focus, they do not converge but after re- 
 fraction continue divergently, their focus now be- 
 ing found by projecting these divergent rays back 
 to a point on the same side of the lens from which 
 they appear to come; this point is called negative 
 or virtual (Fig. 47). This is equivalent to what 
 takespace in a short or hypermetropic eye, an 
 eye which has its macula closer to its dioptric 
 media than its principal focus. In a state of rest 
 the fovea of such an eye would project divergent 
 
 FIG. 48. 
 
 rays outward and would be in a position to receive 
 only convergent rays of light at a focus upon its 
 fovea. 
 7 
 
66 
 
 THE OPHTHALMOSCOPE. 
 
 Images Formed by Lenses. An image formed 
 by a lens is composed of foci, each one of which 
 corresponds to a point in the object. Images are 
 of two kinds, real and virtual. 
 
 A Real Image. This is an image formed by 
 the actual meeting of rays of light; such images 
 can always be projected onto a screen (Fig. 48). 
 
 FIG. 49. 
 
 A Virtual Image. This is one that is formed 
 by the prolongation backwards of rays of light to 
 a point. Such images cannot be projected onto a 
 screen; such images can only be seen by looking 
 through the lens. 
 
 .A' 
 
 FIG. 50. 
 
 Fig. 49 shows the arrow AB closer to the bi- 
 convex lens than its principal focus. An eye look- 
 ing through this lens at the arrow would see a 
 virtual, erect and magnified image of the arrow at 
 
NUMERATION OF LENSES. 67 
 
 A'B'. Fig. 50, however, shows the arrow AR in 
 front of a concave lens and the eye looking through 
 this lens sees a virtual, erect and minified image of 
 the arrow at A'R'. 
 
 Numeration of Lenses. Formerly lenses were 
 numbered by the distance of the principal focus 
 from the center of the lens, as measured in English 
 inches, one inch being 25.4 millimeters. The unit 
 known as i, was a lens that would focus rays of 
 light at the distance of one inch. Half the unit 
 was written l /2 and was called the half inch, but 
 this means that the lens is one-half the strength 
 of the unit, and therefore focuses at twice the dis- 
 tance of the unit, viz., at two inches, and so the 
 old nomenclature numbered its lenses in fractions, 
 the denominator of the fraction signifying the prin- 
 cipal focal distance in inches. 
 
 The present system of numbering lenses is by 
 the diopter system, abbreviated D. The unit of 
 this system is a lens that will form a principal focus 
 at 40 inches (39.37 English inches). The strength 
 or refractive power of a dioptric lens is therefore 
 the inverse of its focal distance. The shorter the 
 focal distance the stronger the lens. To find the 
 focal distance of any dioptric lens in inches or cen- 
 timeters the number of diopters expressed must be 
 divided into the unit of 40 inches, or 100 centi- 
 meters; for example, a 2 D. lens has a focal dis- 
 tance of 40 divided by 2, equals 20 inches, or 100 
 centimeters divided by 2 equals 50 centimeters. 
 
68 
 
 THE OPHTHALMOSCOPE. 
 
 Lenses that have a refractive power less than a 
 unit are not expressed in the form of fractions, but 
 in the form of decimals : for example, a lens which 
 is only one-fourth, one-half or three-fourths the 
 strength of the unit is written 0.25, 0.50, 0.75, re- 
 spectively. 
 
 To change the old nomenclature or inch system 
 of numbering lenses into diopters, divide the unit 
 (40 inches) by the denominator of the fraction, 
 and the result will be an approximation in diopters ; 
 for example, i/io equals 40/10, or 4 D. ; 1/20 
 equals 40/20, or 2 D. 
 
 Cylindric Lens. Abbreviated C, c or Cyl. A 
 cylinder lens receives its name from being a seg- 
 ment of a hollow or solid cylinder parallel to its 
 
 FIG. 51. 
 
 FIG. 52. 
 
 axis (Figs. 51 and 52). A cylinder is a lens which 
 refracts rays of light in one meridian only and 
 that meridian is always opposite to its axis. A 
 cylinder lens has no one common focus or focal 
 point, but a line of foci which is parallel to its axis 
 
CYLINDRIC LENSES. 
 
 6 9 
 
 (Fig. 53). The dimension of a cylinder lens which 
 is parallel to the axis of the original cylinder, of 
 which it is a part, is spoken of as the axis and is 
 indicated on the lens by a short diamond scratch 
 at its periphery, or by having a small portion of 
 its surface corresponding to the axis ground at 
 
 FIG. 53- 
 
 the edges, or it may be marked in both ways (Fig. 
 54). Cylinders are of two kinds, convex and con- 
 cave. A convex cylinder converges parallel rays 
 
 FIG. 54. 
 
 of light so that they are brought into a straight line 
 which corresponds to the axis of the cylinder (Fig. 
 53). A concave cylinder diverges rays of light 
 opposite to its axis as if they had diverged from 
 
THE OPHTHALMOSCOPE. 
 
 a straight line on the opposite side of the lens (Fig. 
 55). 
 
 FIG. 55- 
 
 Spherocylinders. A spherocylinder is a com- 
 bination of a sphere and a cylinder, and is there- 
 fore a lens which may have one surface ground 
 with a spheric curve and the other surface cylin- 
 dric. Spherocylinders therefore have two differ- 
 ent curves. The spheric curve may be convex 
 with the cylinder surface convex, or the spheric 
 surface may be concave with the cylinder surface 
 concave, or the spheric surface may be convex 
 with the cylinder surface concave, or the spheric 
 surface may be concave with the cylinder surface 
 convex, or, as in the toric spherocylinder, or two 
 cylinders of different strengths may be ground on 
 one surface and a sphere on the other surface. 
 
 As a plus sphere 
 will bring parallel 
 rays of light to a fo- 
 cus, then such a lens 
 (of proper strength) 
 if placed in front of 
 a hypermetropic eye 
 (Fig. 56) will increase the refraction of such an eye 
 
 FIG. 56. 
 
SPHEROCYLINDERS. 
 
 and bring parallel rays of light to a focus on the 
 retina (Fig. 57), making the eye equivalent to what 
 is known as the standard or emmetropic eye (Fig. 
 58). The emmetropic eye is an eye therefore that 
 
 FIG. 57. 
 
 FIG. 58. 
 
 does not require any lens to make parallel rays 
 focus upon its retina. 
 
 As a minus sphere will diverge parallel rays of 
 light, then such a lens (of proper strength) if 
 placed in front of a myopic eye (Fig. 59) will give 
 parallel rays such an amount of divergence, that 
 when they enter the myopic eye they will focus on 
 
 FIG. 59. 
 
 its retina (Fig. 60), making it equivalent to the 
 emmetropic eye. 
 
 Astigmatism is the condition of an eye in which 
 parallel rays of light are not refracted equally in 
 all meridians, one meridian refracting stronger 
 
72 THE OPHTHALMOSCOPE. 
 
 than the meridian at right angles, hence the use of 
 a cylinder lens which refracts rays in one meridian 
 only, and therefore diminishes or weakens the 
 stronger meridian in myopia ( cylinder) and in- 
 creases or strengthens the refraction in the weaker 
 meridian in hypermetropia (+ cylinder). 
 
 FIG. 60. 
 
 Estimating the Refraction of an Eye with 
 the Direct Method. For a close approximation 
 of the patient's refraction, the following essentials 
 should have very careful attention. The observer 
 should wear his own correcting glasses or make 
 due allowance for his error when reading the 
 findings at the sight-hole of the ophthalmoscope. 
 The observer must relax his accommodation, and 
 if possible the patient's accommodation should be 
 at rest with a reliable cycloplegic (atropin). The 
 use of " drops " is not so important in the aged. 
 The ophthalmoscope must be held close to the ob- 
 server's and patient's eye. With these matters 
 carefully executed, then the following statement 
 of facts will be correct. 
 
 Emmetropia. Seeing the fundus distinctly 
 without any lens at the sight-hole of the ophthal- 
 
MYOPIA. /3 
 
 moscope, means that parallel rays are emerging 
 from the eye under observation, then passing 
 through the sight-hole of the instrument enter the 
 observer's eye and focus on his macula. 
 
 Hypermetropia. If a plus sphere must be used 
 at the sight-hole of the ophthalmoscope to see the 
 eye ground distinctly, then the eye must be hyper- 
 metropic and the amount of the hypermetropia is 
 represented by the strongest plus glass so employed. 
 The rays of light leaving the hypermetropic eye 
 divergently (Fig. 56) cannot focus on the ob- 
 server's retina without the aid of the plus glass, 
 or unless the observer is myopic ; or accommodates, 
 which he must learn not to do. 
 
 Myopia. If a minus sphere is used at the sight- 
 hole of the ophthalmoscope to give a clear view 
 of the fundus, which was otherwise indistinct, then 
 the eye under observation must be myopic and the 
 amount of the myopia is represented by the strength 
 of the weakest minus sphere so employed. The 
 rays of light leaving the myopic eye convergently 
 cannot focus on the observer's retina without the 
 aid of the minus sphere. If the observer had been 
 myopic two diopters and did not wear his glasses 
 and the eye under observation was also myopic 
 of the same amount, then the lens at the sight-hole 
 of the ophthalmoscope would have been minus four, 
 the amount of the observer's and the patient's error. 
 The same statement of facts would hold true if 
 they had each been hypermetropic, then the plus 
 8 
 
74 THE OPHTHALMOSCOPE. 
 
 sphere at the sight-hole of the ophthalmoscope 
 would have recorded both errors. If the observer 
 does not wish to wear his refractive error, then he 
 must deduct the amount of his error from the 
 strength of the lens with which he sees the pa- 
 tient's eye ground distinctly. 
 
 Astigmatism. To estimate correctly the refrac- 
 tion of an astigmatic eye with the ophthalmoscope 
 is not an easy matter for the simple reason that the 
 observer cannot always relax his accommodation, 
 and furthermore the examination is limited princi- 
 pally to focusing the retinal vessels in different 
 meridians and these vessels do not always appear 
 at convenient places for this purpose. Astigmatism 
 is the condition of an eye in which there are two 
 principal meridians of different refracting power, 
 and these are usually at right angles to each other. 
 The observer with the ophthalmoscope must select 
 these two chief meridians for his observations. It is 
 impossible to estimate the refraction at the macula 
 as there are no vessels visible at this point, there- 
 fore the examinations are usually made with ves- 
 sels at or near the disc. The observer focuses a 
 selected vessel with the weakest minus or strongest 
 plus glass with which he can see it and makes a note 
 of its direction and then focuses another vessel (in 
 the same manner) as near a right angle position to 
 the first vessel as possible. The difference in 
 strength of these two lenses is the amount of the 
 astigmatism and represents the strength of the 
 
ASTIGMATISM. 75 
 
 f cylinder lens necessary for its correction. The 
 observer must remember when making estimates 
 for astigmatic errors that when he sees a vessel 
 distinctly he is viewing it through the meridian op- 
 posite to its course, i. e., if the vessel is at axis ninety 
 he is seeing it through the horizontal meridian, if 
 the vessel is at axis one hundred and eighty he is 
 seeing it through the vertical meridian, etc. 
 
 Simple Hypermetropic Astigmatism. With 
 the formula -f 3.00 cyl. axis 90 degrees, the oph- 
 thalmoscope would reveal the horizontal vessels seen 
 without any glass, emmetropic, and the vertical ves- 
 sels with a plus three at the sight-hole. 
 
 Simple Myopic Astigmatism. With the for- 
 mula --2.00 cyl. axis 180 degrees, the ophthal- 
 moscope would reveal the vertical vessels without 
 any lens at the sight-hole (emmetropic) and the 
 horizontal vessels seen with a minus two. 
 
 Compound Hypermetropic Astigmatism. With 
 formula -f- 2.00 sph. C + i.oo cyl. axis 90 degrees. 
 Vertical vessels will be seen distinctly with + 3 and 
 the horizontal vessels with a + 2. The difference 
 between the chief meridians is + I, which is the 
 cylinder with its axis at 90 degrees and the + 2 
 would be the amount of the additional refraction 
 for all meridians. 
 
 Compound Myopic Astigmatism. With a for- 
 mula -- i.oo sph. C 3.00 cyl. axis 180 degrees, 
 the vertical vessels will be seen with - - i and 
 the horizontal vessels with - 4. The differ- 
 
7 6 THE OPHTHALMOSCOPE. 
 
 ence between the two meridians would be -- 3.00 
 cyl. at axis 180 degrees. The --i would be the 
 amount of the additional myopia for all meridians. 
 
 Mixed Astigmatism. With the formula 2.00 
 sph. C + 5.00 cyl. axis 90 degrees, the vertical ves- 
 sels would be seen with a + 3.00 and the horizontal 
 vessels with 2.00. 
 
 Retinoscopy. This is a method of estimating 
 the refraction of an eye without viewing the details 
 of the fundus as in the direct method, and the ob- 
 server does not have to make any note of his ac- 
 commodation, although the patient's accommoda- 
 tion should be relaxed and his pupil widely dilated. 
 The observer may sit at any distance in front of 
 the patient, preferably at 40 inches, and reflect the 
 light into the patient's eye from the concave mirror 
 of the ophthalmoscope, or he may use a plane mirror 
 held in front of his eye. Gently rotating the mirror 
 as the patient looks towards the observer's fore- 
 head, the illumination seen in the patient's pupil will 
 appear to be stationary, not to move, or it will ap- 
 pear to move as the mirror is moved or it will ap- 
 pear to move in the opposite direction to that in 
 which the mirror is rotated, depending upon the 
 kind of mirror employed and the variety of the re- 
 fractive error. 
 
 Retinoscopy practiced with the plane mirror at 
 40 inches : 
 
 i. The faster the illumination appears to move 
 the weaker the refractive error. 
 
RETINOSCOPY. 77 
 
 2. The slower the illumination appears to move 
 the stronger the refractive error. 
 
 3. The illumination appearing to be stationary 
 as the mirror is rotated, the refractive error will 
 be myopic i D. 
 
 4. The illumination appearing to move opposite 
 to the movement of the mirror, the refraction will 
 be myopic more than i D. 
 
 5. The illumination moving with the movement 
 of the mirror after a + i D. has been placed in 
 front of the eye means that the eye is hypermetropic. 
 
 6. The illumination appearing to move faster 
 in one meridian than another (usually the meridian 
 at right angles) signifies astigmatism. 
 
 7. When the illumination appears as a band of 
 light extending across the pupil, then the eye is as- 
 tigmatic. 
 
 Retinoscopy practiced with the concave mirror at 
 40 inches: 
 
 1. The apparent fast or slow rate of movement 
 of the illumination signifies respectively a weak or 
 strong refractive error. 
 
 2. No apparent movement signifies myopia of 
 i D. 
 
 3. The illumination appearing to move with the 
 mirror signifies myopia of more than i D. 
 
 4. The illumination appearing to move opposite 
 to the movement of the mirror while a + i D. is 
 in front of the eye signifies hypermetropia. 
 
78 THE OPHTHALMOSCOPE. 
 
 5. The statements under 6 and 7 for the plane 
 mirror are equally true for the concave mirror. 
 Retinoscopy is certainly the simplest, most exact 
 and the easiest method to learn to estimate the re- 
 fraction. 
 
CHAPTER III. 
 
 ANATOMY AND ANOMALIES OF THE EYE. 
 
 THE human eye is shaped like a sphere except 
 that it has a constriction on its anterior portion cor- 
 responding to the base of the cornea. The antero- 
 posterior diameter of the standard eye is 24.3 milli- 
 meters, transversely it is 23.6 millimeters, and 
 vertically 23.4 millimeters. The eyeball consists 
 of three tunics or coats, and within are two humors, 
 aqueous and vitreous, having the crystalline lens 
 between them (Fig. 61). 
 
 The tunics from without inward are: 
 
 1. The sclera and cornea. 
 
 2. The choroid, iris, and ciliary body. 
 
 3. The retina. 
 
 The media are the cornea, aqueous humor, crys- 
 talline lens and vitreous humor. 
 
 The aqueous humor occupies the corneal cavity 
 and lies in front of the lens while the vitreous 
 humor fills the cavity of the sclera, posterior to 
 the lens. 
 
 The Sclera (o-K\rjp6<s, "hard") or sclerotic coat 
 (c, Fig. 61) is thickest posteriorly (one millimeter) 
 and diminishes in thickness anteriorly (0.4 milli- 
 meter), where it is reinforced by the tendons of 
 the muscles. The sclera consists of bundles of fine 
 
 79 
 
8o 
 
 THE OPHTHALMOSCOPE. 
 
 f 
 
 FIG. 61. HORIZONTAL SECTION OF THE RIGHT EYE. (Landois.) 
 a, Cornea ; b, conjunctiva ; c, sclerotic ; d, anterior chamber contain- 
 ing the aqueous humor ; e, iris ; //', pupil ; g, posterior chamber ; /, 
 Petit's canal ; j, ciliary muscle ; k, corneoscleral limit ; f, canal of 
 Schlemm ; m, choroid ; n, retina ; o, vitreous humor ; No, optic nerve ; 
 q, nerve-sheaths ; p, nerve-fibers ; Ic, lamina cribrosa ; h, crystalline 
 lens ; or, ora serrata ; pc, ciliary processes ; the line, OA, indicates the 
 optic axis ; Sr, the axis of vision ; r, the position of the fovea centralis ; 
 Kn, nodal point ; x, equator of lens ; t, external rectus muscle ; s, inter- 
 nal rectus muscle ; Z, optic nerve-sheath ; H, sclerotic. 
 
THE CORNEA. 8 I 
 
 fibrillse of connective tissue which form in circles, 
 some corresponding to the equator and others run- 
 ning meridionally. The sclera, pearly white in 
 color, contains in its deeper portion some pig- 
 ment cells. While the sclera has very few vessels 
 of its own, yet it is traversed by vessels and nerves 
 which pass into the interior of the eye. The scleral 
 coat is anatomically a continuation of the sheath 
 of the optic nerve, which sheath is itself continuous 
 with the dura mater. The sclera, by virtue of its 
 thickness, toughness, and hardness, assists in giv- 
 ing the eyeball its shape, and is a protection to 
 the structures within. Posteriorly, and about 10 
 degrees to the nasal side of the center, the sclera 
 contains an opening (about two millimeters in di- 
 ameter) called the scleral opening (foramen 
 sclerae) for the entrance of the optic nerve fibers. 
 The scleral coat is also perforated by the venae 
 vorticosae and by the posterior and anterior ciliary 
 arteries and nerves. 
 
 The Cornea. (/ce/>a9, horn) (a, Fig. 61). This 
 structure together with the sclera, forms the outer 
 fibrous tunic or coat of the eye. The cornea in 
 health represents a section of a transparent sphere 
 with a radius of curvature, normally of 7.8 milli- 
 meters on its anterior surface. The posterior 
 radius of curvature is about 7.^ millimeters. These 
 normal radii are seldom found as most eyes have 
 corneal astigmatism. The diameter of the base of 
 the cornea is about 12 millimeters horizontally, and 
 
82 THE OPHTHALMOSCOPE. 
 
 1 1 millimeters vertically, as the scleral tissue over- 
 laps the cornea on its upper and lower edges. As 
 the diameter of the eyeball itself is 24 millimeters 
 (radius 12 millimeters), then the cornea with its 
 shorter radius must adjust itself to the sclera as a 
 watch crystal on a watch. This can be seen with 
 a magnifying glass by close observation of any 
 healthy eye, as the white sclera is then seen to ex- 
 tend over onto the transparent cornea ; this is usu- 
 ally more conspicuous above and below, giving the 
 cornea the appearance of a horizontal ellipse. The 
 cornea is thicker at its edge than at its center. As 
 just stated, the cornea and sclera are very similar 
 in their anatomic construction and are continuous 
 structures, though one is transparent and the other 
 is not; the cornea has a different arrangement of 
 its fibrous network and the character of its cells is 
 different from the sclera also. 
 
 The cornea is made up of the following layers: 
 
 1. The Anterior- Epithelium. This consists of 
 several layers of pavement epithelium, the super- 
 ficial are flattened, the deep cells are cylindrical and 
 between these layers the cells are more or less 
 rounded. This epithelial layer is virtually a con- 
 tinuation of the conjunctiva and is sometimes 
 spoken of as the conjunctiva of the cornea. 
 
 2. Bowman's Membrane, also called the anterior 
 elastic membrane. This thin homogeneous mem- 
 brane lies beneath the epithelium; it is firmly at- 
 
VESSELS. 83 
 
 tached to the underlying stroma and is a part of the 
 cornea proper. 
 
 3. The Stroma or Cornea Proper (Substantia 
 Propria). This represents the major portion of 
 the cornea and is continuous with the sclera. It 
 contains, or is made up of, bundles of fibers of 
 connective tissue arranged in lamellae. Between 
 these lamellae are spaces containing lymph, hence 
 they are called lymph spaces, and are connected with 
 each other by narrow openings called canals. Nor- 
 mally the cornea does not contain blood vessels. 
 
 4. Descemet's Membrane. Posterior-elastic 
 membrane. As Bowman's membrane forms the 
 anterior portion of the cornea proper, so Desce- 
 met's membrane forms the posterior, and while 
 Bowman's is quite intimately adherent to the 
 stroma, yet Descemet's membrane is not so. This 
 latter is very dense or tough and by virtue of its 
 toughness it is a protection for the eye against 
 penetrating diseases of the cornea. Descemet's 
 membrane may be considered as a part of the uvea 
 or inner tunic of the eye. 
 
 5. The fifth layer of the cornea, known as the 
 posterior pavement or endothelial layer, .is but a 
 single layer of cells more or less flattened, and 
 these cells, like Descemet's membrane, are a part 
 of the uvea, and with Descemet's membrane pre- 
 vent the aqueous fluid from passing into the stroma. 
 
 Vessels. The cornea in health is non-vascular. 
 It receives its nutrition from the anterior ciliary 
 
84 THE OPHTHALMOSCOPE. 
 
 vessels which form a network of loops at the mar- 
 gin (limbus) of the cornea. Plasma passes from 
 the loops of the vessels into the lymph spaces 
 or canals in the cornea, and in this way the cor- 
 nea is nourished. 
 
 Nerves. The epithelial cells, Bowman's mem- 
 brane and anterior lamellae of the cornea proper, 
 contain numerous fine nerves, branches from the 
 long ciliary and nerves of the ocular conjunctiva. 
 Minute branches perforate Bowman's membrane 
 from the stroma and pass freely to the epithelial 
 layer. This network of nerves acts as a protec- 
 tion to the cornea, by giving it extreme sensibility 
 to all external injurious influences. The cornea 
 being transparent, and a section of a small sphere, 
 refracts the rays of light as they enter the eye and 
 with the assistance of the crystalline lens brings 
 parallel rays to a focus at the macula in a standard 
 eye. In fact, the cornea is the most important re- 
 fractive media of the eye. 
 
 The middle tunic of the eye consists of the 
 choroid, iris and ciliary body (commonly called 
 the uveal tract). 
 
 The Choroid. (xopioeiS^s ; Latin " corium," 
 skin) (m, Fig. 61). The choroid is known as the 
 vascular coat, is brown in color and lies between 
 the sclera and the retina, and extends from the 
 edge of the optic nerve posteriorly w 7 here it is 0.16 
 millimeter in thickness, to the ora serrata (or. Fig. 
 6 1 ) anteriorly, where it is 0.08 millimeter in thick- 
 
THE CHOROID. 85 
 
 ness. It has a few attachments to the sclera by the 
 lamina fusca. Posteriorly it is perforated by a 
 round opening known as the foramen choroid, 
 through which pass the optic nerve fibers and ves- 
 sels. The choroid has two principal attachments; 
 at the margin of the optic nerve entrance (the 
 region of the posterior ciliary arteries) and at the 
 equator of the eye, where most of the venous blood 
 passes out of the eye (venae vorticosse). Anatomic- 
 ally the choroid is made up of five layers. 
 
 1. Externally and next to the sclera a layer 
 known as the suprachoroid, which is rich in pig- 
 ment. 
 
 2. The inner layer, lamina vitrea, not pigmented, 
 lies next to the retina. Between the suprachoroid 
 and the lamina vitria are three layers of vessels; 
 from without inward these are: (a) the layer of 
 large vessels, (b) the layer of medium sized ves- 
 sels, (c) the layer of capillaries (chorio-capillaris). 
 
 The layer of large vessels is made up mostly of 
 large veins which lie very close together and anas- 
 tomose freely; the spaces between the vessels are 
 filled more or less with pigment cells. The 
 amount of pigment varies in different eyes, being 
 abundant in mulattoes and brunettes, and much 
 less so in blondes and possibly entirely absent in 
 albinos. 
 
 The layer of medium size vessels is not as thick 
 as the layer of large vessels and is not as heavily 
 pigmented. The capillary layer, as its name implies, 
 
86 THE OPHTHALMOSCOPE. 
 
 is made up of capillaries, but of large caliber and 
 yet without pigrnented interspaces. The choroidal 
 circulation and choroidal pigment influence greatly 
 the color of the fundus reflex described in Chapter 
 IV. The pigment cells of the choroid are branched 
 and anastomosing. The choroid is not supplied 
 with sensory nerves. The posterior ciliary arteries 
 supply most of the blood to the choroid. The veins 
 of the choroid run nearly parallel to each other, 
 but finally converge into six or eight large trunks 
 (veriae^voxtieosje) and pierce the sclera obliquely 
 near the equator, and carry the blood from the 
 choroid. 
 
 The short ciliary arteries are the chief supply 
 of the choroid, and they number four or six small 
 vessels or branches from the ophthalmic artery. 
 These break up into about twenty branches, pierc- 
 ing the sclerotic around the optic nerve. The 
 function of the choroid by virtue of its great vas- 
 cularity is to nourish the retina, vitreous and lens 
 and to furnish the visual purple, and by its pigmen- 
 tation to make the interior of the eye a dark cham- 
 ber or camera. 
 
 The Iris (rainbow-shaped). This forms the 
 anterior portion of the uveal tract and is described 
 as a membranous curtain, disc-shaped and per- 
 forated slightly to the nasal side of its center by 
 a round opening called the pupil; this opening is 
 normally about 3^2 millimeters in diameter. The 
 diameter of the iris is about n millimeters and at 
 
THE IRIS. 87 
 
 its margin is attached to the ciliary body, of which 
 it is anatomically a part. Normally the pupillary 
 margin of the iris is always in contact with the 
 anterior capsule of the lens, whether the pupil be 
 dilated or contracted. The aqueous humor lies 
 posterior to the cornea and anterior to the lens. 
 The iris divides the aqueous humor into two parts, 
 known as the anterior and posterior chambers, and 
 these two chambers are in communication through 
 the pupil. Anatomically, the iris is made up of 
 blood vessels and a fibrous connective tissue, to- 
 gether with the pigment cells and the sphincter of 
 the iris. The endothelial lining membrane of the 
 cornea and Descemet's membrane are continuous 
 onto the anterior surface of the iris up to its 
 pupillary margin; this covering of endothelial 
 cells is not complete on the iris for at various points 
 it is missing, and at these points there are depres- 
 sions in the iris stroma called crypts. The posterior 
 surface of the iris is lined with pigment called the 
 retinal pigment, and this continues well forward 
 into the pupillary edge of the iris, where it becomes 
 quite conspicuous in some eyes and in some dis- 
 eases of the iris and occasionally with cataract. 
 Lying next to the retinal pigment of the iris is the 
 dilator of the pupil; this is not muscular tissue but 
 an elastic tissue made up of fibers extending radi- 
 ally from the pupillary edge of the iris to its 
 periphery. Close to the pupillary edge of the iris, 
 and within the iris stroma is found the sphincter 
 
THE OPHTHALMOSCOPE. 
 
 of the iris; this is muscular tissue, flat and about 
 one millimeter in width. Viewing the iris on its 
 anterior surface it is found to be uneven or filled 
 with ridges, elevations and depressions, and at its 
 periphery are seen concentric circles; these latter 
 are the folds made by the iris when the pupil dilates. 
 The ridges are formed by blood vessels. The iris 
 pigment is of two kinds, one the pigment in the iris 
 stroma, and the other, the retinal pigment layer. 
 The color of the iris is controlled in great part by 
 the amount of its pigment. The pigment in the 
 retinal layer is always quite abundant, whereas that 
 in the stroma varies considerably. If the stroma 
 does not contain any pigment or only a small 
 amount, then the retinal pigment layer shows 
 through the stroma, giving the iris a blue color. 
 The gray iris is seen when the stroma, free from 
 pigment, is quite thick. The dark iris (brown, 
 hazel, etc.) means that the stroma contains pig- 
 ment. Blondes usually have light-colored irises and 
 mulattoes or brunettes dark-colored irises, show- 
 ing that usually the pigmentation of the iris is 
 consistent with the eye ground and body pigmen- 
 tation. 
 
 Arteries. The long posterior ciliary and the 
 anterior ciliary, and branches of the muscular 
 arteries supply the iris with blood, forming a large 
 circle at the periphery of the iris and a small circle 
 near the pupillary margin. Many arteries pass 
 radially from the periphery to the pupillary edge 
 
CILIARY BODY. 89 
 
 of the iris. The direction of these vessels has al- 
 ready been incidentally referred to in the descrip- 
 tion of the iris. 
 
 Nerves. The iris is supplied by a motor branch 
 from the third pair of nerves, and with sympathetic 
 fibers from the ciliary^ganglion. The iris does not 
 contain ganglion cells. The function of the iris is 
 to control the amount of light entering the eye. 
 
 Ciliary Body (cilia, " lashes," and so-called 
 from radiating folds seen on the surface of the 
 ciliary body) (/, Fig. 61 ) . Also from KVK\OS, mean- 
 ing a circle. The ciliary body in section is triangu- 
 lar in shape, the base of the triangle being shorter 
 than the sides, which are about 3 millimeters in 
 length. The ciliary body lies beneath the sclera and 
 just back of its junction with the cornea. A width 
 of sclera about 4 millimeters, extending back from 
 the edge of the cornea, covers the ciliary body ; this 
 width is called the pericorneal or dajigejv^one. The 
 outer side of the ciliary body, that next to the sclera, 
 is formed by the ciliary muscle and the inner side 
 is formed by the ciliary processes. The base of the 
 triangle faces forward toward the cornea and at 
 its center gives attachment or origin to the iris. 
 Near the apex of this triangular body, on its inner 
 surface, are the ciliary processes, about seventy in 
 number, and lighter in color than the rest of the 
 ciliary body, which appears black. The ciliary body 
 is attached to the scleral corneal junction by the 
 ligamentum pectinatum. In the ciliary body next 
 9 
 
9O THE OPHTHALMOSCOPE. 
 
 to the sclera is found the ciliary muscle with its 
 many layers of muscular fibers. The longitudinal 
 or meridional fibers, known as the tensor choroidise, 
 or muscle of Briicke pass backward to be inserted 
 into the external layers of the choroid. Lying 
 beneath the tensor choroidiae fibers and crossing 
 them here and there are found the circular or 
 sphincter fibers, the muscle of Miiller. This is 
 called the compressor lentis. Many other muscular 
 fibers are also found in the ciliary body, but the 
 two just mentioned are the principal ones considered 
 in the act of accommodation. The ciliary processes 
 are covered and filled in with pigment and contain 
 r a great number of blood vessels. The ciliary body 
 is supplied by the posterior and anterior ciliary 
 arteries. Some of the veins of the ciliary body and 
 all of those of the iris empty eventually into the 
 vena vorticosse, while a few of the veins from the 
 ciliary muscle pass out through the sclera. The 
 nerves of the ciliary body, besides motor branches, 
 are many sensory branches from the trigeminus. 
 
 Uvea and Uveal Tract. If the sclera and cor- 
 nea and optic nerve can be removed from an eye, 
 then the remaining choroid, ciliary body and iris 
 being exposed show the pupillary opening anteri- 
 orly, and the opening for the optic nerve posteriorly. 
 These three structures, on account of their dark 
 color, somewhat resemble a grape (uvea), hence 
 called the uvea or uveal tract. 
 
 The Retina. (Reta, net) (n, Fig. 61). This 
 
THE RETINA. 9 1 
 
 is the inner tunic or coat of the eye, the end organ 
 of the optic nerve. In health the retina is a trans- 
 parent membrane and is held in contact with the 
 choroid by the vitreous humor. The retina is at- 
 tached at the optic nerve posteriorly and at the ora 
 serrata anteriorly ; also at the f ovea centralis, where 
 it adheres slightly to the choroid. The optic nerve 
 fibers spread out in all directions from the disc and 
 pass through the layers of the retina, having their 
 terminal endings, the rods and cones, at the exter- 
 nal surface of the retina. The retina may be sub- 
 divided into ten layers, but the principal tissues of 
 which the retina is composed are the nervous and 
 supporting. The ten layers of the retina are : 
 
 1. Pigment layer. 
 
 2. Layer of rods and cones. 
 
 3. Membrana limitans externa. 
 
 4. Outer granular layer. 
 
 5. Fiber layer of Henle. 
 
 6. Outer reticular layer. 
 
 7. Inner granular layer. 
 
 8. Inner reticular layer. 
 
 9. Ganglion-cells layer. 
 10. Nerve fiber layer. 
 
 As the sclera is considered a continuation of 
 the dura mater, so the nerve fiber layer of the 
 retina may be considered an expansion of the brain. 
 The part of the retina corresponding to the optic \ 
 nerve entrance is known as the disc, or nerve head, I 
 or papilla. 
 
92 THE OPHTHALMOSCOPE. 
 
 Pigment Layer of the Retina. This is called 
 the tenth layer of the retina, and lies next to the 
 choroid. It is a most important layer or part of the 
 retina as it is a guide to the observer with the 
 ophthalmoscope, and suggests the separation or 
 line of demarkation between the retinal and cho- 
 roidal structures during any inflammation affecting 
 either one. The pigment consists of six-sided cells 
 and in a single layer; the cells are separated by a 
 clear or transparent space, and each cell is pig- 
 mented to only one-half its thickness (1/500 of a 
 line) ; the cell itself is therefore 1/250 of a line in 
 thickness. This is important to know and appre- 
 ciate, as it explains the coloring of the fundus re- 
 flex as coming from the choroid and not from the 
 retina, this pigmentation not being sufficient in it- 
 self to entirely conceal the choroidal reflex. 
 
 The Lens, also called crystalline body. Nor- 
 mally the lens is without color and transparent, bi- 
 convex in shape, with a longer radius on the an- 
 terior than on the posterior surface, the former 
 being about 10 and the latter 6 millimeters. The 
 lens is held in place by its own ligament (liga- 
 mentum suspensorium lentis, or zonula of Zinn). 
 The edge or equator of the lens is about .5 milli- 
 meter from the ciliary processes. At rest the lens 
 is 8.7 millimeters in its equatorial diameter, and 3.6 
 millimeters in its anteroposterior diameter on its 
 axis, from pole to pole. The center of the lens is 
 called the nucleus, and the remaining portion is 
 
THE LENS. 93 
 
 called the cortex. The nucleus of the lens is a hard- 
 ening or sclerosis which begins to form at the 
 center of the lens soon after birth, and gradually 
 increases until old age (about seventy years), 
 when the entire lens may be said to be sclerosed, or 
 hardened, or to become all nucleus. Sclerosis does 
 not mean a loss of transparency, though the lens 
 may become amber colored as age advances. It is 
 this gradual hardening of the lens from its center 
 to the periphery that causes in great part the loss 
 of accommodation which takes place from youth to 
 old age. The lens is made up of long six-sided 
 fibers which pass to and from the anterior and 
 posterior surface of the lens. These fibers are held 
 together by outward pressure and also by a cement 
 substance (liquor Morgagni). The anatomy of the 
 lens may be described as made up of three primary 
 sectors, giving it a Y-shape and these prongs of 
 the Y are still further branched, making the Y 
 something of a star figure, called the " lens star." 
 The lens is surrounded by its transparent capsule. 
 That portion of the capsule on the anterior surface 
 is called the anterior capsule, and that on the pos- 
 terior surface is called the posterior capsule. The 
 anterior capsule is thicker than the posterior and 
 has a layer of epithelial cells lining its inner sur- 
 face, and it is from these cells that the lens fibers 
 have their origin. The lens is without nerves or 
 vessels and is said to receive its nourishment by 
 osmosis. The lens ligament is a thin, fibrous mem- 
 
94 THE OPHTHALMOSCOPE. 
 
 brane, having its origin at the ciliary body and 
 many of its fibers may be traced to the ora ser- 
 rata. As these fibers pass from the ciliary processes 
 part of them adhere to the anterior capsule and part 
 to the posterior, and some few to the capsule at 
 the equator of the lens. The triangular space at 
 the equator of the lens formed between the an- 
 terior and posterior fibers of the ligament is called 
 the canal of Petit. The function of the lens is to 
 maintain the focus at the macula of rays of light 
 entering the eye from various distances at differ- 
 ent times. 
 
 The Vitreous (corpus vitreum, meaning a body 
 of glass) is a transparent, colorless substance of the 
 consistency in health of gelatinjelly, and fills the 
 large posterior or scleral chamber of the eye. It 
 lies in contact with the optic disc, the retina, ciliary 
 body and lens, the latter with its capsule resting 
 in a depression in the vitreous called the fossa patel- 
 laris. The vitreous is made up of round and 
 branched cells, and, like the lens, does not contain 
 blood vessels or nerves. It receives its nourishment 
 from the choroid, the ciliary body and vessels of 
 the retina. The vitreous is surrounded by a very 
 thin, transparent, structureless membrane called the 
 lrv_aloid. During intra-uterine life the vitreous is 
 perforated in its antero-posterior axis by the hy- 
 aloid artery and vein which pass from the disc to 
 the posterior surface of the lens. These vessels 
 normally become absorbed before birth, but in their 
 
OPTIC NERVE. 95 
 
 place there remains a canal known as a lymgh chan- 
 nel. Canal of Cloquet. Normally this cannot be 
 seen with the ophthalmoscope. 
 
 Optic Nerve. The nerve is covered in its course 
 from the optic foramen by a loose sheath ((jural 
 sheath) which is continuous with the dura mater. 
 This sheath, as already stated, is also continuous 
 with the sclerotic coat. Immediately surrounding 
 the nerve is the gial_5liajh, which is continuous 
 with the pia mater. This pial sheath sends pro- 
 longations in between the bundles of nerve fibers 
 and extends as far forward as the lamina cribrosa. 
 As the outer sheath covers the nerve loosely and 
 the pial sheath beneath adheres closely, there is 
 left an intervening space known as the intervaginal, 
 containing a portion of the arachnoid, and this 
 space is continuous posteriorly with the subarach- 
 noid within the cranium, but anteriorly at the 
 membrana cribrosa it is more or less of a cul-de- 
 sac. The arachnoid membrane contains many mi- 
 nute openings, and it is by means of these openings 
 that the spaces each side of the arachnoid are in 
 free communication one with the other. Each optic 
 nerve fiber (about 500,000 in all) has its own indi- 
 vidual sheath (white matter of Schwann) until it 
 comes to the membrana cribrosa (Ic, Fig. 61), and 
 here each fiber loses its covering and collectively 
 these fibers pass through the foramen sclera and 
 go to assist in the formation of the retinal fiber 
 layer. 
 
96 THE OPHTHALMOSCOPE. 
 
 Lamina Cribrosa (Ic, Fig. 61), meaning sieve- 
 like, is composed of fibers from the sclera and some 
 from the pial sheath. These fibers traverse the 
 foramen sclera and serve as a support to the intra- 
 ocular contents and also to the optic nerve fibers. 
 
 Blood Vessels. The posterior ciliary arteries 
 perforate the scleral coat around the entrance of 
 the optic nerve where it enters the sclera, arid these 
 vessels send off branches which anastomose and 
 form an arterial circle called the circle of Haller. 
 From this circle fine twigs pass between the trans- 
 parent nerve fibers which lie anterior to the mem- 
 brana cribrosa, and they in turn anastomose with 
 branches from the central vessels of the nerve. 
 From this description the reader will understand 
 and appreciate the circulation which takes place in 
 the nerve head and that the vascularity of the disc 
 is connected with the choroidal as well as with the 
 .retinal system of vessels. The central artery of 
 [the retina is a branch of the ophthalmic which comes 
 [from the internal carotid. The retinal vein empties 
 into the ophthalmic vein and thence into the cavern- 
 ous sinus. 
 
 Optic Disc. The optic nerve fibers having 
 dropped their sheaths before passing through the 
 membrana cribrosa must also pass through a round 
 opening in the choroid (foramen of the choroid) 
 before they can spread out to form the fiber layer 
 of the retina. The foramen choroid is a distinct 
 opening in the choroid and this opening usually 
 
OPTIC DISC. 97 
 
 surrounds these fibers quite closely, but there are 
 many exceptions to this statement, for the foramen 
 choroid may be quite large and not embrace the 
 fibers closely, or it may touch the fibers at one side 
 only. The nerve fibers in the foramen choroid are 
 quite closely bunched together, and therefore as 
 they begin to separate they must bend almost at 
 right angles over the edge of the choroid to pass 
 into the retina. This bunching of all the nerve 
 fibers just where they bend and begin to separate 
 must form a prominence or elevation, and hence 
 another name for the optic nerve head is papilla. 
 As the fibers of the nerve head are transparent in 
 health it is not an easy matter to demonstrate this 
 elevation with the ophthalmoscope, consequently 
 some authorities dispute the correctness of the word 
 papilla and state that the optic nerve head is not 
 elevated, but is on a level with the surrounding eye 
 ground. It is at the disc that the blood enters and 
 leaves the retina. The disc is slightly to the nasal 
 side of the posterior pole of the eye. 
 
 The Macula. To the temporal side of the pos- 
 terior pole of the eye is found an area of most 
 acute vision (macula lutea) and at its center is a 
 depression which is circular or crescent or oval in 
 shape. This point is known as the center of sight 
 or "yellow spot," or fovea centralis; it is about 
 one millimeter in diameter (Plate I.). 
 
 Circulation at Macula. The macula is the most 
 vascular part of the retina. This is demonstrated 
 
 10 
 
98 THE OPHTHALMOSCOPE. 
 
 by the microscope, but the fovea (center of the 
 macula) itself has no vessels^ .Plate I.). 
 
 While it has been stated that the retina extends 
 forward to the ora serrata, yet some portion of the 
 retina may be traced forward onto the ciliary proc- 
 esses and also onto the posterior surface of the iris. 
 The distance from the center of the disc of the em- 
 j metropic eye to the macula is 4 millimeters. The 
 thickest part of the retina is on the disc, 0.42 of a 
 millimeter; at the ora serrata it is 0.14 of a milli- 
 meter, and at the fovea o.i millimeter. The arteries 
 of the retina are branches of the central artery and 
 can be traced forward to the ora serrata, but they 
 are terminal vessels and do not anastomose. The 
 large vessels are in the nerve fiber layer beneath the 
 internal limiting membrane, therefore in that part 
 of the retina nearest the vitreous. The smaller ves- 
 sels of the retina extend as deep as the internal 
 granular layer. The fovea and external layers of 
 the retina are non-vascular and are nourished by 
 plasma from the chorio-capillaris. The circulation 
 of the retina is described in Chapter IV. The func- 
 tion of the retina is to convert the rays of light from 
 external objects into nervous stimuli. The macula 
 differs from the rest of the retina in that it is com- 
 posed entirely of cones closely packed together and 
 each cone is the terminal of a single nerve fiber, and 
 it is these cones in this area which have the most 
 acute vision, whereas in the periphery of the retina 
 the cones are not so numerous, the rods predomi- 
 
CONGENITAL ANOMALIES. 99 
 
 nating, and the retinal fibers have several terminals 
 instead of only one, as at the macula. 
 
 Congenital Anomalies. 
 
 To avoid errors in diagnosis the observer should 
 be prompt to recognize variations from the stan- 
 dard condition known as anomalies. 
 
 Cornea. Congenital anomalies of the cornea are 
 extremely rare, and are usually recognized as opaci- 
 ties. These may or may not be vascular. The 
 cornea of the young embryo is opaque and gradu- 
 ally becomes transparent toward the time of birth, 
 but if for any reason this process is interrupted the 
 infant may be born with an opacity of the cornea. 
 Or if an ulcer of the cornea took place during intra- 
 uterine life an opacity may be recognized soon after 
 birth. Dermoid tumors are occasionally seen and 
 are situated at the corneo-scleral margin. 
 
 Microphthalmos (small eye), or an undevel- 
 oped eye, is occasionally observed, and in this con- 
 dition the cornea is correspondingly small. 
 
 Sclerophthalmia is another rare congenital con- 
 dition in which the sclera encroaches on the cornea, 
 so that there is not the usual amount of clear cornea 
 observed. 
 
 Iris. As the color of the iris is so varied in dif- 
 ferent people and races the color itself cannot be 
 said to be anomalous, but when an iris is variously 
 colored it is spoken of as heterochromia iridis. Or 
 if an eye has a different colored iris from its fellow 
 
IOO THE OPHTHALMOSCOPE. 
 
 then the condition of the two eyes is spoken of as 
 heterophthalmos. Occasionally an iris has a few 
 or many pigment spots (black or brown) scattered 
 through it, and such an iris is spoken of as resem- 
 bling a leopard or tiger skin, called spotted or pie- 
 bald iris. Rarely one or both eyes may not have 
 an iris, and this is spoken of as irideremia or an- 
 iridia, and such an eye will naturally have defective 
 vision, and not unusually it is nystagmic. 
 
 Congenital Ectropion of the Uvea. This is a 
 rounded mass of the uveal layer projecting around 
 the pupillary edge of the iris onto the anterior por- 
 tion of the iris. 
 
 Rarely one or both eyes may have a cleft in the 
 iris, and this is called a coloboma (/coXd^w/xa, " mu- 
 tilation "). This usually appears in the lower por- 
 tion giving the pupil a shape not unlike a keyhole 
 in a door, and hence is sometimes called a " key- 
 hole " pupil. This being a congenital condition it 
 must be differentiated from a coloboma due to an 
 iridectomy, and this latter is usually made in the 
 upper portion of the iris (an inverted keyhole). 
 There is also an incomplete coloboma occasionally 
 seen not extending to the ciliary margin. Colo- 
 boma of the iris may occur in one or both eyes ; if 
 found in one eye it is usually the left. Coloboma of 
 the iris is occasionally associated with a similar con- 
 dition in the lens and choroid. 
 
 Pupil. Normally the pupil lies a trifle to the 
 nasal side of the center of the iris, and while this 
 
THE PUPIL. 
 
 101 
 
 is quite difficult to recognize, yet there is a con- 
 genital condition in which the pupil is markedly 
 displaced, and this condition is promptly detected. 
 This displacement may be in any portion of the 
 iris and is spoken of as corectopia or ectopia pu- 
 pillae. Corectopia may affect both irises symmetric- 
 ally, and it has been known as a family charac- 
 teristic. 
 
 Occasionally an iris is seen having more than one 
 pupil and this condition is called polycoria. The 
 
 FIG. 62. Varieties of Persistent Pupillary Membrane. (Wickerkie- 
 wicz. 1 ) 
 
 additional pupil may be situated very near the nor- 
 mal pupil. Another congenital condition sometimes 
 observed occupying the pupillary area is what is 
 
 1 Sojous Annual. 
 
102 
 
 THE OPHTHALMOSCOPE. 
 
 known as pupillary membrane (Fig. 62). This 
 may appear as a few dark threads or as a broken 
 mass of pigment with many shreds passing across 
 from the anterior capsule of the lens in the pupillary 
 area and attached to the small circle of the iris. 
 Capsule pupillary membrane is a portion of pupil- 
 lary membrane seen extending from the iris to the 
 anterior capsule of the lens and if not carefully in- 
 spected with a magnifying lens or loupe, could be 
 
 FIG. 63. Various forms of Opacity of the Lens. The upper row as 
 they appear by Oblique Illumination. The lower row as seen by Trans- 
 mitted Light (Direct Method). By oblique illumination the opacity is 
 seen in its true color. 
 
 i, Anterior polar cataract ; 2, posterior polar cataract ; 3, lamellar 
 cataract ; 4, early stage of senile cataract ; 5, senile cataract not quite 
 mature or ripe, for if the light is thrown on the eye from the right 
 side the iris casts a shadow in the lens ; 6, subluxation of the lens. 
 (Jennings.) 
 
 mistaken for a posterior synechia. Pupillary mem- 
 brane is the remnant of the vascular membrane 
 which encircles the lens in intra-uterine life and fails 
 to become absorbed before or shortly after birth. 
 
CATARACT. . 103 
 
 Cysts and naevi of the iris have been noted as con- 
 genital anomalies. 
 
 Lens. Rarely an eye may be born without a 
 lens (congenital aphakia). Congenital anomalies 
 of the lens are usually in the form of cataract as 
 follows : 
 
 Anterior Polar Cataract (No. I, Fig. 63). At 
 the anterior pole of the lens is seen a small white 
 spot the size of a pin point or a pin head ; it usually 
 involves the capsule and in many instances is pyra- 
 midal in shape and is sometimes called pyramidal 
 cataract. This variety of cataract is a congenital 
 condition and may be caused by a perforation of 
 the cornea in intra-uterine life or early infancy, 
 and may be associated with inter-pupillary mem- 
 brane. If carefully looked for, the corneal opacity 
 may usually be found. 
 
 Posterior Polar Cataract (No. 2, Fig. 63). 
 This variety of opacity, as its name implies, is in 
 the posterior portion of the lens, and if anything, a 
 trifle to the nasal side of the pole. It is somewhat 
 star-shaped and has been called " stellar cataract." 
 Just as interpupillary membrane showing on the 
 anterior capsule is the result of unabsorbed blood 
 vessels, so posterior polar cataract is said to be 
 caused by a portion of an unabsorbed vessel wall 
 at this point. 
 
 Lamellar, or Zonular, Cataract (No. 3, Fig. 
 63). As its name implies, this is a variety of cat- 
 aract characterized by a layer or zone of the lens 
 
IO4 THE OPHTHALMOSCOPE. 
 
 being opaque and the remaining portion clear; in 
 other words, the nucleus may be clear and also the 
 cortex, but the intermediate portion is opaque; 
 hence this particular variety is also correctly called 
 perinuclear cataract. There are many departures 
 from this condition. This variety of cataract is 
 usually a condition at birth. 
 
 Congenital dislocation of the lens (No. 6, Fig. 
 63). This is usually a partial dislocation and 
 therefore not complete. Some portion of the lens 
 usually occupies a part of the pupillary area. This 
 condition is spoken of as ectopia lentis. The lens 
 is usually dislocated upward and this is usually a 
 condition of both eyes. Coloboma of the lens is not 
 common, but does occur and is frequently present 
 with coloboma of iris and choroid. Double colo- 
 boma of the lens has been reported. Carefully ex- 
 amined it appears to be a slight notch in the edge of 
 the lower portion of the lens, and sometimes as 
 much as one-quarter of its substance. 
 
 Lenticonus. This rare anomaly is a conic con- 
 dition of the lens at the center of its anterior or 
 posterior surface, usually the latter. With the 
 retinoscope (plane mirror) or the concave mirror 
 of the ophthalmoscope, or by oblique light, this 
 cone may be seen, as it resembles a drop of oil at 
 the point mentioned. 
 
 Choroid. The principal congenital anomaly of 
 the choroid is that of coloboma (coloboma cho- 
 roidese), which usually includes a corresponding 
 
CHOROID. 105 
 
 section of the retina, and it is not unusual to have 
 the coloboma of the iris also present. Coloboma of 
 choroid is an arrest of development in the eye in 
 intra-uterine life before the choroidal fissure has 
 become closed. This condition is recognized just as 
 hare-lip and cleft palate are recognized, as congeni- 
 tal anomalies, and occasionally as an hereditary con- 
 dition. Coloboma of the choroid is of course seen 
 with the ophthalmoscope and is recognized by its 
 triangular shape, apex toward or embracing the 
 nerve head and the base of the triangle at the ciliary 
 processes. The white sclera shows brilliantly 
 where the choroid and retina are absent and a few 
 ciliary vessels are seen in the area of the coloboma 
 and scattered pigment about the sharp cut edges of 
 the coloboma. If the coloboma of the choroid exists 
 alone the presence of the retina is recognized as a 
 thin gauzy veil covering the cleft as also the retinal 
 vessels passing over it. Coloboma of the choroid 
 is not always complete, and is not always triangular 
 in shape. It may be round or oval and may include 
 the nerve head, or it may occupy the macula, and is 
 then called a macular coloboma. The coloboma 
 including the disc appears as a cleft or depression 
 and is usually in the lower portion, or the entire 
 nerve head may appear abnormally large. The 
 field of vision is cut off, corresponding to the colo- 
 boma (Chapter VI.). 
 
 Persistent Hyaloid Artery. In embryonic life 
 the central artery of the retina sends a branch for- 
 
106 THE OPHTHALMOSCOPE. 
 
 ward through the central portion of the vitreous, 
 Canal of Cloquet, to the posterior surface of the 
 lens, and here it branches and covers the lens on 
 its posterior as well as its anterior surface like a 
 net, called vascular membrane. Usually all these 
 vessels are absorbed before the birth of the infant, 
 but if the main branch from the disc to the lens, 
 or only a portion of it, is absorbed, then the re- 
 maining portion is seen with the ophthalmoscope 
 and it usually appears as a dark gray colored 
 thread or band attached to the disc and stretching 
 out into the vitreous and moving with the rotation 
 of the eyeball. There are many variations from 
 this usual one here described (see pupillary mem- 
 brane, Fig. 62). 
 
 Albinism ( Albinismus) , Albino. This is a 
 congenital absence of pigment in the choroid and 
 iris. True albinism is not often seen, and most 
 cases that are spoken of as albinism have some 
 slight pigmentation in the iris or iris and choroid. 
 The pupil appears pinkish in color, as does also the 
 iris and the eye ground. The choroidal circula- 
 tion is conspicuous with the ophthalmoscope. The 
 eyes have very poor vision, glasses are always 
 necessary, and usually for some form of myopia. 
 Nystagmus is generally quite conspicuous and the 
 patient is usually a blonde. 
 
 Opaque Nerve Fibers. Medullary sheaths. 
 The fibers of the nerve usually drop their outer or 
 medullary sheaths (white matter of Schwann) at 
 
OPAQUE NERVE FIBERS. 
 
 the lamina cribrosa. Occasionally in one eye, rarely 
 in both eyes, some of these sheaths are reinstated 
 just as the fibers emerge from the disc and are car- 
 ried into the surrounding retina, sometimes and 
 usually for a short distance only, but in rare in- 
 stances for a considerable distance. These opaque 
 fibers, a congenital condition, are usually seen at 
 the upper edge of the disc (Plate IX.), or at the 
 lower edge, or at both the upper and lower edges. 
 They are seldom seen at the inner or nasal side, 
 and some authorities state that they are never seen 
 at the temporal side. In appearance these medul- 
 lary fibers are glistening white, sometimes bluish 
 white in color and have feathered or striated edges. 
 The retinal vessels may be hidden in these fibers 
 and reappear beyond and also on the disc. The be- 
 ginner should not mistake these fibers for the snow 
 bank of Bright's disease (Plate IV.). These med- 
 ullary fibers may be quite extensive, or few in 
 number. As they never appear at the macula, cen- 
 tral vision is unimpaired by them, though the nor- 
 mal blind spot may be enlarged by their presence. 
 Connective Tissue. This is occasionally seen to 
 obscure the disc in part or it may obscure a vessel 
 or part of a vessel on the disc. This tissue resem- 
 bles cotton or wool, it is never very extensive, it 
 is usually congenital, and, like medullary sheaths, 
 does no harm in the healthy eye. It might act in- 
 juriously if papillitis should development in such 
 an eye. 
 
CHAPTER IV. 
 
 THE NORMAL EYE GROUND. 
 
 As it is necessary for the beginner in ophthal- 
 moscopy to get a clear understanding and picture 
 of the interior of a healthy or standard eye 1 before 
 studying the pathologic or sick eye, it is the pur- 
 pose of the writer to describe this condition mi- 
 nutely and carefully, so that after this has once 
 been mastered, the student will be in a position to 
 appreciate any change or changes or departures 
 from the standard condition. 
 
 The Normal Eye Ground. The inner surface 
 of the posterior two-thirds of the eye is commonly 
 spoken of as the " fundus," from the Latin mean- 
 ing " bottom," but the term " eye ground " is ap- 
 plied to the entire inner surface of the eye extend- 
 ing well forward to the ciliary processes. The 
 objective points in the eye ground will be described 
 individually and with the idea of systematizing the 
 study. 
 
 Color of the Eye Ground. Primarily this is 
 due to the red reflex from the choroidal coat, which 
 by virtue of its extensive blood supply and pig- 
 
 " Five-sixths of the art of ophthalmoscopy are contained in a 
 knowledge of the normal eye, the rest is a series of representations 
 which can be read almost at sight." Edward G. Loring, 1886. 
 
 108 
 
COLOR OF EYE GROUND. 109 
 
 mentation enters more extensively into the pro- 
 duction of the color of the eye ground, the reflex 
 and the ophthalmoscopic picture than any other 
 structure. But there is nothing uniform about 
 the " reflex," or color, of the interior of the eye, 
 in fact it has already been stated that the color of 
 the " reflex " is controlled by the clearness or trans- 
 parency of the media, by the refractive condition, 
 the amount of pigment in the tissues, and by the 
 size of the pupil. The eye of the albino would 
 give a pink glow to the eye ground, whereas the 
 mulatto or dark-haired individual would very likely 
 have a very dark-colored fundus. The eye ground 
 is not colored uniformly throughout, and many 
 eye grounds appear much lighter in color as the 
 periphery is approached; this is due to an unequal 
 distribution of pigment. Speaking generally, the 
 color effect of the eye ground is spoken of as 
 " orange red " in most eyes, and this seems a fair 
 description, but this color effect may be altered or 
 appear to change in intensity by the character or 
 kind of light reflected into the eye. The indirect 
 method gives a much darker red effect than the 
 direct method. With these statements about the 
 color of the eye ground, it is the sincere hope of the 
 writer that the student who looks into a healthy 
 eye for the first time, will not feel disappointed be- 
 cause he does not obtain the same color effect that 
 has been impressed upon his mind or brain by 
 studying a certain colored picture in an atlas. 
 
I IO 
 
 THE OPHTHALMOSCOPE. 
 
 Colored pictures of the fundus are good in their 
 way as far as the execution of the drawing is con- 
 cerned, and sometimes true as regards the color, 
 
 FIG. 64. HEAD OF THE OPTIC NERVE. 
 
 A, Ophthalmoscopic view : Somewhat to the inner side of the center 
 of the papilla the central artery rises from below, and to the temporal 
 side of it rises the central vein. To the temporal side of the latter 
 lies the small physiologic excavation with the gray stippling of the 
 lamina cribrosa. The papilla is encircled by the light scleral ring (be- 
 tween c and d), and the dark choroidal ring at d. B, Longitudinal sec- 
 tion through the head of the optic nerve: Magnified 14 X i. The trunk 
 of the nerve up to the lamina cribrosa has a dark color because it con- 
 sists of medullated nerve-fibers, n, which have been stained black by 
 Weigert's method. The clear interspaces, se, separating them, corre- 
 spond to the septa composed of connective tissue. The nerve-trunk is 
 enveloped by the sheath of pia mater, p, the arachnoid sheath, ar, and 
 the sheath of dura mater, du. There is a free interspace remaining 
 between the sheaths, consisting of the subdural space, sd, and the sub- 
 arachnoid space, sa. Both spaces have a blind ending in the sclera at e. 
 The sheath of dura mater passes into the external layers, .sa, of the 
 sclera, the sheath of pia mater into the internal layers, si, which latter 
 extend as the lamina cribrosa transversely across the course of the optic 
 
THE OPTIC NERVE. I I I 
 
 but when the color effect is carefully studied it 
 will soon become apparent that many such pic- 
 tures are very erroneous and grossly misleading. 
 It goes without saying that faulty impressions 
 gained from a poorly colored picture, will give a 
 healthy fundus the appearance of being hopelessly 
 pathologic by comparison. No illustration, how- 
 ever exact it may be, can ever compete with the 
 actual picture as viewed with the ophthalmoscope. 
 The Optic Nerve. Also called the disc (some- 
 times " disk "), or nerve head, or papilla, or intra- 
 ocular end of the optic nerve (Fig. 64 and Plate 
 I.). The normal and real size of the disc macro- 
 scopically is 1.5 millimeters, and its position in the 
 fundus is about icf_or_i2 to the inner side of the 
 posterior pole of the eye. It corresponds to what 
 is known as the normal blind spot in the field of 
 vision. As the retina has been described as the 
 optic nerve unfolded, the optic disc may then be 
 
 nerve. The nerve is represented in front of the lamina as of light 
 color, because here it consists of non-medullated and hence transparent 
 nerve-fibers. The optic nerve spreads out upon the retina, r, in such a 
 way that in its center there is produced a funnel-shaped depression, the 
 vascular funnel, b, on whose inner wall the central artery, a, and the 
 central vein, v, ascend. The choroid, ch, shows a transverse section of 
 its numerous blood-vessels, and toward the retina a dark line, the pig- 
 ment epithelium ; next the margin of the foramen for the optic nerve, 
 and corresponding to the situation of the choroidal ring, the choroid 
 is more darkly pigmented. ci is a posterior short ciliary artery which 
 reaches the choroid through the sclera. Between the edge of the chor- 
 oid, d, and the margin of the head of the optic nerve, c. there is a nar- 
 row interspace in which the sclera lies exposed, and which corresponds 
 to the scleral ring visible by the ophthalmoscope. (Description and 
 figure from Fucks.) 
 
112 THE OPHTHALMOSCOPE. 
 
 described as the part of the nerve where the un- 
 folding begins to take place. The disc is the first 
 and chief landmark in the study of the eye ground, 
 and most descriptions and examinations of the 
 eye ground have the disc as the central point of 
 departure. 
 
 For purposes of study, the disc (see Plate I.) in 
 most eyes may be conveniently divided into three 
 parts : 
 
 1. The central portion, which is usually quite 
 light in color, contains the central vessels with 
 the porus opticus (if present), the physiologic cup 
 (if present), and a part of the membrana cribrosa 
 (if present). Any one, or any two, or all three of 
 these conditions may be seen in a single disc, or 
 they may all be absent. 
 
 2. The margin, one or two millimeters in width, 
 represents the demarkation from the surrounding 
 fundus. This margin is whitish or of a pale yellow 
 color. 
 
 3. The space between the margin and the center 
 is the intermediate zone, and it is this zone that 
 gives the disc its true color and should have careful 
 and minute consideration at all times as bearing 
 upon an intimate knowledge of the normal and the 
 pathologic, i. e,, atrophy and hyperemia, etc. In 
 health this intermediate zone is considered to be 
 pink or yellowish red in color. 
 
 Shape of the Disc. This varies; it may be 
 round, oval or irregular in outline. Usually it 
 
PHYSIOLOGIC CUP. 113 
 
 appears vertically oval. The oval shape is usually 
 explained by a refractive error, astigmatism. The 
 irregular shape may be explained by some irregu- 
 larity in the refractive media, or it may be a con- 
 genital condition. The disc margin in health is 
 usually quite distinct and easily recognized. 
 
 Porus Opticus. The retinal artery and vein as 
 they pass through the axis of the optic nerve are 
 covered by a layer of connective tissue called a 
 canal, and at the disc this canal is occasionally 
 expanded so that the observer can see down into 
 it; this is called the porus opticus. If this canal 
 is not expanded and the vessels bend sharply as 
 they enter the retina, then there is no porus opti- 
 cus present. 
 
 Physiologic Cup. At or near the center of the 
 disc (never occupying the entire disc) is often seen 
 in health a depression or pit; this is called a cup, 
 and being normal is called physiologic, in other 
 words the " physiologic cup." It is made by the 
 separation of the nerve fibers after passing 
 through the lamina cribrosa. This is in contra- 
 distinction to another depression to be described 
 later, and known as the glaucoma cup, which oc- 
 cupies the entire disc (Plate XII.), and this again 
 L distinguished from another very shallow de- 
 pression called a saucer depression, not a cup- 
 ping. This is seen in optic atrophy, also to be 
 differentiated elsewhere (Plate X.). This physi- 
 ologic cupping may be shallow (Plate I.) or quite 
 ii 
 
114 THE OPHTHALMOSCOPE. 
 
 deep; it may have shelving or abrupt edges, or it 
 may be funnel-shaped or conical, or the nasal side 
 may be abrupt or steep and the temporal side shelv- 
 ing gradually toward the edge of the disc; this 
 latter is quite a common variety. The diameter 
 of the physiologic cup varies in different eyes; it 
 may be one-fourth or one-third or half the size of 
 the disc. Therefore, it may be said that the physi- 
 ologic cup is not uniform in all eyes or in the same 
 pair of eyes, and in fact it may not be present at 
 all, or it may be seen in one eye and not in the other 
 eye of the same patient. The vessels on the disc 
 naturally keep close to the disc and therefore fol- 
 low its surface, and if cupping is present the ves- 
 sels naturally curve over its edges and are seen at 
 the bottom of the cup. The color of the cup is 
 usually white, and at times, by a certain reflection 
 of the light, may appear glistening, and it is cer- 
 tainly much lighter in color than the remaining 
 portion of the nerve. The depth of the cup may be 
 estimated by the difference in the strength of the 
 lens used in the ophthalmoscope to see the edge of 
 the cup, and the other lens required to see the bot- 
 tom of the cup, or the difference in the strength of 
 the lens used to focus a vessel at the edge of the 
 cup, and the strength of the other lens required to 
 focus the same vessel at the bottom of the cup. The 
 difference in level between the bottom of the cup 
 and the prevailing eye ground can be easily demon- 
 strated by what is called the garallax. To do this 
 
MEMBRANA CRIBROSA. 115 
 
 with the direct method, the observer watching the 
 bottom of the cup and then moving his head per- 
 pendicular to the line of sight, the edge of the cup- 
 ping with the surrounding eye ground will appear 
 to move in the opposite direction. The bottom of 
 the cup will appear to move with the movement 
 of his head. Remembering that every three diop- \ 
 ters represent about one millimeter in depth, then i 
 if the edge of the cup is seen without any lens and 
 the bottom of the cup is seen with minus three, the 
 depth of that cup is about one millimeter ; or if the 
 edge of the cup is seen with a plus six and the 
 bottom of the cup is seen without any lens at the 
 sight-hole of the ophthalmoscope, this would make 
 a difference of six diopters, and the depth of the 
 cup would therefore be approximately two milli- 
 meters. 
 
 The Membrana Cribrosa (Plates VI. and X.). 
 At the bottom of the cupping or at a corresponding 
 point on the disc, if there should not happen to be 
 any cupping present, there is frequently seen a 
 gray stippling, or an area composed of little gray 
 spots with white interspaces; these spots represent 
 openings in the sclerotic coat for the passage of 
 the transparent optic nerve fibers. The gray spots 
 represent the nerve fibers and the white network is 
 the lamina cribrosa or scleral tissue extending 
 across the space through which the nerve fibers 
 enter. 
 
 The Scleral Ring (Fig. 64). As the transpa- 
 
Il6 THE OPHTHALMOSCOPE. 
 
 rent nerve fibers pass from the disc into the retina 
 they pass over or through the foramen choroid 
 and if this opening is large and its edges equi- 
 distant from the entering fibers, naturally the 
 white sclera will appear through the transparent 
 fibers, giving the disc the appearance of being sur- 
 rounded by a light-colored ring. This according 
 to Fuchs and others is known as the scleral ring. 
 Occasionally the foramen choroid approximates 
 the nerve fibers on one side and this leaves the 
 sclera exposed through the nerve fibers on the 
 opposite edge, giving the sclera the appearance of 
 a crescent (Plate XL). This crescent is usually 
 at the temporal side. If the choroidal foramen is 
 small and approximates the nerve fibers on all 
 sides, then the scleral ring or crescent will be 
 absent. In myopic eyes and eyes with glaucoma 
 there is frequently seen at the temporal edge of 
 the disc a white crescent or this crescent may con- 
 tinue completely around, forming a ring; this is 
 due to the absorption of pigment and the scleral 
 tissue appears through the transparent retina. Ac- 
 cording to Jaeger this is not a scleral ring, but con- 
 nective tissue. 
 
 The Choroidal Ring. This may or may not be 
 present (Plate I.), or may appear as a crescent; 
 choroidal crescent. It usually contains in its com- 
 position a great deal of pigment and this pigment 
 may be very irregular or possibly there may 
 be just one large mass of pigment on one side of 
 
PLATE I. 
 NORMAL FUNDUS OF LEFT EYE OF A HEALTHY LAD. 
 
 J. M. T. Aged 10 years. 
 
 History. A blonde with light hair and pink complexion. Blue 
 irises. Direct method. Refraction almost emmetropic (+0.50 D.). 
 Disc is round, having light-colored center, distinct margins and 
 yellowish-red intermediate zone. Choroidal ring almost complete 
 and slightly more pigmented to the temporal side. Two cilio-retinal 
 vessels on the lower outer edge of disc passing toward the macula. 
 The crescentic fovea centralis, with surrounding blood-red area, is 
 unusually well shown and most typical at this young age. Veins 
 and arteries are slightly to the nasal side of the disc. The arteries 
 cross the veins on the disc, but in the periphery the veins cross the 
 arteries. 
 
 118 
 
PLATE I 
 
 Normal Fundus 
 
COLOR OF OPTIC DISC. 121 
 
 the disc; usually this is not pathologic. The cho- 
 roidal ring or crescent may be present with a 
 scleral ring or crescent, or it may be absent in one 
 or both eyes. 
 
 Color of the Optic Disc. This has been de- 
 scribed as resembling in color the marrow of a 
 healthy bone, or the " pink " of a sea shell, etc., but 
 this is not by any means a description that will 
 answer in every case, as the apparent color of the 
 disc is controlled in great part in health by the 
 surrounding eye ground, whether this is heavily 
 pigmented, as in the mulatto, or but slightly so, as 
 in the blonde, or whether there is an absence of pig- 
 ment, as in the albino, or whether there is a physi- 
 ologic cupping. The student should be ready to 
 make allowances for these contrasts. In health it 
 is the minute capillaries in the intermediate zone 
 together with connective tissue and nerve fibers 
 which give the disc its " pink " color or " orange 
 red " or yellowish cast. These minute capillaries 
 cannot be seen with the ophthalmoscope. Gener- 
 ally speaking, the disc is pale toward the temporal 
 side and at the center, while the nasal side is darker. 
 Plate I. furnishes a good illustration of a normal 
 disc in its coloring and shape, etc. The reader 
 should observe this and the other colored plates by 
 artificial light and not by day light, otherwise he 
 will be liable to get a faulty color impression. 
 
 The vessels seen on the disc (called central ves- 
 sels) soon branch and rebranch in the nerve fiber 
 
122 THE OPHTHALMOSCOPE. 
 
 layers, carrying the blood to and from the retina, 
 but they are not all of the same calibre nor do they 
 have the same curves or branches or twinings in 
 all eyes, or in the same pair of eyes. The central 
 retinal artery, a branch of the ophthalmic, enters 
 the optic nerve 10 or 20 millimeters back of the 
 eyeball and passes forward in the axis of the nerve 
 and may appear upon the disc as a single vessel, 
 or if it has branched in the nerve it will then ap- 
 pear as two vessels, and usually at the nasal side of 
 the center of the disc. Approximating the central 
 artery on its temporal side is the retinal vein which 
 may also be double; it accompanies the retinal 
 artery in the axis of the optic nerve and empties 
 into the superior ophthalmic vein or directly into 
 the cavernous sinus. 
 
 Size of the Vessels. The relative normal pro- 
 portion in size between arteries and veins is gen- 
 erally recognized as about two to three. The veins 
 are usually recognized by their larger size and 
 darker color. The arteries are lighter in color and 
 like the veins on and near the disc have a light 
 streak along their centers ; this is due to the reflec- 
 tion from the coat of the vessel. (Some authori- 
 ties state that this light streak is due to reflection 
 from the blood stream for the reason that if the 
 blood stream is cut off the vessel wall cannot be 
 seen.) This light streak (reflex streak) has the 
 effect or appearance of dividing the vessel into two 
 red lines. The veins being larger than the arteries 
 
SUMMARIZED DIFFERENCE. 123 
 
 and their walls not being so tense do not always 
 have the light streak so conspicuous. The small 
 arteries and veins do not have the light streak, and 
 therefore when looking at a small vessel in the 
 periphery of the eye ground the observer cannot 
 tell positively whether it is a vein or an artery un- 
 til he traces it toward the disc. The retinal vessels 
 do not anastomose. 
 
 Summarized Difference between Arteries and 
 Veins, i. e., 
 
 Arteries. Veins. 
 
 Bright red. Dull red. 
 
 Smaller. Larger. 
 
 Light streak well marked, and Light streak not always so 
 
 continues some distance along marked, except on and close to 
 
 the vessel. the disc. 
 
 Course is usually straight. Course is sinuous and may be 
 
 tortuous. 
 
 Pulsation seldom seen, except in Pulsation not unusual on disc. 
 
 disease. 
 
 Usually cross over veins. Usually cross under arteries. 
 
 It is interesting to note that in health the arteries 
 cannot be seen to pulsate, but that in some eyes, 
 venous pulsation (physiologic) may be seen to 
 take place in one or more of the large veins on or 
 near the disc. The explanation of the venous pul- 
 sation is by the systole of the heart filling the 
 arteries and making pressure on the vitreous, and 
 it is this interrupted pressure upon the vitreous that 
 momentarily compresses the vein on the disc; in 
 other words, the venous blood has apparently been 
 forced out of the vein until after the systole of the 
 heart when it refills, and this gives it the apparent 
 
 12 
 
124 THE OPHTHALMOSCOPE. 
 
 pulsation. This condition is not present in all eyes, 
 and when seen does not necessarily mean disease. 
 This pulsation can be produced and observed by 
 making considerable pressure with the finger on the 
 globe of the eye that is being examined. An 
 anomalous artery of medium size is occasionally 
 seen to curve over from the temporal edge of the 
 disc and to pass toward the macula (Plate I.) ; oc- 
 casionally more than one vessel is seen. This ves- 
 sel has no connection with the blood supply above 
 described, but is one of the ciliary vessels, and since 
 it has appeared in the retina is called a cilio-retinal 
 vessel. In embolism, etc., this vessel may occa- 
 sionally be of great value to a patient in preserving 
 some useful vision. The retinal arteries and veins 
 while possessing many anomalies, and occasionally 
 a retinal artery and vein may be seen to twine 
 around each other, yet they pursue a sufficiently 
 regular course up and down from the disc to be 
 named accordingly, i. e., upper nasal artery and 
 vein, upper temporal artery and vein, lower nasal 
 artery and vein, lower temporal artery and vein. 
 Arteries are seen to cross veins, and veins to cross 
 arteries, but veins are seldom seen to cross veins, 
 and it is denied that arteries ever cross arteries. 
 
 The Retina. As the fibers in the optic nerve, 
 together with the connective tissue which make up 
 the major portion of the retina, are transparent, 
 the retina (anterior to its epithelial layer) is in 
 health said to be invisible, but this is not altogether 
 
THE RETINA. 125 
 
 true, for under certain conditions of light and po- 
 sition of the fundus at an angle, the retina may be 
 recognized as a thin gauze or veil, and at times in 
 young subjects (not in the aged) during the act of 
 accommodation light streaks resembling the waves 
 or sheen of a piece of silk may be seen to pass over 
 the retina, called shot silk retina. The retinal 
 vessels occupying the nerve fiber layers mark the 
 location of the retina. These vessels, especially on 
 and about the disc, appear to be slightly elevated, 
 and in the general eye ground appear to be lying 
 well in front of the choroid and not directly upon 
 it. In young subjects the observer will at times see 
 a circle about the macula; this indicates accommo- 
 dative effort and is not a sign of disease. In some 
 eyes (usually myopic) the observer may occasion- 
 ally recognize a crescent-shaped reflex at the nasal 
 side of the disc; this is called the "Weiss reflex," 
 and some authorities claim that it is indicative of 
 progressing myopia. 
 
 Macula Lutea. The position of the macula lutea 
 in the fundus is about two discs in diameter to the 
 temporal side of the disc and slightly below the 
 horizontal meridian, it is slightly larger than the 
 disc. The macula is recognized as being oval in 
 shape with its long diameter horizontally, it is 
 darker in color than the rest of the fundus and its 
 edges gradually shade into the color of the eye 
 ground. At the center of the macula lutea is the 
 fovea centralis (center of sight, "fundus f ovea " 
 
126 THE OPHTHALMOSCOPE. 
 
 or fovea) ; this is a depression, and its edges give 
 a reflex. It is very small and appears as a bright 
 spot one or two millimeters in diameter. In many 
 eyes it appears as a tiny crescent (Plate I.). It is 
 rather lighter in color than the surrounding eye 
 ground. The macular region is that portion of the 
 eye ground immediately surrounding the fovea cen- 
 tralis. The macular region contains minute capil- 
 laries, but it is impossible in healthy eyes to recog- 
 nize them with the ophthalmoscope. The beginner 
 with the ophthalmoscope always has difficulty 
 in seeing and studying the macula unless a mydri- 
 atic has been instilled, for immediately that the 
 bright light falls on this extremely sensitive por- 
 tion of the fundus the iris contracts and the pupil 
 gets so small that it is almost impossible to see 
 into the eye, and with this small pupil comes the 
 corneal reflex, which adds to the difficulty of seeing 
 the fundus. The macula can best be studied in 
 subjects less than twenty years of age. In old 
 people the macula is not so conspicuous. For the 
 observer to study the macula, the pupil should be 
 dilated and the patient told to look into the mirror. 
 The Choroid. This structure is distinguished 
 principally by the character of its circulation; the 
 vessels (veins and arteries) all appear alike, they 
 are large, numerous and flattened, and each variety 
 anastomoses freely, and they are without the light 
 streak. Pigment areas between the vessels are also 
 distinctive of this tunic (albinos excepted). The 
 
THE CHOROID. 127 
 
 retinal vessels always appear in front of the cho- 
 roidal vessels. The choroidal circulation is best 
 studied in the blonde or albino, and especially in 
 the latter where the normal pigment between the 
 choroid and retina is absent, and the vessels appear 
 red on a white background. In some instances, 
 however, the choroidal circulation becomes so con- 
 spicuous that at times it is difficult to study the 
 retinal circulation (Plate VII.). In other in- 
 stances the dark pigmentation of the choroid is 
 quite conspicuous, with the characteristic choroidal 
 vessels giving it a striped or tesselated appearance, 
 called " choroide tigree." The choroidal circula- 
 tion may be seen in many eyes toward the periphery 
 of the eye ground. In many healthy eyes the cho- 
 roidal circulation cannot be seen, except a small 
 portion well forward toward the ora serrata. 
 
 Differential Diagnosis between Retinal and 
 Choroidal Vessels. 
 
 Choroidal Vessels. Retinal Vessels. 
 
 More numerous. Not so numerous. 
 
 Larger size. Smaller size. 
 
 Close together. Separated. 
 
 Nearly parallel. Divergent as they go toward the 
 
 periphery. 
 
 Frequently anastomose. Do not anastomose. 
 
 Do not diminish in size at Diminish in size at periphery. 
 
 periphery. 
 
 Veins and arteries not distin- Veins and arteries distinguish- 
 
 guishable. able. 
 
 Central light streak absent. Central light streak present. 
 
 Flat or riband-like appearance. Cylindrical form. 
 
CHAPTER V. 
 
 STRUCTURAL ALTERATIONS OR CHANGES IN THE CORNEA, 
 AQUEOUS HUMOR, IRIS, LENS AND VITREOUS HUMOR 
 WHICH ARE INDICATIVE OF DISEASE OR INJURY. 
 
 The Cornea. Examining the cornea by the 
 oblique illumination it will always, even in health, 
 have more or less of a faint smoky appearance, 
 whereas by ordinary daylight it appears as highly 
 polished and perfectly transparent. This smoky 
 appearance does not mean a want of transparency 
 but* is due to its anatomic construction of lamellae, 
 etc., see description, Chapter III. This haze, or 
 smoky appearance, varies with age, is less conspic- 
 uous in infancy and becomes more conspicuous in 
 the aged. At any age it may be made conspicuous 
 by having the light strike the cornea very obliquely. 
 By means of the oblique illumination one may de- 
 tect foreign substances which have lodged in or 
 upon the cornea, such as particles of dust, ashes, 
 cinders, wood, glass, iron and steel filings, emery, 
 powder grains, etc. Opacities on the under sur- 
 face of the cornea, in the disease known as " Des- 
 cemetitis " (" aquo-capsulitis " or " serous iritis ") 
 may also be recognized, and ulcers, wounds, phlyc- 
 tenules, blood vessels, as in pannus, and vascular 
 keratitis, opaque spots (opacities) in the .cornea 
 proper, arcus senilis, general loss of transparency 
 
 128 
 
THE CORNEA. I 29 
 
 in various forms of keratitis, especially the spe- 
 cific varieties, and also the haziness accompanying 
 glaucoma, may also be recognized if present. 
 
 Corneal scars, or opacities, are described accord- 
 ing to their size and density. A very faint haziness 
 of the corneal surface, affecting a part or the en- 
 tire cornea, is spoken of as a nubecula, meaning 
 " a mist," and may be compared to the appearance 
 of a clear glass just faintly breathed upon, or to 
 an atmosphere faintly foggy. A nebula is a cloud, 
 and therefore, represents a somewhat greater 
 density than a nubecula. A nebula may also affect 
 any part or the entire cornea. A macula is a spot 
 usually quite white in color but small in size, the 
 size of a pin head, for instance. Leucoma means a 
 milk white area, and is usually quite large and may 
 be spoken of as a large macula; such an opacity 
 can be seen at quite a distance from the eye and 
 without the necessity of employing oblique light 
 and condensing lens to see it. By the laity this 
 form of corneal opacity is often erroneously called 
 a cataract. An adherent leucoma is a leucoma hav- 
 ing some iris tissue bound to it, the result usually of 
 a perforating wound of the cornea (an ulcer) or an 
 injury whereby the iris has become entangled in 
 the wound. Corneal opacities may frequently be 
 seen with a dimly reflected light, and this is ob- 
 tained by having the gas flame further removed 
 from the mirror of the ophthalmoscope than for 
 the regular distance when examining the interior 
 
I3O THE OPHTHALMOSCOPE. 
 
 of the eye. If a foreign substance on, or an opacity 
 in, the cornea is recognized, its size, shape and loca- 
 tion should be carefully noted, and for this pur- 
 pose the cornea is divided into quadrants by 
 imaginary lines, so that an opacity or foreign sub- 
 stance may occupy the upper inner, upper outer, 
 lower inner, or lower outer, quadrant. The opac- 
 ity or foreign substance may be said to be at the 
 pole of the cornea, or just above or below or to the 
 nasal or temporal side of the pole of the cornea, as 
 the case may be. It may be described as being in, 
 or on, the cornea in the center of the pupillary area 
 or in the upper, or lower, or inner, or outer, portion 
 of the pupillary area. These minute descriptions 
 are of great importance to the careful ophthalmol- 
 ogist, as bearing upon a correct diagnosis and prog- 
 nosis as regards vision in many injuries and dis- 
 eases. The nearer the disease or injury is to the 
 pole of the cornea, the more unfavorable the prog- 
 nosis for good vision. Opacities or foreign bodies 
 of the cornea may be mistaken for opacities in a 
 deeper structure, and it is the duty of the observer 
 therefore to carefully study their location. Any 
 want of transparency in any portion of the cornea 
 that occupies the pupillary area (that portion of the 
 cornea corresponding to the underlying pupil), may 
 be diagnosed as in the cornea by having the pa- 
 tient turn the eye slowly in any given direction, 
 as the observer keeps the light reflected from the 
 mirror into the pupil and the opacity or foreign 
 
AQUEOUS HUMOR. 131 
 
 | 
 
 substance will move in the same direction in which 
 the patient turns the eye. An opacity in the pupil 
 itself, that is, one occupying the plane of the iris, 
 appears to maintain its relative position no matter 
 in which direction the patient turns the eye. 
 
 Aqueous Humor. This may be turbid or 
 muddy, the result of inflammatory products thrown 
 off by an inflammation of the iris or ciliary body, 
 or both. Blood in the anterior chamber (called 
 hyphema) or pus or leucocytes (called hypopion) 
 may also be seen. The iris adhering in any part 
 of the cornea is called an anterior synechia, and 
 adhesion of the iris to the anterior capsule of the 
 lens is called a posterior synechia. Vessels may 
 be seen on the surface of the cornea, as in pannus 
 and phlyctenular keratitis, and in the cornea itself 
 (interstitial keratitis). On the under surface of 
 the cornea may be seen small, brownish colored 
 dots (particles of lymph) arranged frequently in 
 the shape of a pyramid, with the apex upward 
 toward the pole of the cornea, and the base of the 
 pyramid downward ; this occurs in the disease known 
 as Descemetitis. Foreign substances, such as par- 
 ticles of iron, glass, powder grains, wood, etc., may 
 lodge in the aqueous. Entozoa have also been seen 
 in the aqueous. 
 
 The Iris. The anatomy of the iris may be 
 studied with the oblique light and magnifying lens 
 (Fig. 17), or, if there is inflammation or injury or 
 a foreign substance present, these may also be seen. 
 
132 THE OPHTHALMOSCOPE. 
 
 It will be well for the physician to make himself 
 thoroughly acquainted with the normal iris by 
 studying healthy eyes carefully with the oblique 
 light, and thus prepare himself for the prompt de- 
 tection of any departures from the normal, such as 
 unusual irregularities or growths, gummata, cysts, 
 tubercles, interpupillary membrane ( Fig. 62 ) , syne- 
 chia, causing irregular pupils, displaced pupils, or 
 polycoria. Inflammation of the iris is indicated by 
 a roughening of the iris, which gives it a velvety ap- 
 pearance. The apex of the light cone should be 
 passed slowly over the pupil and the reaction of the 
 iris to this stimulation should be carefully noted. 
 An excellent way to obtain the iris reaction is to 
 use the 5-volt lamp of the luminous ophthalmoscope 
 and as the patient fixes the lamp, to suddenly turn 
 on the electric current. 
 
 The Lens. To examine the lens satisfactorily 
 and as much of it as possible, it is well to have 
 the pupil wide open and to do this it will be neces- 
 sary to employ a mydriatic unless otherwise contra- 
 indicated. The lens has the same smoky appear- 
 ance as that which characterized the cornea under 
 examination, and the observer must examine it 
 carefully not only by the oblique illumination but 
 by the direct method before hastening to make a 
 diagnosis of a loss of transparency of this struc- 
 ture. Changes noted in the lens may be foreign 
 substances, injuries, anomalies, and any of the 
 various forms of cataract. 
 
OPACITIES OF THE LENS. 133 
 
 Opacities of the Lens and Its Capsule. On 
 
 the anterior capsule of the lens in the pupillary 
 area there is occasionally found one or more pig- 
 ment spots ; these pigment spots may not have any 
 particular position and in a few instances they are 
 seen to resemble a crescent, or they may form a 
 broken ring at the edge of the iris. These spots 
 are portions of iris pigment, and the result 
 usually of a previous inflammation of the iris. 
 Occasionally there is seen one or more fine mem- 
 branous brown shreds, passing from an attach- 
 ment to the anterior capsule of the lens (over the 
 pupillary edge of the iris) to the outer circle of the 
 iris; this is called an interpupillary membrane 
 (Fig. 62). Of course the more abundant these 
 shreds and the more the anterior pole of the lens 
 is obscured, the more the vision of the eye is im- 
 paired. In a study of opacities in the lens sub- 
 stance or capsules, it must be borne in mind that 
 with the oblique light the opacities appear more 
 or less gray in color with surrounding darkness, 
 whereas when studied with the reflected light from 
 the ophthalmoscopic mirror, they appear black 
 with a surrounding fundus reflex. 
 
 Anterior Polar Cataract. See Chapter III. 
 
 Posterior Polar Cataract. See Chapter III. 
 
 Lamellar, or Zonular, Cataract. See Chapter 
 III. 
 
 Nuclear Cataract (No. 4, Fig. 64), is an opacity 
 of the nucleus or center of the lens. 
 
134 THE OPHTHALMOSCOPE. 
 
 Cortical Cataract is the reverse of nuclear, 
 
 meaning opacity of the cortical portion of the lens. 
 
 This may be more or less complete, but usually it is 
 
 more conspicuous in the lower inner quadrant of 
 
 the lens, and in any instance it is diagnosed with the 
 
 ophthalmoscope by seeing dark spicules or striae 
 
 like needles pointing toward the center of the lens. 
 
 ~This is the most common form of beginning senile 
 
 ; cataract (No. 4, in Fig. 64). Cataracts are also 
 
 ; named from their causes. 
 
 Choroidal Cataract usually begins as a nuclear 
 cataract; it is brown in color and is the result of 
 choroidal disease; from its color and resemblance 
 to mahogany wood it has been called " mahogany 
 cataract." 
 
 Traumatic Cataract is a cataract caused by 
 injury. 
 
 *In the so-called Black Cataract the lens becomes 
 quite dark in color from absorption of or staining 
 by pigment. 
 
 Morgagnian Cataract is an over-ripe cataract. 
 The cortical substance has become fluid and the 
 nucleus remains hard and drops to the lower por- 
 tion of the lens capsule, which now resembles a 
 bag containing a milky fluid. The iris often ap- 
 pears tremulous. 
 
 Senile Cataract is the cataract of old age; a 
 better name would be hard cataract, or an opaque 
 sclerosed lens. Whenever partial opacity of the 
 lens is diagnosed it is wise to study the whole lens 
 
SUBLUXATION. 135 
 
 carefully, and also the interior of the eye, if the 
 opacity does not interfere too greatly with a view 
 of the eye ground, and to do this it will be necessary 
 to dilate the pupil with a solution of cocain (Chap- 
 ter I.). 
 
 Subluxation or Dislocation of the Lens. If the 
 ligament of the lens becomes relaxed or broken 
 partially or completely, the lens will become sub- 
 luxated or dislocated; in the former instance its 
 edge may be seen in the pupillary area; if dis- 
 located by force the lens may pass through 
 the pupil into the anterior chamber or fall 
 back into the vitreous. If the lens is in the 
 anterior chamber it can be easily recognized; 
 if in the vitreous or absent from the eye, and 
 the iris is not impaired, then its absence may 
 be recognized by a tremulousness of the iris 
 (iridodonesis). The iris having the aqueous in 
 front and back of it (the lens being out of posi- 
 tion) it naturally trembles or feels the wave motion \ 
 when the eye is suddenly rotated; this trembling 
 of the iris is also noted in Morgagnian cataract. 
 The absence of the lens can usually be diagnosed 
 by the greater depth of the anterior chamber, and 
 the tremulous iris and the refractive error, as meas- 
 ured by the strength of the glass required to see 
 the fundus. If the lens has been dislocated into the 
 vitreous it may be studied in its new position with 
 the ophthalmoscope, if there has not been too much 
 reaction resulting from irritation caused by the 
 
136 THE OPHTHALMOSCOPE. 
 
 lens. Partial dislocation of the lens, which brings 
 the edge of the lens into the pupillary area, may 
 be diagnosed by oblique light or with the ophthal- 
 moscope, the portion of the pupil without any lens 
 giving a different refractive estimate, when the 
 fundus is observed than the portion occupied by the 
 lens (see Ectopia lentis, Chapter III.). 
 
 The Vitreous Humor. Changes in the vitreous 
 indicative of disease, are loss of transparency in 
 parts (opacities) and diminished consistency. 
 Opacities of this medium may be from degenera- 
 tion of the substance itself or from hemorrhages 
 or exudates thrown off by the choroid or retina 
 or ciliary body or iris. Opacities of vitreous may 
 be caused by foreign bodies. Vitreous opacities 
 are of varying shapes and sizes, and may occupy 
 any portion of the vitreous. They may appear 
 black, brown or gray in color, or semi-transparent. 
 /They are variously described by the patient as 
 looking like different animals or fishes. They are 
 also spoken of as " motes " or " gnats in front of 
 the sight." These opacities may be quite station- 
 ary or freely mobile, depending greatly upon the 
 fluidity of the vitreous. Foreign substances, such 
 as pieces of glass, steel, iron filings or chips of 
 metal, etc., entering the eye, may carry air into 
 the vitreous, and this is recognized as bubbles look- 
 ing not unlike bubbles of air under the cover slide 
 in the field of the microscope. Foreign substances 
 reflect light from their edges, while air bubbles 
 
VITREOUS HUMOR. 
 
 reflect light from their centers. The path of the 
 foreign body as it passed through the vitreous is 
 occasionally recognized as a gray streak. 
 
 Opacities and changes in the vitreous may be 
 studied with the oblique or focal illumination, or 
 with the light reflected from the mirror at several 
 inches distant or with the mirror and a lens at the 
 sight-hole of the ophthalmoscope. It is only in 
 rare instances that the oblique illumination is used 
 for studying vitreous changes and the ophthalmo- 
 scope with a plus lens at the sight-hole is used by 
 preference. The lens in the ophthalmoscope which 
 gives a clear view of an opacity in the vitreous, gives 
 some idea as to its nearness to either the disc or pu- 
 pil, i. e., if seen with a strong lens, say a + 7 D., the 
 eye being emmetropic, this would indicate at once 
 that the opacity was well forward ; if the opacity was 
 seen with a + I D. it would therefore be well back 
 near the retina. If the observer is seated ten or 
 twelve inches from the eye and reflects the light into 
 it and an opacity is present and recognized, then if 
 the patient is told to rotate or turn his eye upward, 
 i the opacity will appear to move downward if the 
 I opacity is situated back of the plane of the iris, 
 but if the opacity is in the cornea or aqueous or an- 
 terior capsule of the lens, then it will appear to 
 move upward as the eye is turned upward; in 
 fact, it may be stated as a rule that all opacities 
 lying in front of the plane of the iris will move in 
 whatever direction the eye is turned or rotated, 
 
138 THE OPHTHALMOSCOPE. 
 
 and those opacities lying back of the plane of the 
 iris will appear to move in the opposite direction to 
 that in which the eye is rotated. This statement of 
 facts applies particularly to eyes with small or un- 
 dilated pupils, whereas eyes with large pupils give 
 a slight difference in the appearances, as the ob- 
 server is then able to see a trifle further back 
 into the eye and the center of rotation appears 
 beyond the plane of the iris. The normal center 
 
 FIG. 65. To DETERMINE THE POSITION OF A FIXED OPACITY IN THE 
 
 EYE. (Jennings.) 
 
 In the upper drawing is shown an opacity on the cornea at a, one on 
 the anterior surface of the lens at b, and one on the posterior surface 
 at c. Looking into the eye, these three opacities appear as one black 
 point in the center of the pupil. If the patient is now requested to 
 look down, three black points appear, c moves upward, b remains sta- 
 tionary, and a moves downward. 
 
 of rotation lies back of the lens about 10 milli- 
 meters from the disc. However, when the opacity 
 lies very near the plane of the iris it is apparently 
 so stationary when the eye is rotated that it is often 
 necessary to employ the oblique light to make a 
 
CHOLESTERIN CRYSTALS. 139 
 
 positive diagnosis of its exact location. Figure 65 
 explains the description just given. New growths 
 are occasionally seen in the vitreous, such as cysts, 
 proliferations from the retina (retinitis prolifer- 
 ans) and also entozoa, the cysticercus cellulosae and 
 filaria. These latter have been seen in the cornea, 
 iris and lens, but their most common location is 
 between the choroid and retina. 
 
 Foreign bodies in the vitreous may be recog- 
 nized if seen quite early, but after a few hours the 
 vitreous surrounding them usually becomes more 
 or less cloudy. Vitreous opacities when they move 
 freely by slight rotation of the eye, become very 
 annoying to some patients, and at times cause hal- 
 lucinations. 
 
 Cholesterin Crystals (synchysis scintillans, 
 sparkling synchysis; synchysis etincelant) are seen 
 at times in the vitreous humor, and give a most 
 beautiful pyrotechnic display when seen with the 
 ophthalmoscope. Each crystal reflects the light, 
 giving the appearance of a shower of gold. It is a 
 rare condition before the age of fifty. There is 
 no cure for this condition. It may appear in one 
 eye alone or in both. 
 
CHAPTER VI. 
 
 VISUAL ACUITY. FIELD OF VISION. PERIMETRY. 
 
 IN connection with the ophthalmoscopic findings 
 of pathologic changes, the physician should be 
 ready to make a record of the visual acuity and the 
 field of vision of each eye, as these two records will 
 often aid him materially in a correct diagnosis and 
 prognosis. 
 
 Visual Acuity. This is generally understood 
 and spoken of as central or direct vision, and 
 
 the part of the retina 
 concerned is the fovea 
 centralis. When an 
 eye looks at an ob- 
 ject and the image is 
 formed at the fovea 
 centralis, the eye is 
 said to " fix " the ob- 
 ject. Visuaf acuity may 
 be defined as the see- 
 ing quality of the eye 
 without glasses. The 
 standard visual acuity is 
 the power of the eye to 
 distinguish letters and characters occupying an 
 angle of five minutes. Such letters and characters 
 
 140 
 
 c 
 
 E 
 
 C P 
 
 C P 
 
 in 
 
 A L 
 
 tn 
 
 L A 
 
 G Y"D T 
 
 V F H U A 
 
 T G~Y D 
 
 F A V H U 
 
 L E C H D O 
 CEO R~L C P A 
 
 D L O E C N 
 C P A R'C E O L 
 
 FIG. 66. Randall's Test-letters. 
 Block letters on black or cream- 
 colored cards. 
 
VISUAL ACUITY. 
 
 141 
 
 in black are engraved on a cream-colored card, or 
 white letters on a black card are shown in Figs. 66, 
 67, 68. These cards uniformly illuminated are 
 placed 20 feet (six meters) from the patient and 
 each eye 'is tested separately by covering its fel- 
 low. The patient pronounces __ 
 the letters or if illiterate he 
 tells the direction in which the 
 arms of the E are pointed. 
 f The lowest line of letters or 
 characters which the eye can 
 recognize distinctly, is the vis- 
 ual acuity of that eye and it is 
 recorded in the form of a frac- 
 tion, the numerator of the 
 fraction being the distance 
 of the eye from the card and 
 the denominator being the size 
 of the letters distinguished. 
 For the guidance of the 
 physician each line of letters 
 or characters, is marked in 
 small roman characters which 
 tell him at once the dis- 
 tance (in feet or meters) at which such letters or 
 characters should be read by the standard or emme- 
 tropic eye. The standard visual acuity would be 
 the line of letters marked 20 feet or 6 meters 
 which should be read with ease at the distance of 
 20 feet. If the eye cannot see or recognize the 
 
 FIG. 67. Gould's Test- 
 ^ Goth h j c [ etters H in 
 
 white on a black card. 
 
III 
 
 
 142 THE OPHTHALMOSCOPE. 
 
 top letter on the test card at the distance of 20 
 feet, then the distance must be shortened by bring- 
 ing the card slowly toward the patient or letting 
 the patient approach the card un- 
 B I til he is able to recognize the letter 
 
 S j>L 1 distinctly. 
 
 Peripheral Vision. This is 
 known and spoken of as indirect 
 vision or the visual field, and the 
 
 part or parts of the retina con- 
 ^~ III H 
 
 & *** l3 cerned lie more or less remote 
 
 E 3 UJ n from the fovea centralis. The 
 
 fovea centralis represents the 
 u 3 E m m 
 
 most acute vision and peripheral 
 
 u m E u 3 E 
 
 or indirect vision is much less 
 
 FIG. 68. illiterate acute and therefore not so easily 
 
 Card. obtained as the direct. Indirect 
 
 vision diminishes or becomes much 
 
 more indistinct as the outermost limits of the retina 
 
 are brought into use. 
 
 To Test Peripheral or Indirect Vision. Each 
 eye must be examined separately as in testing cen- 
 tral or direct vision, i. e., keeping the eye covered 
 which is not being tested. Testing peripheral 
 vision is known as perimetry, and an instrument 
 known as the perimeter is generally employed for 
 exact work (Fig. 69). With this instrument on 
 a convenient table and the patient comfortably 
 seated, his chin is placed on a rest and the eye to 
 be tested is opposite to, and 13 inches from, a round 
 
PERIPHERAL VISION. 
 
 white disc 10 millimeters in diameter, fixed in the 
 center of a semicircle. As the eye fixes the disc 
 the physician at the back of the perimeter watches 
 the patient's eye that it remains fixed during each 
 step of the examination. Then with either of his 
 
 FIG. 69. McHardy's Perimeter. 
 
 hands the physician revolves the milled wheel at 
 the back of the semicircle and thereby a carrier is 
 made to travel along the inner side of the semi- 
 circle by means of pulley and cord. This carrier 
 contains a disc with various colors upon it and any 
 one of these colors may be exposed to most any 
 convenient size as the physician may select. A 
 field chart or blank (Fig. 70) is placed in the 
 bracket attached to the back of the perimeter. 
 There is a small steel needle at the back of the 
 semicircle near the milled wheel. The semicircle 
 
144 
 
 THE OPHTHALMOSCOPE. 
 
 will take any meridian in which the physician 
 wished to place it by merely pressing it with his 
 hand. The inner surface of the semicircle should 
 always be uniformly illuminated. The physician 
 usually places the carrier with its selected color one 
 centimeter in size, at the extreme end of the semi- 
 
 FIG. 70. Field charts for Right and Left Eye. 
 
 circle and gradually brings it toward the center on 
 which the patient is fixing. As the carrier with 
 its .exposed color is brought toward the center (by 
 the physician turning the milled wheel) the patient 
 is instructed to tell as soon as the peripheral object 
 comes into view. When this is mentioned the phy- 
 sician stops turning the wheel and presses the 
 chart against the steel needle, which makes a punc- 
 ture at a point in the chart corresponding to the de- 
 gree mark on the semicircle. In this way the various 
 meridians are recorded on the chart. Usually they 
 
PERIPHERAL VISION. 145 
 
 are 15 degrees apart, though they may be made closer 
 if desired. After the meridians have been recorded 
 the physician connects the individual points with 
 straight lines, using pencil or pen, and these con- 
 nected points represent the outermost limit of 
 vision. The record is made in the same way for 
 the various colors. That for white is spoken of 
 as the form field. 
 
 The peripheral field is naturally reduced in the 
 direction of the overhanging brow and in the di- 
 rection of the nose, and therefore it is not so re- 
 stricted downward and outward. 
 
 If a perimeter is not at hand for recording 
 peripheral vision the record may be made upon a 
 blackboard, but it must be remembered that the 
 record thus obtained upon a plane surface is quite 
 different from the perimetric findings. An ex- 
 cellent method and one always at hand for making 
 an approximate test, is for the physician to sit 
 facing the patient so that their eyes are about 26 
 inches apart. The patient closes the eye not being 
 tested and the physician closes his eye that is di- 
 rectly opposite to the one the patient closes, or the 
 physician keeps his right eye open when testing the 
 patient's left eye, and vice versa. In this position 
 with the eye of the physician and patient fixing 
 each the other, the physician uses the end of a black 
 lead pencil or a black pen holder as a finder, the end 
 of the finder having a small piece of white paper a 
 quarter of an inch wide wrapped around it. The 
 
146 THE OPHTHALMOSCOPE. 
 
 physician moves this finder inward from arm's 
 length midway between his and the patient's eye. 
 The physician's peripheral vision being normal, he 
 will know at once when the patient's eye should 
 recognize the white paper. Colored papers may be 
 used in the same way. The end of the handle of 
 the Morton ophthalmoscope is adapted admirably 
 for this purpose. The field of vision taken in 
 this way is not exact, neither can it be exactly re- 
 corded, but it is often most suggestive and of great 
 value, until a careful perimetric tracing can be made 
 later. The normal peripheral field, while of the 
 same outline as the chart, is not the same size for all 
 colors; that for white (or form) is the outermost 
 and largest, then comes blue, then red and then 
 green. The field of vision may also be taken with 
 two lighted candles in a dark room. One candle is 
 held in front of the eye, and the other candle is car- 
 ried through the various meridians. This is known 
 as the candle field. This is not exact. It is merely 
 suggestive. 
 
 Scotoma (O-KOTO?, darkness). The one spot in 
 the field of vision which does not see and is therefore 
 normally blind, is called the physiologic blind spot, 
 or Mariotte's blind spot, and is situated about i_ 
 degrees to the outside of the point of fixation (o 
 in Fig. 70), this corresponds to the entrance of the 
 optic nerve. Scotomata are recognized when the 
 field of vision contains areas or spaces which are 
 defective in their normal seeing quality or con- 
 
SCOTOMA. 147 
 
 tracted or distorted in outline by certain diseases of 
 the eye itself and also by various general diseases. 
 
 Concentric contraction of the field of vision is a 
 form of scotoma, in which peripheral vision is re- 
 duced in size in all meridians, depending upon the 
 stage of the disease in which this condition is 
 found. 
 
 The size of the normal field is shown in Fig. 70. 
 The field of vision may be cut off in quadrants or 
 sectors or halves ; this latter is spoken of as " hemi- 
 anopic " or half field. In making the test for 
 scotoma the test object must be quite small, 2 to 4 
 millimeters in size. 
 
 Central Scotoma. This indicates the loss of 
 good central vision, it may be partial or complete, 
 and is found in macular diseases from syphilis, 
 myopia, and from toxic amblyopia, etc. Scotomata 
 are also classed as paracentral, peripheral and ring. 
 
 A scotoma is said to be positive when the patient 
 is conscious of a dark area in his field. A scotoma 
 is said to be negative when the patient has a sco- 
 toma and is not conscious of its presence. A nega- 
 tive scotoma may be absolute or relative, the for- 
 mer when white and colors cannot be recognized 
 and the latter (relative) when the light sense is 
 diminished. Frequent reference to visual acuity 
 and the field of vision will be made in the considera- 
 tion of ophthalmoscopy. 
 
CHAPTER VII. 
 
 RETINAL VESSELS. HEMORRHAGES. PIGMENT CHANGES. 
 HYPEREMIA. ANEMIA. EMBOLISM. THROMBOSIS. 
 
 The Retinal Vessels. Pressure upon the nor- 
 mal eyeball with the end of the finger, while the 
 observer views the retinal vessels, will show an 
 impediment to the blood current entering and leav- 
 ing the eye and with the result that the blood is 
 held in the retinal vessels. Great pressure, if the 
 subject will tolerate it, shows an entire emptying 
 of the vessels on the disc. The light streak in the 
 vessels is consistently diminished or absent, accord- 
 ing to the amount of pressure, and the length of 
 time the pressure is maintained. Great pressure 
 may blanch the disc to a distinct whiteness from 
 its normal color. The statement that the nor- 
 mal proportion in size between arteries and veins 
 is as two to three is particularly true of the vessels 
 in the retina, but it is not true of the vessels on the 
 disc, which may appear to grow narrow or re- 
 stricted and quite frequently a vein on the disc may 
 appear abnormally large. However, any great in- 
 crease or diminution in the size or breadth of a 
 vessel or part of a vessel in the eye ground, aside 
 from the disc is quite indicative of disease; for 
 instance, arteries and veins may both be increased 
 
 148 
 
THE RETINAL VESSELS. 149 
 
 in diameter or the arteries may remain normal and 
 the veins diminish, or, what is much more usual, 
 the veins may become greatly increased in width. 
 Changes in the retinal vessels are not always easily 
 detected unless the condition is well marked or care- 
 fully loc Jted for, simply because there are normally 
 many differences, and it is therefore good practice 
 to compare the size of the vessels in the two eyes. 
 This careful comparison will at least make a diag- 
 nosis of a systemic condition, as compared with a 
 local manifestation. The fact must also be borne in 
 mind, that there is an occasional exception to this 
 comparison of relative size between arteries and 
 veins when there happens to be two veins accom- 
 panying an artery, or two arteries accompanying 
 a vein. 
 
 Increase in Diameter of Veins. These are usu- 
 ally seen in inflammation of the retina where the 
 disc is also involved, and at the same time the 
 veins may become tortuous, while the arteries are 
 diminished in size. This increase in the diameter 
 of the veins may be limited to only a few of the 
 veins or possibly the increase affects but one vein 
 or a part of a vein, and is due to an inflammation 
 involving the vessel walls or to pressure on the 
 venous trunk in the membrana cribrosa, or after 
 it leaves the eye, or it may be due to some general 
 venous congestion. Veins increased in diameter 
 (beyond the normal size) are seen in specific and 
 splenic retinitis, and in fact in nearly all varie- 
 
I5O THE OPHTHALMOSCOPE. 
 
 ties of retinitis; the early stages of fever, such as 
 typhoid; also in pleurisy, pneumonia, asthma, and 
 in congestion and inflammation of the brain or its 
 meninges; in various forms of heart disease and 
 anemia. Any impediment to the return blood 
 stream from the eye will naturally cause the veins 
 to become distended, and this is seen to be the case 
 in such diseases of the eye as glaucoma and oplis 
 nejjritis, and undue pressure on the venous trunk 
 between the eye and the heart, as in diseases of 
 the orbit, erysipelas, cellulitis, growths, etc.; and 
 pressure in the neck from goitre and various 
 growths ; and in various diseases of the lungs, espe- 
 cially phthisis. 
 
 Decrease in Diameter of the Veins. This con- 
 dition of the veins is not at all common, and when 
 seen is usually a condition or disease of the eye 
 itself, such as atrophy of the retina or optic nerve. 
 In embolism of the central artery the veins in some 
 portions are quite narrow. The diameter of the 
 vein decreases in degeneration of the vessel itself. 
 
 Increase in Diameter of the Arteries. This 
 condition, like diminution in the size of the veins, 
 is very rare indeed, and when recognized is usu- 
 ally caused by some disease of the coats of the 
 artery which has weakened its contractile power, 
 and yet this condition may be seen when the heart 
 action is increased; also in early stages of fever, 
 pneumonia, pleurisy, brain disease and leukemic 
 retinitis. 
 
DIAMETER OF ARTERIES. 
 
 Decrease in the Diameter of the Arteries. 
 
 This condition of the arteries is much more com- 
 mon than an increase in their size. Intra-ocular 
 pressure which keeps the blood from entering the 
 eye as freely as it otherwise would, will cause a 
 diminution in the size of the arteries; therefore, a 
 decrease in the diameter of the arteries is seen in 
 glaucoma, embolism, papillitis, thrombosis, hemor- 
 rhagic retinitis, etc. Optic and retinal atrophy fol- 
 lowing inflammation leaves the arteries not only di- 
 minished in calibre but also with a white line seen 
 in the vessel for a considerable distance from the 
 disc; this is due to sclerosis of the middle coat of 
 the artery and this whitening of the coat may be 
 sufficiently dense to obscure any view of the blood 
 stream, the artery or arteries looking like white 
 threads or cords. The arteries are seen to be di- 
 minished in size in conditions resulting from weak 
 heart, also anemia and chlorosis, epilepsy, etc. Reti- 
 nitis pigmentosa causes a diminution in size of 
 both arteries and veins. A thickening in the 
 arterial coats and a diminution in the calibre of 
 the arteries results in albuminunc_retinitis. 
 
 Changes in Vessel Walls Arteriosclerosis. 
 These may be designated as fatty degeneration, 
 chalky deposits, perivasculitis and sclerosis; the 
 arteries are unevenly narrowed or the arteries may 
 be bordered by extravasations, and the veins may 
 be distended, showing many narrowings or con- 
 strictions like the arteries. These conditions are 
 
152 THE OPHTHALMOSCOPE. 
 
 usually recognized with the ophthalmoscope by 
 diminution in the normal transparency of the ves- 
 sel walls. The vessel walls having their lumen di- 
 minished will naturally reveal this condition, when- 
 ever there is any crossing over of the vessels as the 
 blood current is diminished at this crossing, if there 
 is any pressure exerted, and then the vessel again 
 refills after the crossing (Plates VI. and X.). One 
 vessel or a part of a vessel, or all the vessels, may 
 be affected by these changes. Sclerosis of the 
 vessels is quite conspicuous in retinitis pig- 
 mentosa, whether of the congenital or acquired 
 (specific) variety. Sclerosis of the vessels may be 
 seen in any form of retinitis, but especially in the 
 nephritic variety. 
 
 Perivasculitis. This is an increase or a hyper- 
 plasia of the connective tissue about the vessels, 
 principally and usually the arteries (periarteritis) 
 (Plate IV.). The condition is recognized with 
 the ophthalmoscope by the yellowish-white color of 
 the vessels, which appear in some instances, when 
 inflammation and proliferation is excessive, to look 
 like white threads. If the inflammation is not so 
 severe the sides of the vessels appear to have a 
 yellowish-white color, or the vessels appear to be 
 bordered with delicate or narrow white lines, seen 
 in eyes having post-papillitic atrophy or atrophy of 
 the retina. 
 
 Vessels of New Formation in the Retina. 
 These are very rare indeed and when present are 
 
RETINITIS PROLIFERANS. 153 
 
 seen to run in the same direction usually as the 
 large vessels; they appear in isolated areas and a 
 common position is on, or near, the disc. They 
 maintain about the same caliber throughout, with 
 very little, if any, diminution in size, and are often 
 quite tortuous, and on this account have been de- 
 scribed as " cork screw." Growths in the choroid 
 and retina may show vessels of new formation. 
 
 Vessels of New Formation in the Vitreous 
 (Retinitis Prolif erans) . Like vessels of new for- 
 mation in the retina, these form a very rare condi- 
 tion, and from the same cause presumably, viz., 
 some severe inflammation of the retina in which 
 the connective tissue about the retinal vessels, or 
 a single retinal vessel, has become vascularized. 
 During this severe inflammation of the retina no 
 distinct view of the eye ground can be made out, 
 but when this inflammation subsides these newly 
 formed vessels, supported by connective tissue, 
 may be recognized extending across the fundus 
 and into the vitreous, resembling bands with many 
 fine loops of vessels of varying length, and occa- 
 sionally these vessels appear like strands of rav- 
 elled thread. Vessels of new formation are ap- 
 parently venous. 
 
 Aneurisms, or Varicosities, or Dilatations of 
 the Retinal Vessels. These are rare conditions, 
 and may be congenital or caused by trauma or in- 
 flammation. A dilation of a retinal vein on the disc 
 is not uncommon but has erroneously been spoken 
 
154 THE OPHTHALMOSCOPE. 
 
 of as an aneurism. An aneurism of a retinal artery 
 would be recognized by its more or less rounded 
 shape in the course of the artery, resembling a bead 
 on a string or thread, the light streak in the vessel 
 being interrupted at the aneurism. 
 
 Arterial Pulsation. This is not a common con- 
 dition, and when present is usually pathologic; if 
 seen extending well into the retina beyond the 
 disc it usually signifies aortic valvular disease (in- 
 sufficiency). Pulsation of the arteries on the disc 
 is most commonly seen in glaucoma, a point in diag- 
 nosis in this disease. 
 
 Owing to the position of the retinal vessels be- 
 tween, the choroid and the vitreous, they naturally 
 receive pressure from the front, and the back, and 
 on this account they are found to be oval on sec- 
 tion, the horizontal diameter being greater than 
 the perpendicular. If the retinal vessels are dis- 
 tended they naturally approximate a circular 
 shape; hence the broader the light streak, the flat- 
 ter the vessel, and vice versa. 
 
 Venous Pulsation. This is not necessarily path- 
 ologic; on the contrary, it is normal in most cases 
 when seen upon the disc or extending a short dis- 
 tance into the retina (see Chapter IV.). It may 
 be seen with an increase of intra-ocular tension. 
 
 Hemorrhages. There is no portion of the 
 retina which may be considered exempt from the 
 presence of hemorrhages, and these may occur 
 in any layer or in any portion of its surface. Hem- 
 
HEMORRHAGES. 156 
 
 orrhages from the retinal vessels vary in their 
 color, shape, size and location. Most hemorrhages 
 at the time of their occurrence are darker than the 
 general f undus reflex, being bright red, and later be- 
 come darker in color, and may disappear by absorp- 
 tion of the clot, and no evidence of their previous 
 existence will be recognized; yet occasionally some 
 pigment may appear after the hemorrhage has been 
 absorbed, but this is rare. A very profuse hemor- 
 rhage may leave its mark by the presence of 
 spots of a brownish or brownish-black color. As 
 a rupture of a retinal vessel only takes place by 
 violence, hemorrhages in the retina from disease 
 must take place by the escape of blood through 
 the vessel walls. A very natural inference in re- 
 gard to hemorrhages in the retina, as elsewhere, 
 would be that they would occur in the periphery of 
 the eye ground where the vessels are small and pre- 
 sumably weaker, but while this is undoubtedly good 
 reasoning, yet the very reverse is the case; the 
 hemorrhages occurring from the large vessels 
 whose walls cannot resist the pressure, which pres- 
 sure is very likely much greater in the large ves- 
 sels than in the small ones; in other words, the 
 walls of the smaller vessels must be stronger or the 
 pressure is less by the time the blood stream gets 
 to them, or both conditions may exist. With this 
 understanding of the vessels affected, it will be bet- 
 ter appreciated why the most common seat of reti- 
 nal hemorrhages is at the disc and its immediate 
 
15'-> THE OPHTHALMOSCOPE. 
 
 neighborhood. The next most common situation 
 for the presence of retinal hemorrhages is at the 
 macular region, and naturally hemorrhages at the 
 macula obscure vision more and more as the fovea 
 centralis is encroached upon. Hemorrhages in the 
 periphery are of capillary origin and have this sig- 
 nificance, that the morbid process is either in the 
 capillary vessel walls, or if in the large vessels also 
 it is the small vessels which are mostly affected, 
 and usually this means a grave general disease and 
 is much more significant, if the hemorrhages are 
 in the deep layers of the retina. 
 
 Shape, Size and Location. Hemorrhages in 
 the nerve fiber layer (inner layers) of the retina, 
 appear more or less streaked, having rather 
 straight edges or sides, and their ends, especially 
 the distal ends, resemble the edge of a feather or 
 gas flame, and are therefore commonly described 
 as " feathered edged " or " flame-shaped." The 
 cause of this peculiar striation is that the blood 
 works its way between the nerve fibers, which ap- 
 pear to cut it into fine lines (Plates V. and VI.). 
 Hemorrhages in the deep layers (outer layers) of 
 the retina are not so characteristically marked but 
 appear as small red dots, round or irregularly 
 shaped (Plate VI.). Hemorrhages between the 
 retina and the choroid may appear round or oval 
 with sharp cut edges; the retinal vessels may be 
 seen passing over such hemorrhages, which would 
 indicate at once that the hemorrhage must be back 
 
HEMORRHAGES. 1 5 7 
 
 of the retina, and of course the retina must be more 
 or less elevated at the location of the hemorrhage. 
 A hemorrhage between the retina and the vitreous 
 called a subhyaloid hemorrhage, has a circular 
 shape and sharp edges, and naturally such a hem- 
 orrhage obscures any view of the retinal vessel be- 
 hind it. A subhyaloid hemorrhage may have its 
 upper edge quite straight and its lower edge a con- 
 vexity downward ; this is due to the blood settling by 
 gravity. Retinal hemorrhages may appear isolated 
 without any apparent connection with vessels, but 
 usually they lie near the vessels. A retinal hemor- 
 rhage may be so large that it will break through 
 the hyaloid membrane and escape into the vitreous, 
 and in this way it is a frequent cause of vitreous 
 opacities. 
 
 Causes of Retinal Hemorrhages. Retinal 
 hemorrhages may be caused by over-distension of 
 the vessel, or degeneration of the vessel wall, by 
 alteration of the blood itself, and occasionally by 
 injury; all inflammatory diseases of the retina 
 itself; increased heart action; abnormal and sud- 
 den suppression of the menses; diseases of the 
 brain, kidneys and spleen; diabetes; pernicious 
 anemia, leukemia; gout; tuberculosis; scrofula; 
 purpura; hemorrhagic diathesis; degeneration of 
 vessel walls; thrombosis and embolism; injuries; 
 etc. 
 
 Changes in the Vascularity of the Retina. 
 These may be many or few; they may be limited 
 
158 THE OPHTHALMOSCOPE. 
 
 to several vessels or to a single vessel, or a part 
 of a vessel. As an extreme condition of pallor or 
 diminution of the blood supply to the retina, may 
 be mentioned embolism of the central artery (Plate 
 II.); and as the extreme condition of engorge- 
 ment of the retina may be mentioned thrombosis 
 of the central vein (Plate III.). 
 
 Pigment Changes. Normal pigmentation more 
 or less extensive may be seen at the choroidal ring 
 in almost every eye (Plate I.) and occasionally an 
 innocent amount of pigment may be seen in a small 
 mass at the upper edge of the disc, and not infre- 
 quently a small round spot of pigment the size of 
 a pin head, or a trifle larger, may be seen at some 
 distant point in the retina where it is not of any 
 serious consequence (Plate VIII.), and yet each 
 spot of pigment, wherever situated, should have 
 careful consideration. Scattered areas of pig- 
 mentation should always be looked upon with sus- 
 picion, especially those connected with changes in 
 the choroidal coat (Plate XL) and those seen upon 
 the retinal vessels. 
 
 Hyperemia of the Retina. It is not an easy 
 matter for the beginner in ophthalmoscopy, to ap- 
 preciate this characteristic condition of the eye 
 ground, and yet it is a most important one, and one 
 often overlooked, if the observer is not extremely 
 cautious. Overlooked in the sense that it may be 
 so well marked as to suggest a beginning retinitis 
 or papillitis; however, the patient's history, etc., 
 
IIYPEREMIA OF RETINA. 159 
 
 will surely put the observer on his guard. Hyper- 
 emia of the retina is manifest principally upon the 
 disc and its immediate neighborhood by a conges- 
 tion of the retinal capillary vessels which lie in the 
 most anterior layers of the retina, and as these 
 vessels are not ordinarily prominent in healthy 
 eyes, their congestion will give the retina a striped 
 appearance about the nerve, and its edges will be- 
 come somewhat obscure or " wgolly." The nerve 
 (intermediate zone) may have a red brick dust 
 color. The macular region, if carefully observed, 
 will appear of a much darker hue than is consistent 
 or in keeping with the general appearance of an 
 otherwise quiet eye. This hyperemia of the 
 retina, described by Jaeger as " irritation of the 
 retina." is the unique picture often seen in eyes 
 with refractive errors, especially of the hyperopic 
 (hypermetropic) variety. As nearly 80 per cent. 
 of all eyes have some form of hyperopia, then, 
 as just stated, " irritation of the retina " is not such 
 an uncommon condition, especially if the eyes have 
 not been " glassed," or if the glasses are not correct. 
 Retinal irritation as just described is brought 
 /about therefore by accommodative effort and the 
 1 condition is recognized as a disease and called ac- 
 \commodative asthenopia. The symptoms are in 
 keeping with the irritated and fatigued retina and 
 ciliary muscle, though the vision is not as much at 
 variance as might be expected by the refractive er- 
 ror present; the patient, however, complains of his 
 
l6O THE OPHTHALMOSCOPE. 
 
 eyes feeling tired, the eyeballs ache, blurred vision 
 comes on after prolonged near work, or after a time 
 this blurred vision may come on promptly after using 
 the eyes for only a few minutes, while looking atten- 
 tively at any nearby object. With the blurred vision 
 there is often a dread of light (photophobia). 
 Frontal headache (brow ache) over both eyes or 
 over one more than its fellow, usually over the eye 
 with the least refractive error. The frontal head- 
 ache may extend into the temples, a temporal head- 
 ache, and nausea and dizziness may also be present. 
 If the patient forcibly concentrates his vision, the 
 object looked at may soon appear unsteady or in- 
 distinct, and then the eyes may become suffused with 
 the lacrimal fluid. The treatment is rest with a 
 cycloplegic and dark glasses, and carefully selected 
 glasses, the eyes being made equal to the emmetropic 
 or standard condition, which is a minimum amount 
 of accommodative effort for the work at which the 
 eyes are engaged. 
 
 RETINAL IRRITATION, OR HYPEREMIA, FROM EXPOSURE 
 OF THE EYES TO SUNLIGHT (SOLAR RETINITIS); TO 
 ELECTRIC LIGHT AND FLASHES OF ELECTRIC LIGHT 
 (ELECTRIC RETINITIS); TO REFLECTION FROM THE 
 SNOW (SNOW BLINDNESS). 
 
 The symptoms of these conditions are, photo- 
 phobia and lacrimation with irritation of the con- 
 junctiva. The patient's history gives the cause. 
 Sun blindness and snow blindness usually re- 
 cover after the use of dark glasses for a few days 
 unless the condition is complicated by conjunc- 
 
ANEMIA OF RETINA. l6l 
 
 tivitis and ulcer of the cornea or macular changes, 
 when appropriate treatment for these compli- 
 cations must be met. Electric retinitis is a much 
 more serious matter, for when the exposure has 
 been a lengthy one, or the electric flash has 
 been intense, there may be extensive changes 
 set up in the macula and macular region of a low 
 grade retino-choroiditis, which may leave per- 
 manent changes and damage to central vision. The 
 treatment for such cases is rest of the eyes with 
 dark glasses and restraint from any use of the eyes 
 whatever until fully recovered. It may be neces- 
 sary to institute internal medication, and to use a 
 solution of atropin in the eyes for a few days. If 
 snow blindness is complicated with changes in the 
 macula, then a similar line of treatment must be 
 carried out. 
 
 Anemia of the Retina. This is the reverse of 
 hyperemia and therefore gives something of a re- 
 verse picture, and the striations at the disc edges are 
 absent. The disc is pale and the general fundus re- 
 flex is lighter in color than normal. The arteries 
 are not distended, and if compression or embolism 
 of the central artery is present, the picture of 
 anemia of the retina is typical (Plate II.). The 
 ophthalmoscope reveals diminished amount of blood 
 in retinal vessels by the absence of the light streak, 
 which, if present at all is very narrow and does not 
 extend far into the eye ground. The veins and 
 arteries are equally affected. There are exceptions 
 
1 62 THE OPHTHALMOSCOPE. 
 
 to this broad statement and the arteries may be 
 small and veins large. Naturally the eye ground in 
 anemia appears paler than normal and the pale 
 condition is in keeping with the light color of the 
 disc, so that the line of demarkation between disc 
 and surrounding eye ground, is not always very 
 well marked. This condition must not be con- 
 founded with optic atrophy where the contrast is 
 very marked, but in the beginning of optic atrophy 
 the contrast is not so conspicuous. Systemic 
 anemia from any cause will often express itself in 
 anemia of the retina, but a pale face does not neces- 
 sarily mean anemia of the retina, nor does a florid 
 complexion necessarily mean hyperemia of the 
 retina. While admitting that a patient's color may 
 be an index of his blood condition, yet a pale com- 
 plexion may be due to a want of blood in the capil- 
 laries of the skin and no change be noted in the 
 retina, and a florid complexion may mean blood in 
 the capillaries of the face, and yet the system be 
 anemic, as indicated by the retina. 
 
 Differential Diagnosis, as Revealed with the 
 Ophthalmoscope between Pallor of the Disc and 
 Retina in Anemia and that Caused by Optic 
 Atrophy. 
 
 Anemia. Atrophy (Plate X.). 
 
 Pallor of disc. White disc. 
 
 Surrounding eye ground also Surrounding eye ground appears 
 pale. redder than normal. 
 
PLATE II. 
 
 EMBOLISM OF THE CENTRAL ARTERY OF THE LEFT EYE. DIRECT 
 METHOD. 
 
 S. B. Male. Aged 61 years. 
 
 History. Embolism came without any warning in a man other- 
 wise apparently well. (Two years later, without apparent cause, a 
 large hemorrhage took place in this same eye, followed by iritis, a 
 dislocation of the lens into the vitreous and the development of 
 absolute glaucoma requiring enucleation.) Large, oval-shaped, 
 blanched area, which includes the disc and macula. Cherry-red spot 
 at the macula. Intermediate zone of the disc shows apparently 
 normal except for a faint fogginess. The arteries are almost empty 
 and the smaller ones have the blood stream broken in different 
 places. The arteries have lost their light streak. The veins are 
 slightly distended, but not tortuous; the light streak is almost lost 
 in the veins, but can be faintly seen. 
 
 164 
 
PLATE II 
 
 Embolism of the Central Rrtzrij 
 
PERNICIOUS ANEMIA. 1 67 
 
 Anemia. Atrophy (Plate X.). 
 
 Relative size of arteries and Arteries smaller and in late 
 
 veins remains about the same, stage of atrophy are reduced 
 
 vessels may not be uniformly in number. In early stage 
 
 filled. veins are larger. In late stage 
 
 veins are diminished, and not 
 readily distinguished from ar- 
 teries. 
 
 Disc surface not sunken. Disc surface in late stage is 
 
 sunken, becoming concave or 
 saucer shaped. 
 
 Pallor due to want of blood and Pallor due to shrunken capil- 
 hence capillaries in the disc do laries in disc and also increase 
 not appear. of connective tissue. 
 
 Causes of Anemia. Fainting and loss of blood 
 and general anemia will cause pallor of the retina 
 and disc. Pallor of the retina and disc is also seen 
 in true migraine and may also be caused temporarily 
 by toxic doses of quinine and salicylic acid. 
 
 Treatment. Iron and arsenic, etc., for the gen- 
 eral anemia; appropriate treatment for the weak 
 heart. 
 
 Pernicious Anemia. The retina in pernicious 
 anemia is not actively inflamed. The disc appears 
 pale and the edges woolly, so that the retina and 
 disc are not separated by any sharp line. The eye 
 ground appears of a yellowish cast. Small hemor- 
 rhages appear in the nerve fiber layer and are there- 
 fore flame-shaped. Hemorrhages in pernicious 
 anemia are not a constant condition. This condi- 
 tion of the retina is also seen in hemophilia, purpura, 
 malaria, scurvy (scorbutic anemia), etc. 
 
 Embolism or Thrombosis of Central Artery of 
 the Retina (Plate II.). When there is complete 
 
1 68 THE OPHTHALMOSCOPE. 
 
 occlusion of the central artery of the retina (if 
 seen shortly after the plugging has taken place) 
 then the following changes will be observed: 
 
 1. Change in Arteries. The large vessels are re- 
 duced to white lines, appearing like white threads, 
 and the small arteries cannot be seen. Here and 
 there in an artery may be seen some portion of 
 the blood stream broken into sections. 
 
 2. Changes in Veins. These may be normal but 
 usually they are contracted and show irregularities. 
 
 3. Changes in Disc. The disc appears pale as the 
 capillaries are not distended. 
 
 4. Changes in Retina. The central portion of 
 this structure is swollen or edematous and grayish- 
 white in color, embracing the macula and disc, giv- 
 ing the appearance of a large horizontally oval area 
 of edema. The peripheral portion of the retina is 
 not similarly involved. Many small hemorrhages 
 may be present. A cherry red spot occupies the 
 fovea, resembling a round hemorrhage. This 
 cherry red spot is caused by the red of the cho- 
 roid appearing through the retina at the macula. 
 
 Embolism affecting a branch of the central 
 artery gives a picture of changes consistent with 
 the retina correspondingly affected, but the 
 cherry red spot may not be present. The dilated 
 vessel up to the point of plugging may be distinctly 
 seen and the remainder of the vessel lie empty, look- 
 ing like a white thread or containing sections of the 
 blood stream. Several weeks after the embolus 
 
EMBOLISM OF RETINA. 169 
 
 has plugged the artery, the swelling of the retina 
 gradually disappears and with the disc undergoes 
 atrophy. The vessels of the retina diminish until 
 they appear like white threads. Cholesterin crys- 
 tals and pigmentation may make their appearance 
 principally about the disc and macula. As soon as 
 plugging of the central artery takes place, central 
 vision is promptly lost. If the eye happens to be 
 supplied with a cilio-retinal vessel (see Chapter IV. 
 and Plate I. ) then some central vision may be main- 
 tained, otherwise central vision would be cut off. 
 Embolism of a branch of the artery will cut off the 
 vision in the field corresponding to that portion of 
 the retina supplied by this branch, and vision may 
 remain quite good or normal at the macula. 
 
 Cause. This cannot be definitely determined. 
 The most common cause is some disease in or about 
 the heart. Valvular disease, vegetations, endocar- 
 ditis, aneurism of the aorta and carotid, changes in 
 the vessel walls (endarteritis and sclerosis), syph- 
 ilis, nephritis, pregnancy, etc. Usually one eye 
 alone is affected. 
 
 Diagnosis. Sudden stoppage of the blood 
 stream in the arteries, edema (opacity) in the 
 retina, cherry red spot in macula. 
 
 Sudden loss of vision, and without pain, although 
 there may have been some few premonitions, such 
 as slight dizziness, slight headache, and possibly 
 flashes of light. These same symptoms sometimes 
 precede detachment of the retina. 
 
170 THE OPHTHALMOSCOPE. 
 
 Prognosis. While this is most unfavorable, as 
 atrophy usually follows and blindness is the final 
 outcome, yet the presence of a cilio-retinal vessel 
 leaves some hope for what would otherwise be con- 
 sidered an almost hopeless condition. 
 
 Treatment. With an unfavorable prognosis, 
 treatment seems almost a waste of time and energy. 
 Yet treatment must not be withheld," as some good 
 may be accomplished and has been accomplished in 
 a few instances. If a history of syphilis is ob- 
 tained or suspected the case should be treated vigor- 
 ously along these lines, viz., mercurial inunctions, 
 pilocarpin sweats, and internally the iodid of pot- 
 ash should be pushed to the extreme point of toler- 
 ance. In fact, the iodid is indicated in nearly every 
 instance. The patient's heart should have careful 
 consideration and treatment if necessary. Digital 
 massage to the eye and nitrate of amyl and digitalis 
 internally are recommended. 
 
 Thrombosis of the Central Vein (Plate III.). 
 When this condition is complete the following 
 changes will be observed : 
 
 1. Changes in the Disc. The disc appears ele- 
 vated, hazy, or opaque and its margins indistinct 
 and striated, and late in the disease, may be hidden 
 from view. 
 
 2. Changes in Retina. The entire eye ground is 
 covered with many large hemorrhages, some pink 
 in color but most of them very dark red with flame- 
 shaped edges. The retina itself is foggy and 
 
PLATE III. 
 
 THROMBOSIS OF THE CENTRAL VEIN OF THE LEFT EYE. ALSO CALLED 
 APOPLEXY OF THE RETINA AND HEMORRHAGIC RETINITIS. 
 
 Mr. A. G. B. Aged 65 years. 
 
 History. Good health until two years before coming under obser- 
 vation. At that time developed a swelling in right side of the neck 
 which was removed at Presbyterian Hospital in Philadelphia and 
 microscopically diagnosed as epithelioma. A second operation at 
 the same hospital six months later for the same condition ; the 
 wound never healed and patient refused further surgical interfer- 
 ence. First noticed failing vision and everything appearing of a 
 red color five days before coming under observation. 
 
 Vision of right eye 20/20. Vision of left eye 1/120. 
 
 Fundus Changes. Fundus of right eye almost normal except for 
 one or two small flame-shaped hemorrhages in neighborhood of the 
 macula. 
 
 Left Eye. Acute papillitis. Disc very much swollen and apex 
 seen with + 4 D. and fundus without any lens at the sight hole. 
 Arteries small and very few of them in view. The veins are very 
 tortuous, looking like half hoops or serpentine, hence the condition 
 as described in the text of " Medusa Nerve." The light streak in 
 the veins is conspicuous at the top of each loop. The hemorrhages 
 are of all sizes and shapes and shades of red. 
 
 172 
 
PLATE III 
 
 Thrombosis of the Central Vein 
 (So- called Hemorrhagic Retinitis) 
 
THROMBOSIS OF CENTRAL VEIN. 175 
 
 sooner or later becomes of a yellowish-gray color. 
 
 3. Changes in Veins. The veins are full and 
 tortuous and have a blackish appearance and pulsa- 
 tion may be detected. The appearance of the veins 
 has been compared to the hair of Medusa. 
 
 4. Changes in Arteries. These are small ana 
 may be hidden or invisible. The vitreous usually 
 contains opacities. 
 
 If thrombosis affects a branch of the vein, then 
 the above conditions would be in keeping for the 
 corresponding portion of the retina. 
 
 Cause. Thrombosis usually occurs in elderly 
 people who suffer with atheroma or heart disease. 
 Phlegmons, abscesses, erysipelas and inflammatory 
 diseases of the orbit are a few of the causes of 
 venous thrombosis in the retina. Both eyes may be 
 affected, especially if erysipelas is the cause, though 
 usually one eye alone is affected. Prognosis is most 
 unfavorable, as blindness usually follows and pos- 
 sibly enucleation may be necessary (see Apoplexy 
 of the Retina). 
 
 Treatment. This is of very little avail and must 
 be directed to the underlying cause. 
 
 16 
 
CHAPTER VIII. 
 
 DISEASES OF THE RETINA. 
 
 Diseases of the Retina. These are many and 
 are named principally from the underlying cause, 
 but no matter what the cause may be, the ophthal- 
 moscope reveals one or more of the many changes 
 described on the following pages. 
 
 Inflammation of the Retina Without Regard 
 to its Variety. For very good reasons inflamma- 
 tion of the retina may be divided into two kinds, 
 superficial and deep, or inflammation of the inner 
 layers and inflammation of the outer or deeper 
 layers. When the inflammation affects the inner 
 layers the ophthalmoscopic picture is most conspic- 
 uous, and yet with all the conspicuous disturb- 
 ance in the retina central vision may not, for the time 
 being, be seriously damaged, whereas, when inflam- 
 mation affects the deeper layers there may not be 
 such apparent or prominent changes, and yet the 
 vision may be very much diminished. It is hardly 
 necessary to state that it is not always possible to 
 have an inflammation limited to the inner or deeper 
 layers by themselves, for the inflammation may pass 
 from one to the other in a very short time. Inflam- 
 mation of the retina may also extend to the underly- 
 ing choroid, producing retino-choroiditis, and vice 
 
 176 
 
DISTORTION OF OBJECTS. I 7 ^ 
 
 versa, inflammation of the choroid may extend to 
 the retina, producing chorio-retinitis, but a simple 
 inflammation of the retina, while it may not produce 
 a choroiditis at the same time, may, by virtue of the 
 retinitis, give the choroid an unnatural appearance, 
 as if it were rough or granular, spoken of as " gran- 
 ular changes in the choroid." 
 
 Change in Visual Acuity. This depends upon 
 the part of the retina affected and also upon the 
 extent of the inflammation. Central vision will 
 remain good if the center of the macula is not in- 
 volved or central vision diminishes in proportion to 
 the amount of involvement of the macula and fovea. 
 The chart for the field of vision will show contrac- 
 tion and occasionally scotomata. 
 
 Distortion of Objects. Objects may appear 
 smaller than normal (micropsia), or may appear 
 out of their normal shape or alinement (meta- 
 morphopsia), when the rods and cones have been 
 crowded together or separated or changed from 
 their normal level by inflammation, swelling or 
 exudates. 
 
 Diagnosis. A positive diagnosis of retinitis is 
 an opacity or loss of transparency of this mem- 
 brane ; the other conditions, i. e., hemorrhages, exu- 
 dates, pigmentation, etc., may add color to the 
 picture. 
 
 Prognosis. This depends on the cause, the part 
 of the retina involved, and the extent of the in- 
 flammation. The prognosis is most favorable when 
 
I 7 THE OPHTHALMOSCOPE. 
 
 the retinitis is due to syphilis and the inflammation 
 is not too extensive by the time the patient comes 
 under observation. When the retinitis is due to 
 Bright's disease or diabetes or brain tumor or men- 
 ingitis the prognosis is certainly grave. 
 
 Course and Complications. Retinitis may be 
 acute or chronic. It may be complicated with in- 
 flammation of the choroid (retino-choroiditis) 
 (Plate XI.) with inflammation of the papilla 
 (neuro-retinitis) (Plate IV.) ; with inflammation 
 of the iris and ciliary body. Eventually, after the 
 retinitis subsides, the retina may atrophy. The 
 central and peripheral vision in this disease is af- 
 fected according to the amount and part of the 
 retina involved. 
 
 Treatment of Retinitis in General. The treat- 
 ment of retinitis resolves itself into the treatment of 
 the underlying cause, and also in keeping the retina 
 at rest by the use of a cycloplegic and dark glasses ; 
 blood letting from the temples, the use of pilocarpin 
 sweats, and attention to the general condition. 
 
 Changes in the Retina indicative of disease are 
 the following: (i) opacities, (2) edema, (3) exu- 
 dations, (4) hemorrhages, (5) pigment changes, 
 (6) changes in the vascularity, (7) detachment, and 
 (8) atrophy. 
 
 Opacities. The one condition of the retina per se 
 which is distinctively pathologic is its loss of trans- 
 parency commonly spoken of as opacity. A similar 
 condition or loss of transparency, also spoken of as 
 
OPACITIES. I 79 
 
 opacity, occurs in the cornea, lens and vitreous and 
 is an early manifestation of alteration in any one 
 of these structures. As already stated the retinal 
 fibers lying in front of the pigment layer are trans- 
 parent in health, and it is this quality of losing this 
 transparency as an early manifestation of disease 
 or injury that gives the observer the opportunity to 
 make an early diagnosis of retinitis. The beginner 
 in ophthalmoscopy should make a permanent mental 
 impression of this and other facts, to be mentioned 
 later, so that he will not make a hasty diagnosis of 
 retinitis simply because the eye ground looks unusu- 
 ally red. An opacity of the retina may be very 
 slight or faint, resembling a slight fog or mist (Plate 
 II. ), or the opacity may be very dense, resembling a 
 white cloud (Plate IV.), or the density of the opacity 
 may be intermediate between these two extremes 
 ( Plate V. ) . With the direct method of examination 
 there is no glass in the ophthalmoscope which will 
 give a clear cut picture of the fundus at the place of 
 the opacity. Opacities may be small or large, just 
 one, or a few, or a great many ; they may be scattered 
 throughout the retina, or they may be quite uniform 
 and occupy most of the retina or only a small portion 
 of it. It must also be borne in mind that the retina 
 is thick at the disc and thin at the macula, and there- 
 fore the want of transparency becomes most con- 
 spicuous at the disc when this is the portion in- 
 volved, whereas an opacity at the macula, which 
 is the thinnest part of the retina, does not hide or 
 
l8o THE OPHTHALMOSCOPE. 
 
 veil the underlying structures to the same extent 
 that it would otherwise, and hence the macula may 
 show as a crimson spot during a certain stage of 
 retinitis (see Embolism of Central Artery, and 
 Plate II.). It has already been stated that the 
 cornea, lens and vitreous will also show opacity as 
 a pathologic characteristic, and therefore if an 
 opacity in one or all of these structures is present 
 care must be taken to differentiate them as follows : 
 Opacities of the cornea and lens are to be studied 
 with oblique light (Figs. 16, 17 and 18). Diffuse 
 cloudiness of the vitreous is to be examined with 
 the ophthalmoscope and is seen to be the same, no 
 matter in which direction the eye is turned, and 
 the blurred retinal vessels on the disc and in the 
 fundus appear equally obscure through the foggy 
 or opaque vitreous. If the vitreous cloud lies well 
 forward in the vitreous, just back of the lens, then 
 it may be seen with the oblique light and condensing 
 lens. 
 
 In opacity of the retina, however, some vessels 
 may be focused clearly while others may be obscure ; 
 these latter being obscured by the retinal opacity 
 (Plate IV.). The periphery of the retina is most 
 clearly seen as a rule, as it is usually free from 
 opacities. It is well to remember that it is not 
 impossible to have opacities of the cornea, lens, vit- 
 reous and retina in one eye at one and the same time. 
 
 Edema. Edema of the retina may be described 
 as a progressive or advanced opacity of this struc- 
 
EXUDATION. l8l 
 
 ture, and, like opacity, may be limited to a certain 
 portion or may be diffuse throughout the retina. 
 As edema means swelling, the retinal vessels may 
 be seen passing over or through the edematous 
 area with resulting changes in their appearance, 
 viz., they lose their light streak, appear dark and 
 the arteries and veins, while in the swollen portion 
 of the retina, cannot always be distinguished from 
 each other (Plate V.). 
 
 Exudation. This is an inflammatory product, 
 or it may be metastatic, usually circumscribed and 
 may appear as small dots (Plate V.), or as large 
 masses covering extensive areas (Plate IV.). The 
 blood vessels that pass through or over these exu- 
 dations, give an exaggerated picture of the condi- 
 tion as seen in edema. The periphery of the eye 
 ground is not usually involved to the same extent 
 as the neighborhood of the disc (Plate IV.). Ex- 
 udates are often spoken of as serous, albuminous 
 and purulent. The serous are more or less grayish 
 in color, or even white (Plate IV.), and may con- 
 tain lymph corpuscles. The albuminous are yellow 
 or yellowish-white in color (Plate V.), and later 
 may contain connective tissue. The purulent exu- 
 date usually involves the vitreous to such an extent 
 that unless seen very early no view of the retina 
 can be made out, the vitreous seeming to be filled 
 with a large yellowish mass. Seen early, small 
 round yellow dots would be recognized in and about 
 the disc and macula. 
 
1 82 THE OPHTHALMOSCOPE. 
 
 For a description of hemorrhages, pigment 
 changes and changes in vascularity, see Chapter 
 VII. 
 
 Diffuse Retinitis; Serous Retinitis; Edema of 
 the Retina; Retinitis Simplex. This may be en- 
 tirely local or a local manifestation of a constitu- 
 tional disease. As the name (diffuse) implies, the 
 inflammation is usually quite extensive and occupies 
 a considerable portion of the retina; or it may in- 
 volve only a small part or parts of the retina ( Plate 
 V.). One or both eyes may be affected. The in- 
 flammation may affect the inner or the outer layers, 
 but the inner layers are usually the ones affected. 
 The ophthalmoscope reveals a grayish color of the 
 retina; this may be very faint, like a gauzy veil, 
 or dense like a heavy fog, and this latter obscures 
 the retinal vessels. The chief characteristic of this 
 disease is the infiltration which causes the edema 
 and opacity of the retina. The arteries appear 
 straight and without any increase in size, possibly 
 they may be smaller than normal, whereas the 
 veins are increased in size and tortuous, and in 
 severe cases have an antero-posterior curve (Plate 
 V.). Diffuse retinitis accompanies choked disc, or 
 any inflammation of the disc may show some fog- 
 ging of the retina in its neighborhood or extending 
 out from the disc in the course of some one or more 
 of the larger vessels (Plates III., V.). Hemor- 
 rhages are not as common in diffuse retinitis as in 
 other varieties of inflammation of this structure. 
 
DIFFUSE RETINITIS OF RETINA. 183 
 
 When hemorrhages are seen in diffuse retinitis 
 they are usually small and striated and are usually 
 seen in the course of the vessels. The white areas 
 and the macular star-shaped figure are not often 
 seen in diffuse retinitis; they are to be found in 
 the albuminuric retinitis, but if they do occur in the 
 diffuse retinitis they signify that the outer layers 
 of the retina are involved. Naturally, too, if the 
 inner layers of the retina are seriously involved 
 the vitreous soon becomes implicated and diffuse 
 opacities of this structure are seen, and they in 
 turn increase the obscurity of the retinal picture. 
 
 Diffuse Retinitis of the Outer Layers of the 
 Retina. The inflammation of these layers lies 
 posterior to the vessels which may be plainly seen. 
 The hemorrhages are more or less rounded and not 
 flame-shaped. The exudate is inclined to be yellow- 
 ish and not gray. If the pigment layer is involved, 
 then when the inflammation begins to subside the 
 granules of pigment may be seen collected in irregu- 
 lar spots. If the inflammation extends deeper the 
 choroid becomes involved and the condition is one 
 of retino-choroiditis. 
 
 Cause. Exposure to bright light (snow blind- 
 ness), electric light, lightning, taking cold, sudden 
 stoppage of perspiration after violent exercise; 
 syphilis, congenital or acquired. In some instances 
 it is impossible to find a cause. 
 
 Treatment. Rest of the retina with cycloplegic 
 and dark glasses, and treatment of the cause. 
 
184 THE OPHTHALMOSCOPE. 
 
 Prognosis. This depends upon the cause. If 
 from syphilis the retinitis may clear up in a few 
 weeks under energetic specific treatment. When due 
 to other causes the prognosis is not quite so favor- 
 able. If the diffuse retinitis is of long standing it 
 may eventuate in atrophy of the retina with marked 
 failure, in vision; this latter is especially true if 
 the deep layers are involved. In other cases there 
 may be a formation of new vessels which are pro- 
 jected into the vitreous. 
 
 Circumscribed Retinitis. This is an inflamma- 
 tion of the retina which is limited in its extent, hence 
 called " circumscribed." It is often seen to follow 
 the course of the large vessels (Plate V.). Circum- 
 scribed retinitis at the macula, if in the deep layers 
 and affecting the pigment layer, seriously impairs 
 central vision and may destroy it. A consideration 
 of circumscribed retinitis is but a consideration of 
 the diffuse variety of retinitis, but limited in its 
 extent. Virtually diffuse and circumscribed retin- 
 itis are therefore one and the same disease. The 
 causes of each, however, are not always the same. 
 
 Retinitis Punctata. Some authorities object to 
 this name, as the ophthalmoscope does not reveal 
 any decided inflammation, and the same may be said 
 about retinitis pigmentosa; however, these diseases 
 do have a low grade of inflammation as revealed 
 by the microscope. As its name implies (retinitis 
 punctata), the ophthalmoscope reveals many minute 
 white or yellowish-colored dots, and these are best 
 
RETINITIS PUNCTATA. 185 
 
 seen with the direct method, and as they are very 
 closely packed together they give a stippled appear- 
 ance to that portion of the retina where found, 
 and this is usually between the macula .and the 
 disc. The spots are not always in this location, but 
 may be scattered over the fundus, and while they 
 are usually round in shape they may occasionally 
 appear oval. 
 
 These punctate changes have been variously de- 
 scribed or classified and named by different ob- 
 servers and referred to as " dots " as follows : 
 
 Nettleship's Dots. These dots are quite small 
 and numerous, dead white in color, not glistening; 
 they occupy the space between macula and periph- 
 ery, and have been seen scattered over the fundus. 
 
 Gunn's Dots (also called " Crick's " Dots). 
 These dots are quite small and few in number, yel- 
 lowish in color and occupy the macular region. A 
 rare condition, and found usually in young subjects. 
 
 Retinitis punctata albescens of Mooren resembles 
 Nettleship's dots and gives night blindness as a 
 symptom. The ophthalmoscope reveals the fundus 
 having many or a few white dots which are small 
 and round in form. 
 
 Punctate retinitis is found in the eyes of old 
 people who have atheromatous vessels, whereas 
 Gunn's dots are found in the eyes of young patients. 
 
 Prognosis. Not unfavorable as vision is not 
 usually impaired, except possibly for some slight 
 
I 86 THE OPHTHALMOSCOPE. 
 
 contraction in the field or for a moderate amount 
 of night blindness. 
 
 Treatment. Xot benefited by any treatment 
 though electricity, alteratives, etc., have been tried 
 and recommended. 
 
 Apoplexy of Retina (see Plate III.). The dis- 
 ease under consideration partakes of the nature of 
 a disease of the walls of the vessels and this so 
 weakens them that the blood corpuscles make their 
 escape into the retina, a condition primarily of vas- 
 culitis. Retinitis may now develop from the 
 presence of the blood, the blood being the exciting 
 cause of the retinitis. If the hemorrhage is a large 
 one, or many smaller hemorrhages coalesce, the 
 intra-ocular pressure may become so increased as 
 to develop acute glaucoma (hemorrhagic glau- 
 coma). In apoplexy of the retina the arteries are 
 smaller than normal. This condition of the arteries 
 might lead one to suppose, that the hemorrhage 
 was from a break in the vessel, but this must be a 
 mistake as specimens examined fail to reveal any 
 ruptures. Hemorrhages are usually from the large 
 vessels, therefore they are seen in the neighbor- 
 hood of the disc or possibly on the disc itself; these 
 hemorrhages may be few or many, they may vary 
 in size and shape, though they are usually quite 
 large as compared to hemorrhages occurring in 
 other varieties of retinitis (see Plate VI.). Apo- 
 plexy of the retina is usually a condition of the 
 aged and often accompanies changes in the circula- 
 
IIEMORRHAGIC RETINITIS. 187 
 
 tion and heart, and it may be a prodrome of cerebral 
 apoplexy. 
 
 Causes. Usually diseases of heart and blood 
 vessels, with the underlying cause for the change in 
 the blood and vessel walls, arterio-sclerosis, etc. 
 
 Prognosis. Very unfavorable. 
 
 Treatment. Rest and treatment of underlying 
 cause. 
 
 Hemorrhagic Retinitis. Hemorrhages in the 
 retina without inflammation of the retina may be 
 called apoplexy of the retina. The true name for 
 hemorrhagic retinitis is therefore an inflammation 
 of the retina with accompanying hemorrhages. 
 Apoplexy of the retina, or a hemorrhage in the 
 retina will produce an inflammation of the retina 
 and hence is called hemorrhagic retinitis. Apoplexy 
 of the retina usually eventuates into hemorrhagic 
 retinitis. The ophthalmoscope reveals a cloudy 
 retina with swollen disc which has its edges ob- 
 scured. The arteries are small and veins large and 
 tortuous. The hemorrhages are many and varied ; 
 round, flame-shaped, linear and irregular and ap- 
 pear throughout the eye ground. 
 
 Causes. Disease of heart and blood vessels; 
 abnormal suppression of menses ; syphilis, etc. 
 
 Prognosis. This is usually quite grave as the 
 underlying cause may be a structural change in 
 the walls of the vessels or the heart may be seri- 
 ously involved. Vision is liable to serious and per- 
 manent injury from the same cause. When caused 
 by syphilis the prognosis is rather more favorable. 
 
I 88 THE OPHTHALMOSCOPE. 
 
 Treatment. Rest of the eye or eyes, as the dis- 
 ease may be monocular; with appropriate treat- 
 ment for the underlying cause. 
 
 Syphilitic Retinitis. While syphilis is one of 
 the most common causes of retinitis it is interesting 
 to note the fact, that there is no one variety of 
 retinitis that is typically syphilitic. The nearest 
 approach to this is the diffuse variety, but it only 
 proves that syphilis may be manifest in the retina 
 by affecting the superficial or deep layers or it may 
 be circumscribed, or the retinitis may be accom- 
 panied by choroiditis (syphilitic retino-choroiditis) 
 (Plate XL), or the vitreous, ciliary body and iris 
 may also be affected at one and the same time, or 
 singly. Hemorrhages are not usually the conspicu- 
 ous factors in syphilitic retinitis as in some varieties 
 of retinitis, though they do occur at times and are 
 often quite large. The vision is often markedly 
 affected or impaired, depending of course upon the 
 stage of the disease, its variety and the part of the 
 eye ground involved. 
 
 Course and Treatment. This disease is usually 
 chronic. The treatment of course is anti-syphilitic. 
 Mercurial inunctions, iodids internally and the use 
 of pilocarpin sweats. The prognosis depends on 
 the stage of the inflammation, the part of the retina 
 involved and the persistence and vigor with which 
 the treatment is carried out and maintained. 
 
 Splenic or Leukemic Retinitis, Retinitis from 
 Anemia. The early ophthalmoscopic changes of 
 this disease are not unlike those of diffuse retinitis, 
 
PLATE IV. 
 
 ALBUMINURIC RETINITIS. RETINITIS OF BRIGHT'S DISEASE. BRIGHT'S 
 RETINA. FUNDUS OF RIGHT EYE. DIRECT METHOD. 
 
 Miss K. C. Aged 49 years. 
 
 History. First noticed foggy vision in April, 1904, and came for 
 examination October 8 of same year, stating that when left eye was 
 closed objects seen with right eye were quite indistinct on their 
 left side (positive scotoma). 
 
 Vision of right eye with + -5 D- C + i-SO Cyl. axis 180 de- 
 grees = IV/XX. 
 
 Vision of left eye with + 0.50 D. C + J -5o Cyl. axis 180 de- 
 grees = IV/VIISS. 
 
 Fundus Changes. Fundus of each eye very similar, but that of 
 the right typically marked. Swollen disc, striated edges; exuda- 
 tions (" snow banks ") about its edges with two areas above and 
 one below the disc. Macular figure unusually well marked. Many 
 scattered and flame-shaped hemorrhages seen in the periphery and 
 about the disc. Vessels about the disc show effusion into their 
 sheaths by the white edge at each side of the vessel. The disc 
 resembles that of choked disc in brain tumor, but the " snow banks " 
 and macular figure are almost too conspicuous for such a diagnosis. 
 The history of the patient, not having any headache, nausea or 
 vomiting, no double vision or any indication of extra-ocular palsies, 
 excluded the idea of brain tumor. The urine analysis confirmed 
 the kidney changes (interstitial nephritis). 
 
 Decapsulation of each kidney was performed February 25, 1905, 
 and patient died fourteen days later of uremic coma. 
 
 190 
 
PLATE IV 
 
 Rlbuminuric Kstinitis 
 
SPLENIC RETINITIS. 193 
 
 but later on the fundus may, and often does, appear 
 of a light orange color, which authorities recognize 
 as quite characteristic of this variety of retinitis, 
 and yet there are cases of splenic retinitis which do 
 not have this characteristic feature. The veins fre- 
 quently have an unusual tortuosity and are quite 
 distended and of a rose red color. The arteries ap- 
 pear normal and of an orange yellow color. The 
 disc may appear normal or it may be prominent, and 
 if prominent its edges are hazy. Hemorrhages 
 both large and small are seen in any part of the 
 fundus, but usually about the equator ; they are cir- 
 cular in form. Hemorrhages may also be seen in 
 the macular region and about the disc. As the old 
 hemorrhages disappear new ones are seen to make 
 their appearance. The hemorrhages surround ele- 
 vated white spots which vary in size and are com- 
 posed of lymph corpuscles. 
 
 Treatment. This applies to the cause. 
 
 Renal Retinitis, Retinitis of Bright's Disease, 
 Retinitis Nephritica, Albuminuric Retinitis, 
 Papillo-retinitis (Plate IV.). This may occur in 
 any variety of disease of the kidneys, especially in 
 the chronic form, most frequently with contracted 
 kidney, also with the large white kidney. The 
 most common variety of retinitis is the neuro-retin- 
 itis (papillo-retinitis). The ophthalmoscope reveals 
 the following characteristics: (a) The disc is 
 swollen and hyperemic or actively inflamed; (b) 
 large, round, white or yellowish-white massings ar- 
 '7 
 
194 THE OPHTHALMOSCOPE. 
 
 ranged in circular form are seen to partly or com- 
 pletely surround the disc; this is quite distinctive of 
 albuminuric retinitis, whereas in other varieties 
 of retinitis the exudate is not so rounded but elon- 
 gated and follows the course of the large vessels. 
 The massings around the disc have been called 
 " snow bank," and the name is obvious, (c) White 
 spots, small in size, seen at the macula (due to fatty 
 degeneration of exudates and retinal elements) 
 form a characteristic picture of Bright's disease. 
 These white dots appear early in the disease and 
 later on they enlarge or coalesce into radiations like 
 the spokes of a wheel, with the macula as a center, 
 their radiations resemble the points of a star 
 and the figure has been called " stellar " or " macu- 
 lar figure " ; this figure is not always complete. 
 However, whether complete or partial, it is con- 
 sidered quite pathognomonic of Bright's disease 
 until other factors can be brought out to disprove 
 this diagnosis. Therefore, the macular white dots 
 are sometimes seen in other varieties of inflamma- 
 tion of the retina, (d) Many of the retinal vessels 
 will be seen to pass over or are hidden in the white 
 patches. The arteries appear normal or smaller 
 in size, and the veins are distended, slightly tortuous 
 and dark in color. Arteries and veins may show 
 a white streak at their borders, (e) Hemorrhages 
 may occur at any time during the progress of the 
 disease; they are usually in the nerve fiber layer 
 and therefore flame-shaped. Small hemorrhages 
 
DIAGNOSIS OF RENAL RETINITIS. 1 95 
 
 in the deep layers (round-shaped hemorrhages), as 
 an early manifestation, foretell a most unfavorable 
 prognosis. 
 
 Differential Diagnosis. Retinitis of Bright's 
 disease may be mistaken for retinitis accompanying 
 brain tumor, and this differentiation is not always 
 easy or positive from the eye condition alone ; how- 
 ever, the following may assist materially in the 
 decision. 
 
 Bright's Disease. Brain Tumor. 
 
 Disc usually has uniform or dif- Disc very much elevated and 
 
 fuse redness and occasionally vessels seen passing down into 
 
 a slight swelling, and vessels level of retina (Plate III.). 
 
 buried in the swelling which 
 
 is not as prominent as in 
 
 choked disc. 
 
 Large vessels show very little Veins very large, full and tortu- 
 
 change, the veins may be ous very early in the disease. 
 
 slightly tortuous and darker in 
 ' color. 
 
 Retinal changes appear early. Retinal changes come late. 
 
 White exudates are numerous White exudates not so early. 
 
 and coalesce ; seen around disc Macular star may not be 
 
 and at the macular region. present. 
 
 Albuminuric retinitis rarely affects one eye 
 alone ; both eyes are usually affected, but one may 
 be affected before its fellow. 
 
 The above description is that of a typical case 
 of albuminuric retinitis, but there are many de- 
 partures from this complete picture; in fact, the 
 complete picture is not the common one. There are 
 four other principal pictures of albuminuric retin- 
 itis, described and named from a chief feature seen 
 in the fundus. 
 
196 THE OPHTHALMOSCOPE. 
 
 1. Degenerative Albuminuric Retinitis. In 
 this picture the whitish ring about the disc is ab- 
 sent and the stellate figure about the macula is not 
 complete. The disc is red and swollen but not 
 highly inflamed; its edges are hazy. The hemor- 
 rhages are nearly, if not all, flame-shaped, occupy- 
 ing the nerve fiber layer. 
 
 2. Hemorrhagic Retinitis of Bright's Disease. 
 As its name implies, this variety is characterized 
 by many hemorrhages scattered over the fundus, 
 and they appear as an early manifestation before 
 the disc becomes involved. When the hemor- 
 rhages are absorbed white areas take their places, 
 and if the underlying choroid has been involved, 
 these areas may be partially pigmented. 
 
 3. Albuminuric Neuro-retinitis (Plate V.). 
 Here the picture is one of high grade inflamma- 
 tion of the disc and retina with hemorrhages and 
 exudates as a consequence of such inflammation. 
 
 4. Albuminuric Papillitis. The chief charac- 
 teristic feature here is the inflammation of the disc, 
 giving the typical "choked disc" (papillitis). 
 
 Albuminuric retinitis occurring during preg- 
 nancy is the neuro-retinitis just described. The 
 white areas are large and scattered and due to 
 serous effusion ; the hemorrhages are also scattered. 
 The white areas do not usually have the same radi- 
 ating figure in the macula as in the typical picture 
 described and shown in Plate IV. 
 
 Prognosis for Vision. Vision is usually ma- 
 
PLATE V 
 
 lilbuminuric Retinitis of Pregnancy 
 
PLATE V. 
 
 ALBUMINURIC RETINITIS OF PREGNANCY. NEURO-RETINITIS. 
 
 PAPILLO-RETINITIS. FUNDUS OF LEFT EYE. 
 
 DIRECT METHOD. 
 
 Mrs. O. Aged 28 years. 
 
 Fundus Changes. Each fundus of this patient showed neuro- 
 retinitis, but much more marked in the left, although the right eye 
 had its vision destroyed by a large hemorrhage into the macula. 
 
 Vision of right eye with + i D. C + I-5O Cyl. axis 100 degrees = 
 light perception. 
 
 Vision of left eye with -f- 1.50 D. C + 2.50 Cyl. axis 90 degrees = 
 V/XIK?). 
 
 The disc is hidden and slightly swollen, but not to the same ex- 
 tent as in Plate IV. The punctate dots above and at the macula 
 (neuritic dots) are quite conspicuous. Areas of exudation are 
 some distance from the disc. The hemorrhages are numerous, small 
 and flame-shaped. The veins are full and tortuous and some of 
 them are covered by the swollen retina. Patient recovered her 
 health, but with damaged vision, as above recorded, with her cor- 
 recting glasses. The following letter from Dr. Davis is self-ex- 
 planatory and gives the patient's history : 
 
 April 14, 1905. 
 DR. JAMES THORINGTON, 
 
 120 South :8th Street, Phila. 
 
 My Dear Dr. Thorington: Regarding our patient, Mrs. O. at 
 the Polyclinic, the salient points of the history are as follows : 
 
 Patient, aged 28; multipara; family history, negative; has had 
 scarlet fever and diphtheria. No complications in previous preg- 
 nancies or labors ; has had chlorosis ; and has had frequent head- 
 aches at menstruation ; has worn glasses. 
 
 During pregnancy which has just terminated, felt languid, had 
 occasional nose-bleed and slight vaginal hemorrhage. She received 
 no competent medical care. Her urine was not examined. On the 
 evening preceding admission to Polyclinic Hospital she felt badly 
 and was nauseated. Convulsions began in the early morning. She 
 had eight before admission. Temperature on admission was 102. 
 A convulsion occurred immediately after admission. She was 
 treated by venesection with intravenous transfusion of salt solution, 
 hot packs with copious enteroclysis. Labor gradually came on, and 
 when the cervix had softened and partly dilated, the patient by 
 podalic version was delivered of a dead 7-months child, 35 centi- 
 metres long. She had no convulsion after delivery, and slowly 
 regained consciousness. 
 
 I 9 7 
 
The placenta was not examined, nor- was the fetus submitted to 
 examination. 
 
 Examination of the patient's urine, with the clinical history of 
 her case, shows that her eclampsia was the result of toxemia of 
 nephritic origin. That this had proceeded sufficiently far to pro- 
 duce disintegration of the red blood corpuscles was shown by the 
 fact that the patient had nasal and vaginal hemorrhage before labor, 
 and also from the occurrence of retinal hemorrhages, as reported 
 by you. 
 
 So far as prognosis for life is concerned, these cases are more 
 favorable than toxemia of nephritic origin. 
 
 This patient will gradually recover her usual general health, and 
 can avoid a subsequent toxemia, should pregnancy again occur. 
 
 In other cases which I have seen, the eye condition has gradually 
 improved, and patients who were practically blind, before delivery, 
 have obtained fair vision. 
 
 The treatment employed in this case was that which I usually 
 employ with these patients ; namely, the abstraction of a small quan- 
 tity of blood, followed by intravenous saline transfusion to neutral- 
 ize poisons circulating in the blood serum, copious lavage of the 
 stomach and intestines, with perspiration as free as possible. When 
 labor begins, it is aided and not allowed to continue long. Hoping 
 that these notes will be what you desire, I remain, 
 
 Very truly yours, 
 
 EDW. P. DAVIS. 
 
 198 
 
PLATE VI. 
 RETINITIS DIABETICA. FUNDUS OF RIGHT EYE. DIRECT METHOD. 
 
 Mr. C. B. E. Aged 64 years. 
 
 History. Suffering from diabetes for three years and sight of 
 each eye has been failing gradually for the past three months, but 
 within the last few days has not been able to read with any glasses 
 he could purchase. Now his vision is so defective he has difficulty 
 in getting around the city and is afraid of getting run over. 
 
 Fundus Changes. Arteriosclerosis showing in the upper and 
 lower temporal vessels where they cross. Small flame-shaped and 
 round hemorrhages scattered irregularly in the fundus. The disc 
 edges are foggy and the membrana cribrosa is indistinct. The inter- 
 mediate zone and in fact the entire disc has a canary yellow color 
 appearance. Fundus of the left eye is practically the same as the 
 right. 
 
 Vision of right eye with -j- i D. C + ! Cyl. axis 180 degrees = 
 VI/XL. 
 
 Vision of the left eye with same correction is the same as the 
 right. 
 
 Cannot read newspaper print with any additional glass. 
 
 202 
 
PLATE VI 
 
 Retinitis Diabetica 
 
PROGNOSIS FOR PATIENTS LIFE. 205 
 
 terially damaged and may be destroyed as the vital 
 part of the eye (the macula) is seriously involved, 
 as a rule. The failing vision may be the very first 
 symptom which brings the patient's attention to his 
 eyes, and hence to his kidney condition. 
 
 Prognosis for Patient's Life. Most patients 
 with albuminuric retinitis (except when due to 
 pregnancy) die within two years (fourteen months 
 has been given as the average) from the time the 
 retinas are primarily involved. There are excep- 
 tions to this statement. The writer has the personal 
 knowledge and has examined the eyes of a col- 
 league's patient, who has had albuminuric retinitis 
 for over ten years, and who was told nine years ago 
 that he would not live another year. The writer has 
 under observation two cases of albuminuric retinitis 
 that have existed for over two years, and both pa- 
 tients are in fairly good health ; both these patients 
 are syphilitic and have been, and are irregularly un- 
 der specific treatment. It is the writer's belief and 
 experience that syphilitic patients, with albuminuric 
 retinitis, coming under active specific treatment give 
 a much more favorable prognosis for a longer life 
 than a patient ivho develops Bright's retinitis with- 
 out this specific (cause?) history. 
 
 Treatment. This applies directly to the kidneys 
 and the underlying cause. As far as the eyes are 
 concerned, they should be placed at rest with dark 
 glasses and the use of a cycloplegic, and all use of 
 the eyes at any near work must be stopped. 
 18 
 
206 THE OPHTHALMOSCOPE. 
 
 Diabetic Retinitis (Plate VI.). Involvement of 
 the retina is not a common condition in diabetes, 
 it is usually a late manifestation, but when it 
 does occur it is quite serious. Diabetes does, 
 however, produce quite marked and rapid changes 
 in the refraction by its action on the lens, and 
 so-called diabetic cataract may be a result. The 
 snow bank about the disc and the macular star are 
 usually absent in diabetes. The hemorrhages are 
 common, flame-shaped and round and usually large. 
 The disc is not markedly swollen ; late in the disease 
 it may appear of a pale yellow color. However, 
 there are instances when diabetic retinitis simulates 
 the albuminuric variety so closely that the presence 
 of sugar or albumen in the urine must settle the 
 diagnosis, or possibly both conditions (albuminuria 
 and diabetes) may exist in the same subject. Hem- 
 orrhagic retinitis may occur during diabetic retin- 
 itis. Choked disc may be present in diabetes, and 
 also with brain tumor. While Bright's disease and 
 also diabetes usually affect both eyes respectively 
 at the same time, yet either may occur in one eye 
 several weeks or months before the other eye is 
 affected. 
 
 Course and Complications. Cataract, inflam- 
 mation of the iris and vitreous opacities, are added 
 complications to the failing central and peripheral 
 vision. 
 
 Prognosis. Unfavorable, depending of course 
 upon the condition of the disc and the retinal in- 
 volvement and complications. 
 
PLATE VII. 
 RETINITIS PIGMENTOSA. FUNDUS OF RIGHT EYE. DIRECT METHOD. 
 
 Mr. S. J. B. Aged 53 years. Cigarmaker. Englishman by birth. 
 
 Vision of right eye IV/XX with 2.50 D. C + 2 -75 Cyl. axis 
 i8o=IV/X. 
 
 Vision of left eye IV/XX with 2.00 D. C + 2.50 Cyl. axis 12 
 degrees = IV/X. 
 
 History. So far as patient knows has always had day sight 
 (hemeralopia), but could not see at night without a very bright 
 light, and has therefore remained in doors at night unless he had 
 company after leaving the house in the evening. Is in the habit 
 of hurrying home at twilight and dreads very dark or rainy days. 
 Knows that he had night blindness when he came to America in 
 1863, when about ten years of age. His condition has geen gradu- 
 ally getting worse. Has tried all kinds of glasses, but without much 
 assistance. This is proven by the above formulas. Parents are not 
 related and no one else in his family, so far as he knows, has ever 
 been similarly afflicted. Is a single man. Never had syphilis. Has 
 never married, as he was medically advised not to, as his eye con- 
 dition would very likely be inherited. 
 
 Fundus Changes. The periphery of the eye ground is character- 
 istic of many myopic eyes, the choroidal vessels being very conspic- 
 uous. The retinal vessels are not very numerous and the smaller 
 ones can be traced with difficulty in the periphery. The disc is 
 quite yellow in color. The retinal vessels are narrow. The lower 
 vein appears large at first, but this is due to the peculiar way in 
 which the pigment is deposited on its walls. The reflex immedi- 
 ately around the disc approximates the normal, but beyond this the 
 condition is atrophic. A few stellate pigment spots, together with 
 irregular pigment massings on the vessels, are scattered throughout 
 the fundus. This is an unusual variety of the disease under con- 
 sideration. The patient is color blind for red. See chart, Fig. 71. 
 
 208 
 
PLATE VII 
 
 Retinitis Pigmentasa 
 
RETINITIS PIGMENTOSA. 211 
 
 Treatment. That for diabetes. 
 Retinitis Pigmentosa (Plate VII.), Pigmen- 
 tary Degeneration of the Retina, Night-blindness 
 
 (Hemeralopia, yp-epa, day, and aty, sight). This 
 disease always affects both eyes (unless syphilitic), 
 it begins in childhood and gradually develops as 
 the patient grows older and if the patient lives to 
 be sixty years or more, then blindness will very 
 likely be the ultimate condition. The cause of this 
 peculiar disease is unknown, though statistics re- 
 veal the fact that about one case in three can be 
 traced to consanguinity of the parents. Syphilis, 
 congenital or acquired, is also a cause. 
 
 Pathology. The connective tissue of the entire 
 retina becomes thickened or hypertrophied and the 
 nerve elements atrophic (degenerated), this latter 
 gradually reducing visual acuity. The caliber of 
 the retinal vessels becomes narrowed by direct thick- 
 ening of their walls and the diameter of the ves- 
 sels gradually diminishes also. The retinal pig- 
 mentation becomes disturbed, and in a most 
 peculiar manner and one that has never been 
 satisfactorily explained. 
 
 Ophthalmoscopic Findings. The pigmentation 
 appears in masses or patches and is deposited in the 
 retina and it not only follows the course of the 
 retinal vessels but forms on the vessel walls; this 
 is quite a diagnostic feature of the disease. In 
 childhood or in the early stages of the disease this 
 pigmentation is seen only in the periphery of the 
 
212 
 
 THE OPHTHALMOSCOPE. 
 
 eye ground but later on these spots increase in 
 numbers and unite, sending off filiform processes, 
 so that they resemble bone corpuscles, and are often 
 star-shaped, and there may be other pigment mass- 
 ings present which are most irregular and may have 
 a spider-shaped formation, so that the retina in 
 some instances looks as if it had a black network 
 or irregularly folded veil stretched over it. This 
 
 FIG. 71. Form Field, showing contraction in all meridians. This is 
 the chart of the right eye of the patient with Retinitis Pigmentosa, as 
 illustrated in Plate VII. The outer edge of the black area represents the 
 normal field and the inner edge of the black area shows the contraction. 
 
 whole process of pigmentation begins well forward 
 and gradually extends inward toward the disc 
 in a uniform manner. When seen in childhood 
 this process of pigmentation is not well developed 
 but progresses slowly as the patient grows, unless 
 some intercurrent disease develops when the pig- 
 
RETINITIS PIGMENTOSA. 213 
 
 mentation may be hastened. One case under the 
 writer's observation (the parents of the patient were 
 second cousins) developed dorsal curvature of the 
 spine and the retinal disease increased rapidly. The 
 disc gradually loses its normal appearance and 
 takes on a yellowish-gray color and may eventually 
 become white, atrophic. Cases of retinitis pigmen- 
 tosa are often complicated with posterior polar 
 cataract and nystagmus, especially when congenital. 
 See description for Plate VII. 
 
 Subjective Symptoms. The chief characteris- 
 tic symptom, and the one by which the patient's 
 attention is first called to his condition, is the in- 
 ability to see distinctly when twilight begins or 
 after the sun goes down. He may see perfectly 
 well in day time so far as he knows, but after dark 
 he will stumble and bump into objects. 
 
 Field of Vision. The field of vision becomes 
 more and more contracted as the disease progresses 
 and atrophy develops (Fig. 71). 
 
 Central Vision. This remains good much longer 
 than peripheral vision, but the condition means ulti- 
 mate blindness if the patient survives. The re- 
 fractive error is not known to influence the suscepti- 
 bility of an eye to the disease under consideration. 
 Many illustrated cases would indicate that the eyes 
 were hypermetropic and yet the fundus shown in 
 Plate VII. happened to be in a stretching myopic 
 eye that had the choroidal circulation very much 
 exposed in the periphery. 
 
214 THE OPHTHALMOSCOPE. 
 
 Differential Diagnosis. Retinitis pigmentosa is 
 not a common disease and ordinarily it is easily 
 differentiated from choroiditis or retino-choroiditis 
 which it is said to somewhat resemble. 
 
 Retinitis Pigmentosa Retino-choroiditis 
 
 (Plate VII.). (Plate XL). 
 
 Choroidal changes often absent. Choroidal changes present. 
 
 Pigment spots not round, but Pigment spots are round or in 
 
 stellate. form of rings or irregular 
 
 shapes. 
 
 Pigment follows course of ves- Pigment does not follow course 
 
 sels and often seen on top of of vessels to any great extent, 
 vessels. 
 
 Treatment of Retinitis Pigmentosa. If due 
 
 to syphilis, iodids and mercury should be ordered. 
 For the congenital variety strychnia and galvanism 
 should be tried, though the prognosis in such cases 
 is very grave. 
 
 Sclerosis of the Retina. Called also non-pig- 
 mented sclerosis. This is another variety of retin- 
 itis which gives a contracted field and blindness at 
 night ; the same symptoms are obtained as in retinitis 
 pigmentosa, therefore these two diseases markedly 
 resemble each other, but the ophthalmoscope does 
 not reveal the typical pigmentation just described, 
 but rather a pale fundus or one resembling a slow 
 or low grade of inflammation of the retina, and 
 choroid, with here and there scattered dots of pig- 
 ment. Several members of the same family may 
 have the condition, which suggests that it is con- 
 genital and possibly due to consanguinity of the 
 parents. There is no treatment of any avail. 
 
PLATE VIII. 
 
 PARTIAL DETACHMENT OF THE RETINA. FUNDUS OF THE RIGHT EYE. 
 DIRECT METHOD. 
 
 Mr. M. Aged 46 years. Patient seen in consultation by Dr. G. 
 E. de Schweinitz. 
 
 History of Myopia. Always carefully refracted. Was struck on 
 the left side of the head some few days before coming under obser- 
 vation. 
 
 Fundus Changes. Retina detached downward and forward. The 
 wavy condition of the retina, the course of the dark-colored vessels 
 without their usual light streaks, as they appear on the detachment, 
 are all quite characteristic of the condition under consideration. 
 The disc appears foggy because it is out of focus as compared with 
 the detachment, which is in focus for purpose of sketching. The 
 disc is seen with 7 D., whereas the detachment is best seen with 
 a + I D- Two most peculiar and irregular white streaks with pig- 
 ment massings on their upper edges are seen down and out and 
 down and in, beginning a short distance from the disc and extend- 
 ing as far forward as the eye can see into the periphery. These 
 white streaks resemble obliterated vessels or ruptures in the choroid, 
 and what is still more peculiar each eye has the same condition 
 and in about the same situation. There is no detachment in the 
 left eye. The white streaks are very likely congenital and possibly 
 obliterated vessels. A rupture of the choroid would be crescentic 
 in shape and situated elsewhere in the fundus, and it is not likely 
 that there would be two ruptures in the same eye or in both eyes. 
 Each eye has compound myopic astigmatism. 
 
 See chart, Fig. 72. 
 
 Vision of right eye IV/L with 5.25 D. C 1-25 Cyl. axis 20 
 degrees = l prism b. d. == VI/VI. 
 
 Vision of left eye IV/CXX with 8.25 D. Z 3-25 Cyl. axis 
 165 degrees = i prism b. up. = VI/VI. 
 
 216 
 
PLATE VIM 
 
 Detachment of the Retina 
 
OPHTI-IALMOSCOPIC FINDINGS. 2IQ 
 
 Detachment of the Retina. This means that 
 the retina is no longer held up against the choroid 
 by the vitreous, the latter having become diseased 
 or some force greater than the vitreous pressure, has 
 been exerted from behind and the retina has come 
 forward as a consequence. This may occur in any 
 part of the retina either as a partial condition 
 (Plate VIII.) or as a total detachment; this latter 
 is sometimes spoken of as an umbrella detachment, 
 in its resemblance to a closed umbrella, the retina 
 remaining attached at the disc edges and the ora 
 serrata. 
 
 Ophthalmoscopic Findings. Viewing a fundus 
 having a partial detachment, the normal reflex is 
 absent at the portion detached and in its place is 
 seen a reflex more or less opaque and gray in color 
 with its surface uneven and more or less wavy. The 
 retinal vessels passing over the detachment are quite 
 dark, or blue-black in color, and have lost their 
 light streak, they have peculiar positions or curves 
 or bends which are in keeping with the surface of 
 the detachment, they appear decidedly serpentine. 
 The same lens in the ophthalmoscope will not focus 
 the same or any one vessel in all of its various posi- 
 tions. If the eyeball is rotated in different direc- 
 tions the detachment with its vessels are seen to 
 move according to the fluidity of the vitreous and 
 underlying fluid. When the retina is totally de- 
 tached, no view of the interior of the eye can be ob- 
 tained and the condition can best be examined by 
 
22O 
 
 THE OPHTHALMOSCOPE. 
 
 having the pupil dilated and using the oblique 
 light. Detachment usually affects one eye alone, 
 though both eyes may become affected, one eye 
 before the other; seldom are both eyes affected 
 primarily at the same time unless from injury. 
 Occasionally it is the upper part of the retina that 
 detaches first and the fluid behind gradually 
 gravitates downward and in this way the part first 
 detached may settle back to its normal position and 
 
 FIG. 72. Form Field, showing the upper field cut off abruptly and also 
 considerable contraction down and out. This is the chart of the patient 
 with Partial Detachment of the retina in right eye, as illustrated in 
 Plate VIII. 
 
 the lower part becomes the detached portion. The 
 detached retina soon becomes blind. Sooner or 
 later, depending upon the amount of the detach- 
 ment, the lens becomes opaque and the eyeball re- 
 mains quite soft. 
 
CAUSES OF DETACHMENT. 221 
 
 I 
 
 Visual acuity is not materially interfered with 
 unless the detachment is very large or involves 
 the macular region or the vitreous or lens become 
 cloudy. The field of vision is lost in the area cor- 
 responding to the detachment, and it is often this 
 one symptom which brings the patient under ob- 
 servation (see Chart, Fig. 72). 
 
 Causes of Detachment. The most common 
 cause is myopia (the stretching eyeball). Other 
 causes are inflammation of the retina; or ciliary 
 body; or uveitis; cysticercus; injuries; tumors of 
 the choroid; diminished intra-ocular tension fol- 
 lowing the removal of the lens on account of high 
 myopia, loss of vitreous from any cause and also 
 diminution in the density of the vitreous as seen in 
 diabetes, etc., and also from a pulling on the retina 
 by cicatricial bands. Detachment of the retina may 
 develop suddenly from straining at stool or after 
 stooping over or after running or after any great 
 exertion. A patient of the writer's developed or 
 noticed sudden loss of sight in the lower field after 
 a violent spell of sneezing and a detachment was 
 carefully studied and mapped out two hours later. 
 Retinal detachment is said to be much more common 
 among men than women. 
 
 Differential Diagnosis. Detachment due to 
 fluid and that due to a neoplasm should have careful 
 consideration as bearing upon the life of the pa- 
 tient. A growth beneath the retina would give a 
 somewhat similar picture to that of detachment as 
 
222 THE OPHTHALMOSCOPE. 
 
 far as the curves in the vessels are concerned, but 
 they would very likely maintain their light streak 
 which they would not do in a fluid detachment, and 
 there would not be that wavy appearance to the 
 retina and vessels as in the fluid detachment, neither 
 would there be that motion to the detachment when 
 the eyeball was suddenly rotated, and furthermore 
 when the retina is raised up by a growth from the 
 choroid it has more definite or sharply cut edges, 
 as compared to a detachment from fluid. 
 
 Elevation of the Detachment. The detachment 
 of the retina whether due to fluid or a growth means, 
 that the retina in the area of detachment is brought 
 closer to the crystalline lens, and therefore to study 
 or examine it carefully a much stronger plus lens 
 must be employed at the sight-hole of the ophthal- 
 moscope if the eye is naturally hypermetropic than 
 would be required to see the disc, and if the eye 
 was myopic then a weaker minus lens or very likely 
 a plus lens would have to be employed to see the 
 vessels on the detachment. The difference in the 
 strength of the lenses employed to see the surround- 
 ing attached retina and the top of the detachment 
 represents the amount of the elevation, depending 
 of course upon the position of the growth or loose 
 retina, whether well forward in the eye ground or 
 back near the disc. Every three diopters of differ- 
 ence represents one millimeter of elevation. The 
 field of vision and the elevation carefully studied 
 at different times and then compared, will be a 
 
TREATMENT OF DETACHMENT. 223 
 
 guide as to the increase or decrease in size of the 
 detachment or growth. 
 
 Prognosis. Most unfavorable for permanent 
 reattachment. Usually the detachment becomes 
 complete and sight destroyed. 
 
 Treatment. Enucleation of the eye, if the de- 
 tachment is due to a growing tumor. If due to 
 fluid, and the patient comes under observation quite 
 early, then the patient must be placed in the recum- 
 bent position, atropin instilled and the eye gently 
 bandaged. The patient must be freely purged and 
 following this pilocarpin sweats must be given 
 every night or every other night, according to the 
 patient's condition and according to the changes 
 whch take place in the eye. Subconjunctival injec- 
 tions of normal salt solution should be given every 
 second or third day. Internally the patient should 
 receive increasing doses of the iodid of potash. The 
 eye ground should be studied briefly each day to see 
 if the fluid is diminishing and the retina resuming 
 its normal position; when this has been accom- 
 plished the patient should remain comparatively 
 quiet for several days before attempting any move- 
 ments like walking up and down stairs. The treat- 
 ment by tapping the fluid through the scleral coat 
 and drawing off the fluid, and then injecting irri- 
 tants like the tincture of iodin, etc., is not considered 
 advisable ; all such treatment has been tried and ulti- 
 mate failures reported. Most every case treated 
 has failed of permanent reattachment, yet as some 
 
224 THE OPHTHALMOSCOPE. 
 
 few recoveries have been reported, the treatment 
 should be carried out in each case, especially if seen 
 quite early ; the earlier the case comes under obser- 
 vation the better. 
 
 Rupture of the Retina. This is a most unusual 
 condition, though it has been recognized. A rup- 
 ture of the retina accompanying a corresponding 
 condition of the choroid is not so infrequent. If 
 the retina is ruptured its ragged edges will be seen 
 and also the exposed choroid beneath; of course 
 if a hemorrhage occurs at the time of the rupture 
 then the wound may be covered, but as soon as the 
 hemorrhage is absorbed the diagnosis can be made. 
 The retina is liable to rupture after being detached, 
 therefore it may be a sequela of detachment of the 
 retina. 
 
 Commotio Retinae, or Contusion of the Retina. 
 A severe blow upon the eyeball or the head with a 
 blunt instrument such as a ball, club, fist, etc., will 
 produce impaired vision, redness of the eyeball, and 
 dread of light (photophobia). These symptoms 
 will ordinarily pass away in a few hours unless 
 unusually severe. For the time being, however, the 
 ophthalmoscope reveals a slight opacity of the 
 retina. A guarded prognosis should be given, for 
 if the condition persists for some time, it may 
 eventuate in impaired vision which may become 
 permanent. 
 
 Glioma of the Retina (also called " Amaurotic 
 Cat's Eye). This is a disease of the retina which 
 
GLIOMA OF RETINA. 225 
 
 occurs in infancy, very seldom after the age of six 
 years, though a case has been reported which oc- 
 curred as late as twelve years. Glioma is therefore 
 recognized as a disease of infancy, a congenital con- 
 dition, and has been known to affect more than one 
 child in the same family. It usually affects one eye, 
 but may appear in both. " Glioma is the only neo- 
 plasm which occurs in the retina." (Fuchs.) Gli- 
 oma is a non-pigmented growth springing from the 
 inner granular layer of the retina, and grows rap- 
 idly. The child is usually brought under observa- 
 tion with the statement from the mother or some 
 member of the family, that a glistening reflex from 
 the eye has been noticed for a certain length of 
 time and that the child did not appear to be seeing 
 with the eye or on the side corresponding to the 
 eye affected. Hence the name amaurotic (d/taupd?, 
 dark or blind). 
 
 Ophthalmoscopic Findings. No definite fun- 
 dus reflex can be made out unless the eye is 
 brought under observation quite early, but no 
 matter whether seen early or in the late stage of 
 the disease, it will be necessary to examine the eye 
 with the oblique light and have the pupil dilated. 
 The glioma is usually of a whitish-pink color and 
 may be irregular, lobulated or smooth. 
 
 Growth of the Glioma. This is quite rapid as a 
 rule, and especially so after the first stage which is 
 that of loss of sight and increase of tension; then 
 comes great pain and the growth perforates the 
 
226 THE OPHTHALMOSCOPE. 
 
 eye in different places, usually at the nerve and the 
 edge of the cornea. The orbit becomes crowded 
 and the bleeding mass protrudes between the lids 
 and onto the cheek. By metastasis and continuity 
 of structure, the disease spreads to the internal 
 organs and the brain. The patient wastes away 
 and dies. 
 
 Differential Diagnosis. Glioma resembles 
 pseudo-glioma (purulent choroiditis) which is not 
 a malignant disease. It also resembles tubercle of 
 the choroid (see choroidal diseases). 
 
 Glioma. Pscudo-Glioma. 
 
 Pinkish-white color. Yellow or straw color. 
 
 Smooth or tabulated surface. Flat surface. 
 
 Iris usually pushed forward. Iris adherent posteriorly in most 
 
 instances, and its ciliary bor- 
 der retracted. 
 
 Anterior chamber shallow. Deep anterior chamber. 
 
 May appear vascular. Does not appear vascular. 
 
 Tension may be very much in- x Tension diminished, 
 creased. 
 
 Prognosis. Unfavorable unless the eye is 
 enucleated early. The prognosis is favorable, if 
 the glioma does not return within three years after 
 removal. 
 
 Treatment. Early enucleation and dividing the 
 nerve as far back as possible. 
 
 Retinitis Circinata (Described by Fuchs). The 
 retinal picture of this disease as seen with the oph- 
 thalmoscope is that of a number of glistening white 
 patches which are arranged in the form of an oval 
 about the macula, extending well upward and 
 
AMAUROTIC FAMILY IDIOCY. 227 
 
 downward almost to the temporal vessels. Occa- 
 sionally the retinal vessels are seen to pass over 
 these white patches which resemble the patches seen 
 in albuminuric retinitis and diabetes. Occasion- 
 ally a few hemorrhages are seen in the white 
 areas. The macula is usually involved and its 
 visual quality is very much reduced. This 
 seems to be a disease of the macular region, as the 
 rest of the eye ground appears normal. For- 
 tunately, this is a rare disease and is usually found 
 among the aged. There is no relief for the condi- 
 tion and fortunately total blindness seldom occurs. 
 Amaurotic Family Idiocy, Symmetric Changes 
 at the Macula Lutea in Infancy. The infant is 
 usually of Hebrew parentage. A most unusual 
 disease and not many cases recorded. It was first 
 described by Warren Tay. The ophthalmoscopic 
 picture is one which resembles embolism of the cen- 
 tral artery. In this disease the macula lutea is 
 very conspicuous by being cherry red and of much 
 larger area than the red spot of embolism ; it is im- 
 mediately surrounded by an area of gray white- 
 ness about the size of the disc or a trifle larger. 
 The rest of the eye ground appears normal, all 
 except the disc, which soon becomes atrophic. As 
 its name indicates, it is a disease of infancy. The 
 infant seldom reaches its third year. Disease of 
 the brain and spinal cord accompany the eye condi- 
 tion. This disease is caused by an arrest of devel- 
 opment and changes are found in the ganglion 
 
228 THE OPHTHALMOSCOPE. 
 
 cells of the retina, of the cortex, and degeneration 
 of the cord. 
 
 Purulent Retinitis. This, like purulent choroid- 
 itis, is due to septic emboli, and the two conditions 
 generally appear together. The ophthalmoscope 
 shows numerous hemorrhages and many white or 
 yellowish-white opaque spots, which soon become 
 diffuse and the vitreous becomes cloudy (see Puru- 
 lent Choroiditis). 
 
 Angioid Streaks. Pigment streaks in the retina. 
 This is a very rare condition affecting both retinas. 
 The vision is somewhat diminished. These streaks 
 are recognized as being in the deep layers of the 
 retina, as the retinal vessels are seen to pass over 
 them. The first impression is, that these streaks are 
 obliterated vessels which they resemble. They are 
 brownish in color, irregular in outline and not sym- 
 metric. There is no treatment. 
 
CHAPTER IX. 
 
 DISEASES OF THE OPTIC NERVE. 
 
 DISEASES of the optic nerve are recognized by 
 the patient's symptoms, the field of vision, the 
 visual acuity and a study of the optic disc which 
 is the only part of the nerve that can be seen with 
 the ophthalmoscope. The study of the pathologic 
 disc therefore requires a knowledge and apprecia- 
 tion of the normal disc and an intimate acquaint- 
 ance with the anatomic construction of the part 
 and parts concerned (see Chapter III.). The 
 disc itself is nourished by the capillary branches 
 from the central and posterior ciliary arteries 
 which make up the circle of Haller. The central 
 vessels (except the capillaries just mentioned) on 
 the disc are terminal vessels and go to nourish the 
 retina. The transparent nerve fibers in their re- 
 spective bundles pass through the openings in the 
 membrana cribrosa ; these openings act like so many 
 collars around the nerve bundles, if therefore from 
 any cause these nerve fibers become swollen or in- 
 flamed, then the membrana cribrosa acts like liga- 
 tures and the resulting conditions as seen with the 
 ophthalmoscope must be in keeping with the degree 
 of swelling and constriction exerted. 
 
 Color of the Normal Disc. This has already 
 
 229 
 
230 THE OPHTHALMOSCOPE. 
 
 been described in Chapter IV., but there is ample 
 room for dispute by the best authorities as to slight 
 changes from the normal complexion or what repre- 
 sents the normal color for a certain disc in a cer- 
 tain fundus, and frequently the surgeon must make 
 examinations on different days before committing 
 himself to an opinion that might otherwise be 
 erroneous. 
 
 Hyperemia of the Disc. The normal disc is 
 said to be pink or yellowish-red in color (Plate I.) ; 
 then if the disc appears red in color it is said to be 
 hyperemic; some authorities call this "peach red," 
 " cinnabar red," " brick dust red," etc. If the 
 hyperemia is of moderate amount the edge of the 
 disc may be easily distinguished, but if the hyper- 
 emia is excessive or is increasing, the disc becomes 
 indistinct or possibly obscured, and the disc edges 
 cannot be definitely distinguished from the sur- 
 rounding eye ground except by following the ves- 
 sels to their central convergence. 
 
 Pallor of the Disc. This is a condition the very 
 reverse of hyperemia. The color of the disc in place 
 of being normal in color will appear chalky white, 
 as the very extreme condition of pallor. Slight 
 degrees of pallor are not readily distinguished, 
 and considerable practice is required for a positive 
 opinion, and frequently other conditions must be 
 taken into consideration before deciding positively. 
 Pallor of the disc due to anemia gives the rest of 
 the eye ground a pale appearance also, whereas 
 
DEPRESSIONS OF DISC. 231 
 
 when the disc is chalky white in color, the surround- 
 ing eye ground appears redder than normal, and 
 this is brought about by contrast (Plate X.). 
 
 Changes or Alterations in the Surface Level 
 of the Disc, as compared with the adjacent eye 
 ground. The disc may appear level with the sur- 
 rounding eye ground or depressed in whole or in 
 part, or it may appear elevated. 
 
 Depressions. These may be classed as three, 
 the physiologic cupping, the glaucoma cup and the 
 depression from atrophy (saucer cupping). This 
 term 'saucer cupping' is really a misnomer, and 
 saucer excavation is a better one. 
 
 In the study of an elevation or depression of the 
 disc three methods may be followed: first, the ves- 
 sels are carefully studied in their course as they 
 adapt themselves to the surface on which they lie. 
 As an elevation or depression is a gradual ascent or 
 descent, then the course of the vessel will appear 
 gradually changed, whereas, if the elevation or de- 
 pression is abrupt the course of the vessel will appear 
 more or less sharply bent. If the alteration from 
 the level is gradual, then the vessel may be continu- 
 ously traced, but if the alteration from the level is 
 abrupt the vessel will have the appearance of being 
 broken, or it appears to stop abruptly and then to start 
 again at a different level (Plate XIL). Second, the 
 proof of the difference in level is made evident when 
 the observer has to employ a different strength lens 
 in the ophthalmoscope to see the vessel clearly in 
 
232 THE OPHTHALMOSCOPE. 
 
 its different positions or levels ; for instance, a ves- 
 sel at the edge of the disc may be seen clearly with 
 a + 5 D. in the ophthalmoscope, and at the same 
 time the same vessel will appear hazy or indistinct 
 at the bottom of the cupping, and might require a 
 minus lens to bring it into view at that point. It is 
 much better to select small vessels for this test as 
 they usually lie closer to the surface, and at the 
 same time require a little more delicate focusing. 
 Third, the parallax test (Chapter IV.). 
 
 1. Physiologic Cupping (see Chapter IV.)- 
 Fig. 73, No. i, is a drawing of the disc, showing 
 physiologic cupping, and illustrates the manner in 
 which the vessels pass in and out of it, conveying 
 the idea of how the nerve level is depressed with 
 the cupping. 
 
 2. Depression from Glaucoma Cupping (Plate 
 XII. ). This cupping represents an excavation of 
 the entire nerve head or disc, and is produced by 
 intra-ocular pressure; in other words, the nerve 
 head is pressed backward into the scleral ring. The 
 edge of the cup is steep, precipitous and even over- 
 hanging. The disc varies in color in different 
 cases, and is therefore variously described as 
 greenish, gray, grayish-blue or white. The vessels 
 in the retina appear to stop suddenly as they pass 
 over the edge into the cup, and then may reappear 
 out of focus at the bottom of the cup. The arteries 
 are smaller in caliber and the veins are full and tor- 
 tuous, sometimes having the appearance of a string 
 
DEPRESSION FROM GLAUCOMA CUPPING. 233 
 
 of beads. When the edge of the disc is clearly fo- 
 cused and the ophthalmoscope is tilted so that the re- 
 flected light passes across the disc, the bottom of the 
 cupping appears to have a different rate of move- 
 
 ment; this is called the glaucomatous parallax. 
 Plate XII. shows the apparent sudden termination 
 of the retinal vessel at the edge of the disc, and 
 also the same vessel dimly seen in the bottom of the 
 
 20 
 
234 THE OPHTHALMOSCOPE. 
 
 cupping. Fig. 73, No. 3, is a section of a glaucoma- 
 tous cupping and shows the steep or overhanging 
 walls of the cup. 
 
 3. Depression of the Disc from Atrophy. This 
 form of depression, like the glaucomatous, extends 
 over or embraces the entire disc, but unlike the glau- 
 comatous, it is shallow and the depression is very 
 gradual from edge to center, not abrupt like a cup, 
 but gradual like a saucer ; hence it is spoken of as a 
 saucer excavation in contradistinction to the cup- 
 ping excavation. The vessels on the disc, there- 
 fore, do not stop abruptly and then reappear, but 
 pass gradually from the edge to the center. In the 
 early stage of atrophy, the arteries are small and the 
 veins are full, but in the late stage of atrophy (com- 
 plete) both arteries and veins are very much dimin- 
 ished in calibre and cannot be readily distinguished 
 from each other by the light streak, as in the normal 
 eye. The color of the disc in this last stage of 
 atrophy is white or chalky, sometimes spoken of as 
 bluish-white, or the color of skimmed milk. This 
 color extends to the edge of the disc. Plate X. 
 shows the white disc, and Fig. 73, No. 2, a section 
 illustrating the gradual saucer curve, or bow shape, 
 to the disc. 
 
 To summarize: 
 
 Physiologic Cupping Glaucoma Cupping 
 
 (Fig. 73, No. i). (Fig. 73, No. 3)- 
 
 I. Cupping is central or to tern- I. Cupping entire, 
 poral side. Shelving from 
 the side. 
 
ELEVATION OF DISC. 235 
 
 Physiological Cupping. Glaucoma Cupping. 
 
 2. Cupping gradual or abrupt. 2. Cupping has abrupt edges. 
 
 3. Vessels normal. 3. Veins full, arteries small. 
 
 4. Parallax occasionally marked. 4. Parallax very marked. 
 
 5. Normal color of disc. 5. Gray or pearly white color of 
 
 disc. 
 
 A trap hie 
 (Fig. 73, No. 2). 
 
 1. Depression is entire. 
 
 2. Gradual sloping. 
 
 3. Arteries and veins indistinguishable. 
 
 4. No parallax. 
 
 5. Disc white in color. 
 
 Elevation of Disc, the Swollen Disc. This is 
 the very reverse of the three conditions just de- 
 scribed. This is spoken of as optic neuritis, papil- 
 litis, choked disc. Remembering the anatomy of 
 the parts, how the sheath of the optic nerve is con- 
 tinuous with the sclerotic coat, and between the 
 nerve and its sheath is the arachnoid space, how the 
 fibers of the nerve with artery or arteries and veins 
 passed through the membrana cribrosa, then any 
 portion of the nerve lying in front of the mem- 
 brana cribrosa, must become constricted by this 
 membrana cribrosa during inflammation of the 
 nerve fibers, and this therefore means a compres- 
 sion or squeezing of the disc, and hence its name 
 "choked disc," papillitis, or optic neuritis. If the 
 disc swells, it must project forward into the vitreous 
 and also laterally. The swelling of the disc, whether 
 due to pressure on the nerve fibers while in the 
 nerve sheath before entering the scleral openings, 
 or from obstruction to venous or arterial blood, or 
 
236 THE OPHTHALMOSCOPE. 
 
 by infection or proliferation; no matter what the 
 cause, the condition is the same in all, viz., swelling. 
 The presence of the swollen or elevated nerve head 
 can be proven by the different strength lens re- 
 quired in the ophthalmoscope to see first the top of 
 the disc and then the edge of the disc or the sur- 
 rounding eye ground. The swollen nerve head is 
 composed of nerve fibers, inflammatory products, 
 contracted arteries and very full veins. The di- 
 ameter of the nerve head must therefore be much 
 greater than normal; three times its normal diam- 
 eter has been reported. The nerve fibers, as they 
 pass from the disc, are seen to be swollen for some 
 distance beyond its normal edge. They are opaque 
 and gray in color. The edge of the disc is no longer 
 clear cut but rather indefinite and merges gradu- 
 ally into the surrounding fundus. The margin of 
 the disc is spoken of as foggy, misty or woolly. 
 The veins are full and tortuous, as the return blood 
 from the retina cannot get out of the eye on account 
 of the swelling. The arteries on the disc and in 
 the retina are smaller for the same reason that the 
 veins cannot carry the blood from the eye, so the 
 arterial blood cannot get into the eye. The veins 
 are more or less covered by inflammatory products 
 and in some places they may be completely covered, 
 or here and there come into view but are rarely 
 seen distinctly. The arteries are often so small in 
 caliber as to appear like threads and are seen with 
 difficulty, or possibly cannot be seen at all. The 
 
CONSTRICTION OF CIRCULATION. 
 
 swollen nerve head may be described or considered 
 in three stages, the stage of swelling or constriction 
 of the circulation ; stage of effusion ; stage of reso- 
 lution, or absorption and atrophy. 
 
 Stage of Swelling or Constriction of the Cir- 
 culation. The elevation or swelling, while it may 
 be, and often is, irregular, slopes gradually down- 
 ward from the center into the surrounding eye 
 ground and the blood vessels follow the same slopes. 
 The nerve fibers are swollen and more or less 
 opaque and give the nerve head a striated appear- 
 ance. The disc margin, if it can be seen, is very 
 indistinct or foggy, not definite or clear cut. The 
 color of the disc is variously described as " red- 
 dish-gray," " brick dust red," and even as violet 
 and bluish. The veins are dark or almost black in 
 color, full and tortuous. The arteries are small 
 and do not carry much blood. This is the first 
 stage of optic neuritis, or choked disc, or papillitis. 
 The height of the swelling is calculated by the 
 strength of lens in the ophthalmoscope required to 
 see the top or apex of the swelling, as compared 
 with the strength of lens required to see the sur- 
 rounding eye ground, each three diopters represent- 
 ing very closely one millimeter of elevation. 
 
 Stage of Effusion or Cell Proliferation. The 
 swelling of the disc is now quite regular, and the 
 striation is not nearly so well marked. The effusion 
 or exudation extends well beyond the disc margin, 
 giving a decided opaque appearance which blurs 
 
238 THE OPHTHALMOSCOPE. 
 
 or obscures all fine detail observations. The central 
 vessels are more or less concealed by the effusion 
 and the arteries may not be seen. The color of 
 the disc is not now as red as in the first stage, but 
 is a dirty gray, and hemorrhages of varying sizes 
 and shapes may be seen on and around the disc, and 
 through the eye ground. 
 
 The Stage of Resolution or Absorption and 
 Atrophy. As the inflammation gradually subsides 
 the swelling diminishes and the effusion is very 
 slowly absorbed. The veins become less tortuous 
 and their color less dark. They also diminish in 
 caliber. The arteries remain thread-like and some 
 of them may not be seen at all. The color of the 
 disc is entirely white, or the color of chalk, and 
 may appear glistening. This is the declining or 
 final stage of optic neuritis. The surrounding eye 
 ground shows faint and irregular pigmentation; 
 this is often quite marked at the edge of the disc 
 (Plate IX.). 
 
 Optic Neuritis. There are several varieties of 
 neuritis named principally, from the anatomic parts 
 or part of the nerve involved. 
 
 Papillitis. Inflammation of that portion of the 
 nerve which is anterior to the membrana cribrosa, 
 or an inflammation of that portion of the nerve 
 which can be seen with the ophthalmoscope. 
 
 Papillo-retinitis. Papillitis associated with 
 retinitis. 
 
 Ascending Neuritis. This is an inflammation 
 
PAPILLITIS. 239 
 
 which starts at the eye and extends or ascends 
 toward the brain. Descending Neuritis is the re- 
 verse of the ascending variety, the inflammation 
 starting in the brain or back of the eye and de- 
 scending toward the eye. An inflammation of the 
 nerve back of the eye, is spoken of as retro-bulbar 
 .neuritis. A partial neuritis is an inflammation of 
 a part and not the whole of the nerve. 
 
 Papillitis, also called Choked Disc, Neuritis, 
 Intra-ocular Optic Neuritis. This begins as a 
 hyperemia of the disc and passes into a stage of 
 swelling so that the disc projects into the vitreous 
 and its apex is seen with a different strength lens 
 than is required to see the surrounding eye ground. 
 According to Untoff, the elevation of the disc 
 should be about two-thirds of one millimeter before 
 it is spoken of as choked disc. The disc is also seen 
 to be two or three times its normal width. The 
 physiologic cupping, if previously present, is now 
 absent. Hemorrhages, few or many, may be seen 
 in and about the disc and occasionally throughout 
 the fundus. The arteries and veins are seen to 
 pass down from the apex or summit of the swollen 
 disc and to bend abruptly to the level of the sur- 
 rounding eye ground. The arteries are so crowded 
 or pressed upon that the blood cannot pass through 
 into the eye, and naturally they maintain more or 
 less of their straight course, and on account of the 
 same pressure the veins become full, swollen and 
 tortuous because the blood cannot get out of the 
 
240 THE OPHTHALMOSCOPE. 
 
 eye and must remain backed up in the veins. The 
 veins get so full and tortuous as to appear like half 
 circles (-Plate III.) or serpentine, and hence the 
 name of "medusa nerve," given to the veins and 
 disc. 
 
 Papillitis usually appears in both eyes, but may 
 occur in one and when seen in one eye alone it may 
 be due to a local cause in the same orbit, and this 
 should be carefully looked for. If the cause is not 
 local then tumor of the brain may be diagnosed 
 with considerable certainty, and as being on the 
 side of the brain corresponding to the eye affected. 
 Papillitis, while so suggestive of brain tumor, does 
 not indicate the portion of the brain implicated. 
 
 Vision and Visual Field. In papillitis the cen- 
 tral vision may be normal at first, but later on may 
 become affected (see footnote, page 18). In 
 rare instances central vision may be lost sud- 
 denly. The field of vision is irregular in the 
 periphery and the blind spot is enlarged. Color 
 vision may be affected and hemianopsia may be 
 present, under certain conditions. 
 
 Course of Papillitis. As the retina is in great 
 part a continuation of the optic nerve, it is difficult 
 to imagine a case of papillitis without some involve- 
 ment of the retina, and it becomes quite doubtful 
 if papillitis can exist " per se." In cases of choked 
 disc that recover the inflammation gradually sub- 
 sides and atrophy supervenes. The swelling dimin- 
 ishes in the disc and retina, the hemorrhages are 
 
CAUSES OF PAPILLITIS. 24! 
 
 absorbed without leaving any trace of their pres- 
 ence, unless quite large, when they occasionally 
 leave yellowish-white patches in the retina which 
 mark their previous existence. For a time the 
 veins and arteries may regain in great part their 
 normal positions and size, and may remain so if ex- 
 tensive atrophy does not follow. The disc may ap- 
 proximate the normal state also, but with irregular 
 edges and with scattered broken pigment massings. 
 This is an important part of the differential diagno- 
 sis between atrophy following choked disc (Plate 
 IX.) and atrophy following medullary or interstitial 
 neuritis (Plate X.) where the disc edges are clean 
 cut and well defined. Vision is usually very much 
 reduced and peripheral vision irregularly con- 
 tracted. 
 
 Causes of Papillitis. Of all the causes of papil- 
 litis by far the most common is tumor of the brain, 
 namely, gumma, sarcoma, fibroma, carcinoma, etc. ; 
 or to state the fact more definitely, no matter what 
 the size of the tumor in the brain may be, large or 
 small, or its variety or its location in the brain, 
 78 per cent, of cases of brain tumor develop papil- 
 litis as the most important symptom. The follow- 
 ing very interesting and instructive table "The 
 Papillitis Accompanying Brain Tumor," by John 
 E. Weeks, M.D., presented at the Section on Oph- 
 thalmology at the fiftieth annual meeting of the 
 American Medical Association held at Columbus, 
 Ohio, June 6 to 9, 1899, gives the percentages of 
 
242 
 
 THE OPHTHALMOSCOPE. 
 
 choked discs, resulting from tumor in the brain 
 and the locations of the tumors, etc. 
 
 Location. 
 
 6 
 K 
 
 ~ 
 
 o : | 
 c z 
 
 ** 
 
 Unilateral. 
 
 Double 
 Optic 
 Neuritis. 
 
 Per Cent. 
 
 Frontal lobes 
 
 64 
 
 12 
 
 4 
 
 48 
 
 80.7 
 
 Temporo-sphenoidal 
 
 24 
 
 9 
 
 O 
 
 1C 
 
 62.5 
 
 Motor area 
 
 m 
 
 46 
 
 7 
 
 64 
 
 SQ. 2 
 
 Parieto-occipital 
 
 77 
 
 4 
 
 7 
 
 26 
 
 87.8 
 
 Brain surface 
 
 17 
 
 4 
 
 O 
 
 
 60.2 
 
 Centrum ovale 
 
 58 
 
 17 
 
 2 
 
 TO 
 
 70.7 
 
 Corpora quadrigemina 
 
 10 
 
 o 
 
 o 
 
 IQ 
 
 IOO 
 
 Basal ganglia 
 
 36 
 
 1C 
 
 O 
 
 22 
 
 61.1 
 
 Multiple 
 
 jq 
 
 II 
 
 2 
 
 26 
 
 46.6 
 
 Corpus callosum 
 
 12 
 
 7 
 
 O 
 
 
 41.7 
 
 Pituitary body 
 
 18 
 
 
 O 
 
 
 SO 
 
 Pineal gland 
 
 i 
 
 I 
 
 o 
 
 o 
 
 O 
 
 Crura 
 
 c 
 
 I 
 
 o 
 
 4 
 
 80 
 
 Pons 
 
 So 
 
 20 
 
 c 
 
 2? 
 
 60 
 
 Cerebellum 
 
 164 
 
 21 
 
 
 170 
 
 87.2 
 
 Base of cranium 
 
 IO 
 
 I 
 
 o 
 
 
 oo 
 
 
 IO 
 
 
 
 II 
 
 8^.7 
 
 
 
 
 
 
 
 Totals 
 
 677 
 
 1 80 
 
 27 
 
 470 
 
 69.4 
 
 Among other causes of choked disc or papillitis 
 may be mentioned meningitis in any of its varieties, 
 especially the tubercular, occurring among children 
 as a rather frequent cause. The following have 
 been noted as causing papillitis, albuminuria, dia- 
 betes, rheumatism, brain abscess, hydrocephalus, 
 thrombosis of the cavernous sinus, acromegaly 
 (swollen pituitary body), aneurism, cysts, hemor- 
 rhage of the meninges and traumas. Papillitis has 
 been noted during typhoid fever, scarlet fever, diph- 
 theria, small-pox, erysipelas, syphilis, influenza, etc. 
 Sunstroke, disturbances of menstruation, lead and 
 
TREATMENT OF PAPILLITIS. 243 
 
 alcohol have also been recorded as causes, showing 
 that the causes of papillitis are very many and vari- 
 ous, and yet cases occur idiopathically. 
 
 Prognosis. No matter what the cause of the 
 papillitis, the prognosis must always be grave, for 
 the simple reason that the vision is always more or 
 less damaged, the one exception to this statement 
 being the toxic amblyopias, which may recover, 
 otherwise the underlying cause of the papillitis 
 (tumor of the brain, etc.) places the patient's life 
 in danger. 
 
 Treatment. The cause must be carefully sought 
 for and carefully treated. Patients having pap- 
 illitis due to syphilis must be brought promptly 
 under the influence of mercury and as soon as 
 this is accomplished iodids should be pushed 
 to iodism. Menstrual disorders should be cor- 
 rected when they are the underlying cause. 
 The alterative action of mercury and the iodids 
 is appropriate treatment in almost every in- 
 stance, with the exception of the tubercular. 
 When the papillitis is due to a growth the case 
 should have the opinion of a neurologist and 
 surgeon. 
 
 Neuro-retinitis, or Papillo-retinitis (Plate V.). 
 With swelling of the disc as described under Papil- 
 litis, the retina usually becomes involved and as this 
 membrane becomes swollen and opaque the retinal 
 vessels become more or less hidden in the swelling 
 and resulting exudates. Hemorrhages make their 
 
244 THE OPHTHALMOSCOPE. 
 
 appearance in the course of the vessels and have 
 flame-shaped edges as they lie in the nerve fiber 
 layer. Large and scattered areas of exudate make 
 their appearance, and also an irregular star-shaped 
 figure at the macula, not unlike the condition seen 
 in albuminuric retinitis. 
 
 The differential diagnosis between papillitis per se 
 or neuro-retinitis due to brain tumor and albumin- 
 uric retinitis is not always easy, and must be very 
 carefully studied before coming to a positive diag- 
 nosis. The addition of palsies of any of the ocular 
 muscles would strongly suggest a growth in the 
 brain while the absence of palsies and the presence 
 of albumen and casts in the urine would indicate 
 nephritis, though both conditions have been known 
 to exist in the same patient. 
 
 Retrobulbar Neuritis Acute and Chronic, 
 Medullary Neuritis, Interstitial Neuritis. This is 
 an inflammation of the optic nerve back of the eye- 
 ball and within the orbit, therefore anterior to the 
 optic foramen. 
 
 Acute Retrobulbar Neuritis. Early in the dis- 
 ease there are few ophthalmoscopic changes noted, 
 and when they do appear they are slight and may 
 be overlooked, viz., hyperemia of the disc with its 
 edges hazy. The diagnosis is made primarily from 
 rapidly failing vision (central) \vhich brings the 
 patient under observation; in such instances this 
 failure of vision may result in almost complete 
 blindness in a few days. 
 
CHRONIC RETROBUL13AR NEURITIS. 245 
 
 Causes. Syphilis (gumma) ; taking cold; rheu- 
 matism; methyl alcohol; quinin; autotoxemia; dis- 
 turbed menstruation ; diabetes ; periostitis ; injuries. 
 In some instances no cause can be found. In other 
 cases it may be caused by decayed teeth, growths, 
 pressure, ethmoiditis, etc. 
 
 Prognosis. This must be very guarded, though 
 many cases recover; yet some few do not. For- 
 tunately it is often a unilateral disease. 
 
 Treatment. This is the treatment of the cause. 
 
 Chronic Retrobulbar Neuritis, Tobacco Am- 
 blyopia, Toxic Amblyopia. Patients complain 
 of poor vision for near work which cannot be 
 materially improved with any glass, and state 
 that vision is apparently better on a dull or 
 cloudy day and is worse when the sun shines 
 brightly. The ophthalmoscope reveals almost a 
 normal fundus, unless the case is well advanced, 
 when the disc may appear pale in whole or in part. 
 
 The field chart may be quite normal for form, 
 but central scotoma for red and green is present; 
 this scotoma is usually the same in both eyes, hori- 
 zontally oval and extends from and including the 
 normal blind spot to the macula, showing the in- 
 fluence of the disease on what is known as the pap- 
 illomacular fibers, the nerve fibers passing from the 
 disc to the macula. 
 
 Causes. As its name implies (tobacco ambly- 
 opia, blunted sight from tobacco) this chronic 
 retrobulbar neuritis is frequently caused by over- 
 
246 THE OPHTHALMOSCOPE. 
 
 use of tobacco and very often this habit is associ- 
 ated with some moderate or excessive use of alcohol 
 in some form. The writer might state that there 
 is no rule or guide as to just how much smoking or 
 drinking will produce toxic amblyopia " What is 
 food for one is poison for another." Some men 
 can drink and smoke excessively and never develop 
 amblyopia, whereas another may develop ambly- 
 opia from only a moderate use of these toxic agents. 
 Tobacco amblyopia seldom develops before the age 
 of forty. Other substances that will produce the 
 same symptoms are essence of ginger, strong coffee 
 to excess, chloroform, opium, chloral, arsenic, iodo- 
 form, quinin, salicylic acid, acetanilid, caffein, bi- 
 sulphid of carbon, nitro-benzol, methyl alcohol 
 (wood alcohol), etc. 
 
 Prognosis. Favorable if due to alcohol and to- 
 bacco and the patient comes under observation early 
 and carries out the treatment. The prognosis must 
 be guarded in any instance and when due to causes 
 other than tobacco and alcohol the history of the 
 patient must have careful consideration. 
 
 Treatment. Stop the cause if possible. Pilo- 
 carpin sweats occasionally; strychnia in tonic doses 
 and the use of iodid of potash as an absorbent. 
 The patient must also be cautioned against return- 
 ing to the use of the drug or any drug which might 
 bring back a recurrence of the nerve condition. 
 
 Optic Nerve Atrophy. There is no portion of 
 the optic nerve exempt from this condition of 
 
PLATE IX. 
 
 ATROPHY OF THE OPTIC NERVE (Posr PAPILLITIC ATROPHY). ALSO 
 
 MEDULLARY NERVE-FIBERS. FUNDUS OF RIGHT EYE. 
 
 DIRECT METHOD. 
 
 Miss L. D. Aged 16 years. 
 
 History. Patient was treated for " Choked Disc " in 1901. Had 
 a tumor (gumma ( ?) ) of the brain. Patient treated by Drs. Mus- 
 ser, Spiller and Hermance. 
 
 Fundus Changes. Disc is bluish in color. The edges are not 
 well defined. Lamina cribrosa is not present. As a coincidence 
 there are medullary nerve-fibers present at the upper edge of the 
 disc. The whole fundus is peculiarly mottled (map-like). The 
 retina is atrophied and the macula cannot be distinguished. Arte- 
 ries are straight and some of the larger veins slightly tortuous. 
 Left eye similarly affected, but without the medullary fibers and not 
 such an extensive atrophy. 
 
 March 31, 1905. Vision of right eye with -f- i.oo Cyl. axis 100 
 degrees = light perception. 
 
 Vision of left eye with -f- i.oo Cyl. axis 80 degrees = VI/X. 
 
 248 
 
PLATE IX 
 
 Atrophy of the Optic Nerve 
 
 (Past Papillitic Atrophy) 
 Also. Medullated Nerve-fibers 
 
PLATE X. 
 
 PRIMARY OPTIC ATROPHY. (SPINAL ATROPHY.) FUNDUS OF RIGHT 
 
 EYE. DIRECT METHOD. FUNDUS OF LEFT EYE 
 
 ABOUT THE SAME. 
 
 Mr. William S. S. Aged 54 years. Dyer by occupation. 
 
 History. Vision has been failing gradually for two years. Has 
 been using various glasses to read with and now cannot read with any 
 glasses that he can purchase. His walk has been impaired for about 
 the same length of time that his sight has been failing him. His- 
 tory of syphilis. Uses tobacco and alcohol to excess. 
 
 Irises do not react to light stimulus, but do respond to conver- 
 gence and accommodation (Argyll-Robertson Pupils). 
 
 Fundus Changes. Vision of each eye about i/io. Disc bluish in 
 color and glistening. Membrana cribrosa is seen at the center of 
 the disc. The disc has a white edge, called by some a scleral ring. 
 A cilio-retinal vessel is seen on the temporal edge of disc passing 
 toward the macula. Fundus reflex apparently normal. Vessels arc 
 not particularly narrowed at the present time. Arteriosclerosis evi- 
 dent at crossing of vessels. Disc has " saucer " shaped excavation. 
 
 252 
 
PLATE X 
 
 Primary Optic Atrophy 
 
PRIMARY ATROPHY. 255 
 
 shrinking of its elements from the brain center up 
 to and including the papilla. There are three dis- 
 tinct forms of atrophy, primary, secondary and 
 consecutive. 
 
 Primary Atrophy. Spoken of as progressive, 
 degenerative, gray, spinal or tabetic atrophy (Plate 
 X.). This is an atrophy that appears without any 
 apparent or very slight previous inflammation. It 
 is usually bilateral. It may be a local condition of 
 one eye, but it is usually met with in locomotor 
 ataxia and disseminated sclerosis, therefore affect- 
 ing both eyes. Spinal disease (33 per cent.) is 
 the most common cause of gray degeneration of the 
 optic nerve, especially in locomotor ataxia. Among 
 other causes are, malnutrition, taking cold, dis- 
 turbed menstruation, syphilis, drugs, etc. ; and occa- 
 sionally the cause may be unknown. Hereditary 
 predisposition; this latter variety, if it may be so 
 called, has been known to appear in the male mem- 
 bers of a family generation after generation, and 
 to develop about the age of twenty-one years. 
 
 Secondary Atrophy. This means that the nerve 
 has degenerated by reason of some previous lesion, 
 such as fracture of the optic foramen, pressure on 
 the optic tract, etc., or a disease of the nerve or 
 retina, embolism of the central artery of the retina, 
 retinitis pigmentosa, retino-choroiditis, syphilitic 
 retinitis, glaucoma, etc. 
 
 Consecutive Atrophy. Also spoken of as post- 
 neuritic atrophy or post-papillitic atrophy. This is 
 
256 THE OPHTHALMOSCOPE. 
 
 the variety of wasting that follows an inflammation 
 like papillitis (Plate IX.). The terms secondary 
 and consecutive atrophy are often confused. 
 
 Ophthalmoscopic Appearances. To study the 
 different varieties of atrophy, it is well to employ 
 both the direct and the indirect methods. The two 
 principal characteristics of atrophy as seen with 
 the ophthalmoscope are paleness or whiteness 
 of the disc and a diminution in the vascularity. 
 The disc (principally the intermediate zone) 
 loses its normal pink or yellowish red color and 
 appears pale. It is the capillary circulation that 
 produces the shell pink color of the normal healthy 
 disc, and when this circulation is destroyed atrophy 
 must be present. It is not absolutely necessary to 
 have the large vessels of the disc diminished in 
 size to have atrophy, and sometimes the large ves- 
 sels do not perceptibly diminish in size until late in 
 the disease. It may also be stated that occasionally 
 the large vessels may diminish in size and atrophy 
 develop before the capillary circulation disappears 
 or lessens. The color of the disc in atrophy is not 
 the same in all eyes, and has been described as 
 white, chalky white, snow white, cottony white, 
 pearly white, gray, grayish-white, bluish, skim milk, 
 green, etc. These colorings are controlled in great 
 degree by (a) the reflected light, its quality, color 
 and intensity; (b) by the comparative color of the 
 surrounding eye ground; (c) by the presence or 
 absence of the physiologic or glaucoma cupping; 
 
OPHTHALMOSCOPIC APPEARANCES. 257 
 
 (d) by the membrana cribrosa, if present or ab- 
 sent; and also (e) by the character of the inflam- 
 mation previous to the atrophy. The colorings of 
 the nerve in atrophy cannot be attributed to pig- 
 mentation. Of course the observer's idea of color 
 must also enter into the description of the color of 
 the atrophic disc. The color of the atrophic disc is 
 not always uniform; the center may be stippled 
 white and gray, and the edge have a gray or green- 
 ish or bluish tinge (Plate X.), and so there are in- 
 numerable variations. 
 
 Causes. Most cases of locomotor ataxia are ac- 
 companied sooner or later by primary optic atrophy 
 and in fact optic atrophy may be a preataxic symp- 
 tom. Multiple sclerosis is another cause of pri- 
 mary optic atrophy, as also epilepsy and progressive 
 paralysis (see page 255). 
 
 Differential Diagnosis. Atrophy following 
 papillitis and primary atrophy are not the same in 
 all particulars, though they have many points of 
 similarity. 
 
 Primary Atrophy Atrophy from Papillitis 
 
 (Plate X.). (Plate IX.). 
 
 Disc very brilliant and glistening White color of disc, not bril- 
 
 white pearly white, or gray. liant; appears a dirty gray, 
 
 described as bluish. 
 
 Disc edges sharply cut. Disc edges not usually well de- 
 fined. 
 
 Lamina cribrosa very conspicu- Lamina cribrosa usually not con- 
 
 ous. spicuous. 
 
 Arteries and veins not so con- Arteries and veins very narrow ; 
 
 tracted. veins tortuous. 
 Excavation, if present, is saucer 
 shaped. 
 
258 THE OPHTHALMOSCOPE. 
 
 Diagnosis of Optic Atrophy. The ophthalmo- 
 scopic findings make the diagnosis quite easy when 
 the disease is well advanced, but if the disc has not 
 become decidedly pale, then other symptoms must 
 have careful consideration. The central vision may 
 remain good for quite a while whereas peripheral 
 vision may be concentrically contracted, the color 
 fields contracted and central scotoma evident. The 
 history of the patient is also of considerable im- 
 portance. 
 
 Prognosis. Unfavorable. The condition leads 
 to blindness in most instances. Of course the prog- 
 nosis must be controlled by the underlying cause. 
 Syphilitic cases appearing early give a fair prog- 
 nosis. In cases of locomotor ataxia, the atrophy 
 advances and blindness eventually takes place. 
 
 Treatment. This depends upon the cause. If 
 syphilis is suspected then mercury and iodids should 
 be prescribed and pushed to the point of tolerance. 
 When due to other causes, nerve stimulants, 
 strychnia by mouth and hypodermically, nitro- 
 glycerin, phosphorus, iron, etc., may be prescribed 
 as indicated and galvanism may be tried. 
 
CHAPTER X. 
 
 DISEASES OF THE CHOROID. GLAUCOMA. 
 
 DISEASES of the choroid, like diseases of the 
 retina and optic nerve, give defective vision as the 
 most important symptom to the patient, without any 
 external manifestations of the inward changes. It 
 is unfortunate for the patient that these structures 
 are not supplied with nerves of painful sensation 
 like the iris and ciliary body, so that the patient 
 would come under observation much sooner and 
 before serious damage to vision has resulted. Dis- 
 eases of the choroidal coat of the eye are indicated 
 with the ophthalmoscope by many changes from the 
 normal appearance of this tunic, namely: 
 
 1. Changes in the color of the eye ground. 
 
 2. Inflammatory products, patches of exudation, 
 and changes in elevation. 
 
 3. Changes in pigmentation. 
 
 4. Areas or white patches of exposed sclerotic 
 resulting from absorption of choroid and retinal 
 tissue. 
 
 Changes in Color. A diagnosis of hyperemia 
 of the choroid or disturbed choroid is not easily 
 made by the beginner in ophthalmoscopy, and it is 
 not until an infiltration has taken place which gives 
 the previously red reflex a yellowish tinge, that the 
 
 2 59 
 
26O THE OPHTHALMOSCOPE. 
 
 inflammation of the choroid is definitely recognized. 
 Fortunately, from a diagnostic point of view, in- 
 flammation of the choroid does not occur in the 
 whole choroid at one and the same time, but is seen 
 in scattered areas. 
 
 Inflammatory Products. Areas of exudation 
 may appear round or oval or irregular in form, 
 but they are usually oval in outline. These spots or 
 areas being pale yellow in color, are to be distin- 
 guished from an opaque or foggy retina. Patches 
 of recent choroiditis, while elevated are at a greater 
 depth, and at some few, or many points retinal 
 vessels may be seen passing over them, and they 
 are therefore elevated on these patches. Opacities 
 are sometimes seen floating in the vitreous, appear- 
 ing like dust particles, or threads. 
 
 Changes in Pigmentation. Another decided 
 characteristic of inflammation in the choroid is 
 the change in its pigmentation at and around the 
 spot of inflammation, and the retinal vessels are 
 often seen passing over these inflamed areas 
 which of course include the pigmentation if 
 the disease is advanced. The pigmentation is 
 never uniform, but is usually quite irregular, 
 sometimes rounded, sometimes crescentic; it is 
 brown or black in color giving the fundus the ap- 
 pearance of having had blots of ink scattered over 
 it. The number and character of these black spots 
 is usually in keeping with the number and size 
 of the areas of inflammation. Pigmentation is usu- 
 
ATROPHY. 26l 
 
 ally a late manifestation of an area of choroiditis. 
 Areas of choroiditis may be seen in various stages 
 of inflammation in the same eye ground. New 
 areas appear while others have reached the atrophic 
 stage. 
 
 Atrophy. This condition of the choroid natur- 
 ally follows absorption of the exudates at the areas 
 of inflammation, and is indicated by white areas 
 of irregular shape with scattered pigment at the 
 edges. Spots of atrophy (exposed sclera) stand 
 out in bold relief. It is not unusual to see a few 
 choroidal vessels passing through atrophic areas. 
 
 Hemorrhage of the Choroid, while it may take 
 place, and no doubt often does occur (when the 
 extensive vascularity of the choroid is taken into 
 consideration), yet hemorrhage of the choroid is 
 not easily recognized with the ophthalmoscope, as 
 the retinal layers hide them unless they are large 
 and very extensive, when they may break through 
 into the deep layers of the retina, or even into the 
 vitreous. 
 
 Inflammation of the Choroid (choroiditis) is 
 a very indefinite name unless qualified, so as to give 
 the variety and if possible the cause of the inflam- 
 mation. Furthermore, choroiditis has come to 
 mean not only an active inflammatory state, but a 
 condition of the choroid after the inflammation has 
 subsided. Choroiditis is said to be the most com- 
 mon of fundus diseases and only too frequently 
 it damages or destroys the sight. 
 
262 THE OPHTHALMOSCOPE. 
 
 The varieties of choroiditis are innumerable, and 
 have been variously classed, but each variety pre- 
 sents one or more of the characteristics just de- 
 scribed. Superficial and deep choroiditis are so 
 called on account of the part of the choroid af- 
 fected. The terms acute and chronic are self- 
 explanatory, and disseminated means that there 
 are several or many points or spots of inflammation 
 scattered through the choroid (Plate XL). If one 
 large area of the choroid is alone involved this is 
 called diffuse. Diffuse choroiditis (also called 
 deep choroiditis) may result from several dissemi- 
 nated areas enlarging and coming together. Cir- 
 cumscribed choroiditis means an inflammation 
 more or less limited in extent, whereas macular or 
 central choroiditis, while it may be circumscribed, 
 means an inflammation at the macular region. 
 Senile choroiditis, as its name indicates, is choroid- 
 itis in the aged and is usually a variety of central 
 or macular choroiditis. Recent and old choroiditis 
 are other names given to the acute and chronic 
 varieties, and atrophic choroiditis is but the final 
 stage of the disease. Myopic or posterior choroid- 
 itis is usually a choroiditis seen in eyes which have 
 a high myopic refraction, and, as its name implies, 
 is in the posterior part of the eye and usually 
 begins at the temporal side or edge of the disc, 
 and is called the myopic crescent from its fre- 
 quent resemblance to a crescent; or, if the cho- 
 roiditis surrounds the disc, it is called annular, 
 
PLATE XI. 
 
 RETINO-CHOROIDITIS (SPECIFIC). FUNDUS OF LEFT EYE. DIRECT 
 
 METHOD. 
 
 Mr. E. Aged 39 years. 
 
 History. Failing vision was noticed three days before coming 
 under observation. Thought it was only a cold in his eye, as he 
 had iritis and cyclitis as complications. 
 
 Fundus Changes. Nasal edge of disc hidden and cannot be dis- 
 tinguished from the neighboring retina. Temporal edge of disc is 
 clear and reveals a narrow crescent. A few yellowish-colored spots 
 seen in the choroid. Other spots of choroiditis have become absorbed 
 and white areas (atrophy) have taken their places with irregular pig- 
 mentations. The choroidal circulation is exposed in the periphery. 
 A large patch of retino-choroiditis is seen close to the temporal side 
 of the disc. Vision is very much reduced and the patient depends 
 on the vision of the right eye, which is VI/IX and was not so 
 seriously disturbed. 
 
 264 
 
PLATE XI 
 
 Retina- Charm ditis 
 
DISSEMINATED CHOROIDITIS. 267 
 
 and if there is any bulging backward of the sclerotic 
 coat, it is called a posterior staphyloma. Syphilitic 
 choroiditis is named from its cause and may mean 
 any one of the varieties mentioned, though the dif- 
 fuse or circumscribed variety is usually understood. 
 Disseminated Choroiditis (Plate XL). This 
 is recognized as the most common form of choroid- 
 itis. The spots of inflammation are scattered (dis- 
 seminated) over the eye ground chiefly in the 
 periphery. These areas are at first yellowish in 
 color, slightly elevated, more or less oval in shape. 
 As these inflammatory exudates become absorbed 
 the choroidal tissue is also absorbed or destroyed, 
 the white sclera showing in its place, and pigment 
 massings surround many of the irregular areas. 
 These areas of absorption have the appearance as 
 if parts of the choroid had been punched out by an 
 instrument which was not clean, and therefore had 
 left black edges. In other instances, or even in the 
 same choroid, the exudates may be replaced by a 
 large spot of pigment, or possibly by several spots 
 which may coalesce, forming one large, or several 
 large, patches. In some instances irregular figures 
 may be depicted. The choroid between the patches 
 is seen to be apparently healthy. The optic disc is 
 seen to be atrophic in the late stages of severe cho- 
 roiditis, and the term secondary optic atrophy has 
 been given to this condition. Both eyes are usually 
 affected, often one eye being affected in advance 
 of its fellow. 
 
268 THE OPHTHALMOSCOPE. 
 
 Causes. Syphilis is recognized to be the most 
 common cause of this disease whether acquired or 
 inherited. Other causes may be looked for in gen- 
 eral diseases, scrofula, anemia, chlorosis and also 
 in myopia. Sometimes the cause cannot be de- 
 termined. 
 
 Symptoms. These are principally those of de- 
 fective vision and as the retina and vitreous are 
 implicated the descriptions of the patient are in- 
 dicative of the structure or structures involved. 
 Floating specks indicate vitreous opacities, and 
 distortion of objects (metamorphopsia) when 
 the edge of a door frame or a straight line ap- 
 pears bent, indicates that the retinal elements 
 are separated or crowded together by being 
 raised up by an exudate. Central and peripheral 
 vision are impaired according to the amount 
 of structure disturbed and also its location in 
 the fundus. Scotomata are quite in evidence, but 
 not so annoying when in the periphery as when 
 they crowd upon the macular region. 
 
 Course of Choroiditis. This is usually a chronic 
 condition, taking many weeks or months for the 
 exudates to be absorbed. Atrophy of the retina 
 and the disc are liable to eventually make the case 
 worse, especially if the choroiditis has been exten- 
 sive. Cataract is not an infrequent complication 
 late in the disease. 
 
 Prognosis. This depends ( i ) on the portion of 
 the choroid involved, (2) on the extent of the in- 
 
TREATMENT OF CHOROIDITIS. 269 
 
 flammation, and (3) on the cause of the choroid- 
 itis. If the periphery of the choroid alone is in- 
 volved, central vision may remain good, but if the 
 inflammation involves the macula or its vicinity, 
 the prognosis for useful vision must be guarded. 
 When caused by syphilis, and the patient is seen 
 early and placed under prompt and vigorous anti- 
 syphilitic treatment, the case will be quite favorable 
 for useful vision if the macula has not been in- 
 volved. 
 
 Treatment. If caused by syphilis this must be 
 treated energetically with mercurial inunctions, 
 large and increasing doses of the iodids, pilocar- 
 pin sweats, etc. If the choroiditis is caused by 
 anything else, it must be treated according to its 
 cause. It is a noteworthy fact that no matter what 
 the cause, the alernative treatment with mercury 
 and the iodids is often the best treatment. This 
 should be borne in mind, as valuable time might be 
 lost if the physician was not on his guard in finding 
 the cause, or not disposed to believe that the indi- 
 vidual could be subject to syphilis. 
 
 Aside from the systemic treatment the eyes 
 should be protected from bright lights with dark 
 glasses, and the accommodation put at rest with a 
 properly selected cycloplegic. 
 
 Diffuse Choroiditis. (Also called deep and 
 exudative choroiditis.) This is practically a sub- 
 division of the disseminated variety. The ophthal- 
 moscope reveals large areas of yellowish-white 
 
270 THE OPHTHALMOSCOPE. 
 
 exudates ; these may be scattered or they may coal- 
 esce. If the retina becomes involved, as it often 
 does by contiguity of structure, the condition is 
 one of choroido-retinitis, and the opaque retina 
 adds its quota to the characteristic picture. In this 
 condition of choroido-retinitis pigment may be seen 
 here and there upon the retinal vessels. When ab- 
 sorption or atrophy of the yellowish areas takes 
 place, the sclera becomes exposed in large or small 
 areas with irregular patches of pigment at the 
 edges, or irregularly scattered. Often they assume 
 an oval or circumscribed appearance. 
 
 Course, prognosis and treatment are the same 
 for diffuse choroiditis as for the disseminated 
 choroiditis. 
 
 Central Choroiditis. (Also called macular or 
 senile.) This is usually a condition of both eyes. 
 As it involves the macular region the vision is usu- 
 ally seriously diminished, with resulting scotoma. 
 The disease is recognized in several varieties ; there 
 may be an atrophic patch with surrounding pig- 
 ment at the macula, or there may be a large white 
 area at the macula in which choroidal vessels may 
 be seen. Another variety is known as " Tay's 
 choroiditis" or " Tay's dots"; these are many 
 small, white, glistening dots (called senile guttate 
 choroiditis), and are due to colloid degeneration. 
 
 Causes. Trauma and syphilis and ametropia are 
 the commonly recognized causes. Senile choroid- 
 itis does not appear to be benefited by treatment. 
 
MYOPIC CHOROIDITIS. 2/1 
 
 When caused by syphilis and ametropia the treat- 
 ment is self-evident. 
 
 Myopic Choroiditis. Usually this is a very 
 serious condition, and means that the condition 
 has been brought about by a stretching or elonga- 
 tion of the eyeball and as its name indicated the 
 eye is myopic. The choroiditis begins usually or 
 almost invariably on the temporal side of the disc 
 and advances toward the macula and may destroy 
 it and pass beyond. The choroiditis may encircle 
 the disc at the same time. The choroidal vessels 
 become exposed, the retina atrophies and the pig- 
 ment becomes scattered irregularly. Vitreous 
 opacities are innumerable and of various sizes and 
 forms, the vitreous itself becoming quite fluid. 
 The vision is very much reduced and detachment 
 of the retina and the development of cataract may 
 soon complicate the already " sick " eye. The 
 treatment resolves itself into rest of the eye for all 
 near work, protection from bright lights, and care- 
 ful attention to the general health and later to 
 the correction of the refractive error with careful 
 instructions to the patient to use his eyes as little 
 as possible. Internally alterative treatment occa- 
 sionally does much good. 
 
 Colloid degeneration of the choroid, also called 
 guttate choroiditis, is an extremely rare condition 
 and is recognized as occurring in the macular 
 region. The ophthalmoscope reveals many round 
 elevated spots or bodies, placed close together, they 
 
2J 2 THE OPHTHALMOSCOPE. 
 
 are semi-transparent, and have been compared by 
 their resemblance to a mulberry. It is a condi- 
 tion of both eyes, but one of the eyes may be 
 more involved than its fellow. The vision is 
 often impaired. There is no treatment for the 
 condition other than prescribing the necessary 
 glasses. 
 
 Irido-choroiditis (also called panophthalmitis, 
 metastatic, purulent or suppurative choroiditis) is 
 an acute inflammation of the choroid pursuing a 
 rapid course, and caused by purulent matter being 
 carried into the choroid. No satisfactory study of 
 the choroid can be made out unless the disease 
 comes under observation quite early and yields 
 to prompt treatment. The areas of purulent exu- 
 date seen in the choroid soon coalesce and at the 
 same time the retina and vitreous become involved. 
 With a strongly reflected light a large yellowish 
 mass may be seen in the vitreous, and no clear view 
 of the fundus is made out. Iritis, cyclitis, etc., are 
 early manifestations which go to make up the true 
 picture of panophthalmitis. External manifesta- 
 tions of panophthalmitis are swollen lids, the con- 
 junctiva edematous and possibly protruding 
 between the lids, the cornea appearing to be buried 
 in the swollen conjunctiva. The patient complains 
 of pain and loss of sight, and the temperature is 
 elevated. 
 
 Causes. Purulent matter carried into the eye 
 by the blood vessels or germs entering the eyeball 
 
RUPTURE OF CHOROID. 273 
 
 from perforating wounds or ulcers. Puerperal 
 sepsis ; meningitis ; small-pox, etc. 
 
 Prognosis. This must be very guarded. Either 
 blindness with shrinking of the globe (phthisis 
 bulbi) or enucleation will be the usual and final 
 result of panophthalmitis. 
 
 Treatment. Careful attention to local and con- 
 stitutional symptoms. Atropin instillations, cold 
 compresses medicated with bichlorid of mercury 
 1-2,000, blood-letting from the temple, enucleation, 
 if there is not much hope of saving the eye by rea- 
 son of pain (glaucoma), pus in the anterior cham- 
 ber, and orbital cellulitis or cerebral meningitis 
 threatening. 
 
 Rupture of the Choroid. This usually takes 
 place as a result of a blow on the eye and is recog- 
 nized by a tear or rent in the choroid, resembling 
 in shape a new moon; the hollow or concavity of 
 the crescent with irregularly pigmented edges is 
 toward the disc, the crescent itself is yellowish- 
 white, this color resulting from a partial exposure 
 of the sclera. The common location of the rup- 
 ture is to the temporal side of the disc. If the 
 retina was not injured, or only partly so, at the 
 time the choroid was ruptured, some of the retinal 
 vessels may be seen passing over the crescent. At 
 the time of rupture or soon afterwards the rupture 
 may be covered with a hemorrhage, and hence 
 the picture just described cannot be definitely 
 studied with the ophthalmoscope until after ab- 
 
2/4 THE OPHTHALMOSCOPE. 
 
 sorption of the clot. The rupture may lie close to 
 or at some distance from, the disc, depending on the 
 character of the injury. The vision may be seri- 
 ously impaired if the rupture is at, or close to, the 
 macula. 
 
 Treatment. Cold compresses and a cycloplegic 
 if seen early. The injury is permanent and the 
 vision is disturbed accordingly. 
 
 Sarcoma of the Choroid. When seen with 
 the ophthalmoscope there is an elevation of the 
 retina and the growth beneath appears brownish 
 or black, or white in color ; it is a melino-sarcoma if 
 dark in color and a leuco-sarcoma if white. Melino- 
 sarcoma is much more common, the leuco-sarcoma 
 being very rare. This growth is usually situated to 
 the temporal side of the disc and may appear as far 
 forward as the ciliary body. The detached retina 
 if seen when the sarcoma is small, is applied equally 
 to the surface of the growth and does not tremble 
 or have the characteristic wave motion that is im- 
 parted to the retina when the eye is rotated and 
 there is fluid beneath the retina (see Detachment 
 of the Retina). Sarcoma of the choriod is a rare 
 disease, most unusual in children and usually oc- 
 curs in adults past forty years of age. 
 
 Symptoms. The patient notices a defect in 
 vision which the ophthalmoscope usually reveals 
 as detachment of the retina. This is one of the 
 first indications of the disease. As the sarcoma de- 
 velops there is an increase in the size of the detach- 
 
TUBERCULOSIS OF CHOROID. 275 
 
 ment and an increase in the tension together with 
 pain (glaucoma absolutum). The sarcoma may or 
 may not break through the sclera, but other organs 
 of the body, especially the liver, may suffer by 
 metastasis. 
 
 Prognosis. Most unfavorable. The eye must 
 be enucleated at once but this is no guarantee that 
 metastasis has not already taken place. 
 
 Treatment. Prompt enucleation and dividing 
 the nerve as far back as possible. If the orbital 
 tissue is involved this must be removed, including 
 the periosteum if necessary and following this later 
 with the employment of the X-rays. 
 
 Tuberculosis of the Choroid. This occurs either 
 as the disseminated (miliary) tubercle or as a soli- 
 tary (conglobate) tubercle. The former appears 
 as small round elevated spots of a pale red color 
 and grow rapidly. They appear in subjects who 
 have acute miliary tuberculosis, and are not often 
 seen in chronic tuberculosis. Solitary tubercle ap- 
 pears as a large mass which is virtually an accumu- 
 lation of many small nodules. This is a disease of 
 young subjects. The prognosis is very unfavor- 
 able for the eye and the patient. The treatment re- 
 solves itself into the systemic treatment of the pa- 
 tient and enucleation of the eye. 
 
 Glaucoma (yXavKo?, sea green). 
 
 A disease of the eye, so-called originally on 
 account of a greenish reflex occasionally ob- 
 
276 THE OPHTHALMOSCOPE. 
 
 tained from the pupillary area. A very bad 
 name, therefore, as it does not explain anything 
 about the disease, and in fact a greenish pupillary 
 reflex may be seen in certain conditions of the lens 
 and not necessarily in glaucomatous eyes. Glau- 
 coma, as now universally understood from one of 
 its chief signs, is a disease characterized by an in- 
 crease in the intra-ocular contents, and this is 
 spoken of and known as " tension." 
 
 Causes. The causes of increase in the intra- 
 ocular contents is either hypersection of the intra- 
 ocular fluids or a blocking or stoppage of the ex- 
 cretory passages, or both conditions together. Just 
 which of these causes precipitates the attack can- 
 not always be determined in each instance, but 
 there is hardly any doubt but that secretion is go- 
 ing on while the excretory passages are blocked, 
 and this explains many of the other symptoms of 
 the disease. 
 
 The lymph stream of the eye flows from the 
 vitreous through the zonula of Zinn into the pos- 
 terior chamber, through the pupil into the anterior 
 chamber, and hence into the angle of the anterior 
 chamber, into the canals of Fontana and the canal 
 of Schlemm, then into the lymph channels exter- 
 nally. Any obstruction to the onward flow of this 
 stream, means pressure of the intra-ocular contents 
 against the sensitive nerves and the rigid outer 
 tunic of the eye, with resulting symptoms. 
 
 Inspection shows the vessels of the ocular con- 
 
PLATE XII. 
 GLAUCOMA. FUNDUS OF LEFT EYE. DIRECT METHOD. 
 
 W. W. D. Aged 40 years. Salesman. 
 
 History. Vision of left eye was never as good as that ftf the 
 right. Has always worn glasses for " farsightedness." Never any 
 severe pain in left eye, and only lately has noticed that the vision 
 was getting much worse and the eye deviating outward. 
 
 Vision of left eye equals, seeing very large objects, or counting 
 fingers at about twelve inches distant. Eccentric fixation (periph- 
 eral vision). 
 
 Fundus Changes. Edge of disc seen with -f 6 D. and the bottom 
 of the cup is seen with a 5 D. Vessels of the retina disappear as 
 they pass into and around the edge of the disc, and are out of focus 
 when they reach the bottom of the cup, where they appear indis- 
 tinctly at the nasal side. The nerve is bluish or pearly white in 
 color and atrophic (glaucoma atrophy). The edges of the disc have 
 a distinctly yellowish color and the pigment is broken into fine par- 
 ticles. There is a peculiar redness showing at the macula. . 
 
 The cupping embraces the entire disc. 
 
 Right eye vision equals VI/VI with -|- 5 D. Glaucoma not 
 present. 
 
 278 
 
PLATE XII 
 
 Glaucoma 
 
SYMPTOMS. 28l 
 
 junctiva tortuous, appearing like fine corkscrews. 
 The cornea becomes cloudy, appearing like a piece 
 of glass that has been breathed upon, and is more or 
 less anesthetic. The anterior chamber is shallow, 
 the iris appearing nearer to the cornea than in 
 health. The pupil is dilated. The cornea being 
 cloudy and the large pupil being black the observer 
 may obtain at times and in certain lights a greenish 
 reflex from the pupillary area. 
 
 Subjective Symptoms. Pain in the eyeball 
 which may extend to the forehead, corresponding 
 to the eye involved, and also to the cheek bone and 
 same side of the nose, if the attack is unusually se- 
 vere. There is more or less dimness of vision de- 
 pending also upon the severity of the attack and 
 the dimness of vision may be particularly marked 
 in the nasal field. The patient notices halos (rings 
 of various colors) about any light. 
 
 Objective Symptoms. The tension of the eye- 
 ball is harder than normal. The beginner will ap- 
 preciate this by testing the tension of his own nor- 
 mal eye, by alternately pressing the ends of his 
 index fingers on his own eye through the upper lid 
 as the closed eye is directed downward, and then 
 testing the tension of the patient's eye in like man- 
 ner; or alternately testing the patient's eyes, as it 
 is not customary to find both eyes of the patient 
 exactly the same or equally affected, at the same 
 time. 
 
 Ophthalmoscopic Changes (Plate XII.). If 
 23 
 
282 THE OPHTHALMOSCOPE. 
 
 the media are not too cloudy the observer will see 
 
 1 i ) the disc excavated or cupped, this cupping ex- 
 tending to the edge of the disc and the edges being 
 quite abrupt or overhanging, and the disc edges sur- 
 rounded by a yellowish halo or glaucomatous ring; 
 
 (2) the vessels in the retina as they are traced to the 
 edge of the disc (cup) bend at right angles, and if 
 seen at the bottom of the cup, are crowded more or 
 less to the nasal side and are no longer in focus as 
 compared with the strength of lens required to see 
 the vessels as they appeared at the edge of the disc ; 
 
 (3) the arteries are seen to pulsate at the edge of 
 the cup. 
 
 Diagnosis. Hazy cornea; and also anesthesia 
 of the cornea ; this latter is proven by touching the 
 cornea with a small or narrow thread or piece of 
 cotton drawn to a fine point and made to touch the 
 cornea as the lids are kept wide open, the patient 
 not being conscious of the contact; anterior cham- 
 ber shallow ; pupil dilated 4 or 5 millimeters ; pain ; 
 increased tension ; cupping of the disc ; arterial pul- 
 sation ; halos and dimness of vision and diminution 
 of the field of vision; range of accommodation di- 
 minished. 
 
 Glaucoma seldom develops before the age of 
 twenty-five. Both eyes may be affected, but usu- 
 ally one is often affected long before its fellow. 
 Myopic eyes seldom develop glaucoma ; therefore it 
 is much more common in eyes that are hyper- 
 metropic. 
 
GLAUCOMA. 283 
 
 Varieties of Glaucoma. These are many. Pri- 
 mary and secondary; primary glaucoma develops 
 without any previous disease of the eye, whereas 
 secondary glaucoma develops as a consequence of 
 a previous disease (iritis, cyclitis, uveitis, injuries, 
 etc.). Primary glaucoma is recognized in three 
 forms: acute, inflammatory and chronic non- 
 inflammatory; this latter is also called simple 
 chronic glaucoma. The chronic inflammatory va- 
 riety is also called subacute or chronic congestive 
 glaucoma. 
 
 Differential Diagnosis Acute Inflammatory 
 Glaucoma, (i) Sudden onset; (2) intense pain; 
 (3) marked inflammation of eyeball; (4) in- 
 creased tension. May terminate ( i ) in total blind- 
 ness in a few hours (glaucoma fulminans or malig- 
 nant glaucoma). (2) After several attacks the 
 eyeball may remain stony hard and blindness re- 
 sult (stone blind) (glaucoma absolutum) ; or (3) 
 if inflammation persists the condition is one of 
 chronic inflammatory glaucoma. 
 
 Chronic Non-Inflammatory (Simple Chronic 
 Glaucoma) . This is the very opposite of the acute 
 inflammatory variety, as it is very insidious or slow 
 in its development, and patients occasionally verge 
 onto blindness before coming under observation. 
 This variety might be overlooked or mistaken for 
 optic atrophy, if it were not for the cupping of the 
 disc. 
 
 Prognosis. The earlier the case comes under 
 
284 THE OPHTHALMOSCOPE. 
 
 observation and treatment, the better, and the more 
 favorable the prognosis, and, vice versa, the longer 
 the treatment is delayed the more unfavorable the 
 case becomes and blindness may result as also loss 
 of the eye. Acute and uncomplicated glaucoma 
 receiving prompt treatment gives a favorable prog- 
 nosis. Cases of chronic glaucoma do not offer a 
 very encouraging prognosis ; considerable degener- 
 ation has very likely taken place and the field of 
 vision has very likely been cut down and visual 
 acuity diminished. 
 
 Treatment. This resolves itself into the sur- 
 gical, local medication, and internal treatment. 
 The surgical treatment is that of iridectomy. The 
 local medication is by myotics, drugs which con- 
 tract the pupil and therefore, if possible, draw the 
 iris away from the angle of the anterior chamber, 
 whereas if left alone and a myotic is not used the 
 iris is likely to adhere and block the canals of 
 Fontana and Schlemm. Of the myotics, eserin 
 in the strength of J/ to 2 grains of the sulphate 
 to an ounce of water may be prescribed, and one 
 drop of this solution, dropped into the eye every 
 three or four hours until the tension is reduced, 
 and then to be instilled three times a day. Pilo- 
 carpin nitrate in similar strength or stronger 
 may be used in place of -the eserin. Knowing 
 the decided danger or tendency for glaucoma to 
 affect the fellow eye, it is good practice to use the 
 myotic in both eyes, but not quite so freely in the 
 
GLAUCOMA. 285 
 
 unaffected eye. It is also good practice to combine 
 an equal amount of cocain with the myotic, as the 
 myotic is thereby more readily absorbed. If the 
 pain is unusually severe and does not yield after a 
 few instillations of the myotic, it may be necessary 
 to apply hot fomentations (cloths wrung out of hot 
 water), to draw blood from the temple with the 
 natural or artificial leach, and also to give a hypo- 
 dermic of morphia. Internally the salicylate of 
 soda should be given in large doses frequently re- 
 peated. The bowels should be kept open. Gentle 
 massage of the eye through closed lids is good prac- 
 tice, as it often does good, but must not be severe or 
 persisted in if the pain is increased thereby. 
 Whether the local or internal treatment gives relief 
 or not it is wise to perform an iridectomy as soon 
 as possible. 
 
 Secondary Glaucoma. This variety of glau- 
 coma, as its name implies, is brought about by a 
 previous injury or disease, namely, iritis, cyclitis, 
 swollen or dislocated lens, etc. 
 
 Treatment. This is practically the same as for 
 primary glaucoma. The swollen or dislocated lens 
 should be removed if it is the cause of the glau- 
 coma. When the glaucoma is brought about by ad- 
 hesion of the iris to the lens capsule (iris bombe) 
 an iridectomy or iridotomy must be performed. 
 Eyes with absolute glaucoma require enucleation 
 for relief of the pain. 
 
INDEX. 
 
 Absolute scotoma, 147 
 
 Accommodation, 18, 22 
 
 Acuity of vision, 140, 141 
 
 Aerial image, 30, 32 
 
 Albinism, 106 
 
 Albino, 9, 106 
 
 Albuminuric retinitis, 193, 194, 
 
 195 (Plate IV.) 
 atypical forms, 196 
 of pregnancy, 196 (Plate V.) 
 Amaurotic cat's eye, 224 
 family idiocy, 227, 228 
 Amblyopia, toxic, 245, 246 
 Aneridia, 100 
 Anemia of retina, 162, 163 
 causes of, 167 
 treatment of, 167 
 Aneurism of retinal vessels, 153, 
 
 154 
 
 Angioid streaks, 228 
 Anomalies, congenital, 98, 99, 
 loo, 101, 102, 103, 104, 105, 106, 
 107 
 
 Anterior polar cataract, 102, 103 
 Apoplexy of the retina, 186, 187 
 
 (Plate III.) 
 cause of, 187 
 prognosis, 187 
 treatment, 187 
 Aqueous humor, 79, 131 
 
 oblique illumination, 37, 38, 
 
 39, 40, 41, 42 
 
 ophthalmoscopic examination 
 of, 13, 14, 26 
 
 287 
 
 Arcus senilis, 128 
 Argand burner, n 
 Argyll-Robertson pupil, 252 
 Arterial pulsation, 184, 282 
 Arterio-sclerosis, 151, 152 
 Artery, central, 113, 122 
 decrease in size of, 151 
 embolism of (Plate II.) 
 increase in size of, 150 
 persistent hyaloid, 105, 106 
 Ascending neuritis, 238, 239 
 Astigmatism, 74 
 
 compound hypermetropic, 75 
 compound myopic, 75 
 mixed, 76 
 
 simple hypermetropic, 75 
 simple myopic, 75 
 Atrophic cup, 233 
 Atrophy of the choroid, 261 
 of the disc, 162, 163, 238 
 of the optic nerve, 246, 247 
 (Plate IX.), 248 (Plate 
 X.), 252, 257, 258 
 cause of, 257 
 diagnosis of, 258 
 prognosis, 258 
 treatment, 258 
 primary, 255 
 retina of the, 271 
 secondary, 255 
 
 Atypical forms of albuminuric 
 retinitis, 196 
 
 Beam of light, 48 
 
288 
 
 INDEX. 
 
 Black appearance of the pupil, 9 
 Blindness, 160, 161 
 Blind spot, HI, 146 
 Blood-vessels, 121, 127 
 
 new formed, 152, 153 
 Bracket, 10, 11 
 Brain tumor, 195 
 Bright's disease, 193, 194 
 
 retinitis due to, 193, 194 
 Briicke's muscle, 90 
 
 Cataract, anterior polar, 102, 103 
 
 black, 134 
 
 choroidal, 102, 134 
 
 cortical, 102, 134 
 
 lamellar, 102, 103 
 
 Morgagnian, 134 
 
 nuclear, 133 
 
 posterior polar, 102, 103 
 
 pyramidal, 102 
 
 ripe, 102 
 
 secondary, 271 
 
 senile, 102, 134 
 
 traumatic, 134 
 Catoptrics, 49, 50 
 Central artery, embolism of, 164 
 (Plate II.) 
 
 thrombosis of, 164 
 Cherry red spot (Plate II.) 
 Chimney, cover, 10, u, 42 
 Choked disc, 235, 236, 237, 238, 
 
 239 
 
 Cholesterin crystals, 139 
 Choroid, 84, 126 
 
 anatomy of, 84, 85, 86 
 
 atrophy of, 261 
 
 changes in color, 259, 260 
 
 colloid disease of, 271, 272 
 
 coloboma of, 105 
 
 degeneration of, in myopia, 
 271 
 
 Choroid, diseases of (Chapter 
 
 X.) 
 
 hemorrhage in, 261 
 hyperemia of, 260 
 inflammatory products in, 
 
 200 
 
 pigmentation of, 126, 260 
 
 rupture of, 273, 274 
 
 suppurative, 272 
 
 sarcoma of, 274 
 
 tigree, 127 
 
 tubercle of, 275 
 Choroidal atrophy, 261 
 
 ring, 116, 117 
 
 vessels, 127 
 Choroiditis, 261 (Plate XL) 
 
 central, 262, 270 
 
 changes in lens and iris in, 
 
 271 
 
 in retina and disc, 271 
 in vitreous, 271 
 
 diffuse, 269, 270 
 
 disseminated, 262, 267 
 cause of, 268 
 prognosis of, 268, 269 
 treatment of, 269 
 
 exudative, 263 
 
 guttate, 262, 270 
 
 macular, 270 
 
 metastatic, 262 
 
 myopic, 262, 271 
 
 old, 262 
 
 plastic, 262 
 
 posterior, 262 
 
 purulent, 262, 272, 273 
 
 recent, 262 
 
 senile, 262, 270 
 
 syphilitic, 262 
 
 varieties of, 262 
 
 with descemetitis, 272 
 Choroido-retinitis (Plate XI.) 
 Cicatricial bands in retina, 153 
 
INDEX. 
 
 289 
 
 Ciliary body, 89, 90 
 
 Cilioretinal vessels, 124 
 
 Circinate retinitis, 226, 227 
 
 Cloquet's canal, 106 
 
 Cocain, 16, 17 
 
 Colloid disease of the choroid, 
 
 271, 272 
 
 Coloboma of the choroid, 105 
 of disc, 105 
 of iris, 100 
 of lens, 105 
 
 Color of disc, 112, 121, 229, 230 
 Color of fundus, 108, 109, 125 
 
 affected by light em- 
 ployed, 109 
 in dark eyes, 109 
 in fair eyes, 109 
 in mulatto, 109 
 of various areas, 109, no 
 Compound astigmatism, 75 
 
 lens, 70 
 
 Concave mirror, 52, 53, 54 
 Condensing lens, 30. 31, 32, 33 
 Congenital anomalies, 99, 100, 
 101, 102, 103, 104, 105, 106, 107 
 Conjugate foci, 53, 63, 64 
 Connective tissue on disc, 107 
 Corectopia, 101 
 Cornea, 81, 82, 83 
 
 anatomy of, 81, 82, 83, 84 
 oblique examination of, 37, 
 
 38, 39, 40, 41. 42 
 ophthalmoscopic examination 
 
 of, 13, 14, 26 
 
 smoky appearance of, 128 
 reflex, 126 
 
 Cover chimney, 10, n, 42 
 Crescent, 116 
 
 myopic, 116, 118. 271 
 Cribrosa. lamina, 115 
 Cup, atrophic, 233 
 glaucoma. 233 
 24 
 
 Cup, physiologic, 113, 114, 233 
 to estimate depth of, 114, 
 
 US, 267 
 Cupping, diagnosis of normal and 
 
 abnormal, 114, 115, 234, 235 
 Cycloplegic, 15, 16, 17, 18 
 Cylinders, 68, 69, 70 
 Cysticercus, 139 
 
 D 
 
 Dark-room, 9, TO 
 
 Davis, Dr. E. P., 198 
 
 Descemetitis, 128 
 
 de Schweinitz, Dr. G. E., 216 
 
 Detachment of the retina, 219, 
 220, 221 
 
 De Zeng patent, 6, 7, 8 
 
 Diabetic retinitis, 206 (Plate VI.) 
 course, 206 
 prognosis, 206 
 treatment, 211 
 
 Diopters, 67, 68 
 
 Direct method, at a short dis- 
 tance, 13, 14, 26 
 close to patient. 23 
 enlargement of image, 27 
 estimation of refraction, 72, 
 
 73, 74, 75, 76 
 examination by, 13, 14, 26 
 schematic eye. 15 
 Disc, 33, 1 10. HI (Chapter IX.) 
 Diseases of the choroid (Chap- 
 ter X.) 
 of the optic nerve (Chapter 
 
 IX.) 
 
 of the retina (Chapter VIII.) 
 of the retinal vessels (Chap- 
 ter VII.) 
 of the vitreous (Chapter 
 
 V.) 
 
 Dislocation of the lens, 102, Fig. 
 63. 135 
 
290 
 
 INDEX. 
 
 Disseminated choroiditis, 262 
 Distortion of objects, 177 
 Dots, 185 
 
 Crick's, 185 
 
 Gunn's, 185 
 
 Mooren's, 185 
 
 Nettleship's, 185 
 
 neuritic, 197 
 
 Tay's, 270 
 
 E 
 
 Edema of the retina, 180 
 Electric flash, 160, 161 
 
 retinal changes from, 160. 
 
 161 
 
 Electric light, u, 12, 160, 161 
 Embolism of central artery, 164 
 (Plate II.), 167, 
 168, 169 
 causes of, 169 
 diagnosis of, 169 
 prognosis, 170 
 treatment of, 170 
 Emmetropia, 71, 72, 73 
 Entozoa, 131 
 Euthalmin, 17 
 Eserin, 17 
 
 Examination, methods of, 13, 14, 
 
 23, 26, 29, 30, 31, 32, 33, 34 
 
 by focal illumination, 37, 38, 
 
 39, 40, 41, 42 
 direct at short distance, 13. 
 
 14, 26 
 
 close to patient, 23 
 indirect, 29, 30, 31, 32, 33, 34 
 Excavated disc, estimating ex- 
 tent of, 114, 115 
 Exudative choroiditis, 262 
 atrophic stage, 261 
 exudative stage, 262 
 Eye (Fig. 61) 
 
 anatomy of (Chapter III.) 
 
 Eye, astigmatic, 74 
 
 emmetropic, 71, 72, 73 
 hypermetropic, 65, 70, 71 
 myopic, 64, 71, 72 
 schematic, 14, 15, 20 
 
 F 
 
 Field, 142 
 
 of vision, 143 
 
 field chart, 144 
 
 Fixed opacity, 128, 129 
 
 determining position of 
 
 130, 131 
 
 Floating opacity, 136 
 Focal illumination, 32, 37, 38, 39*, 
 
 40, 41 
 Focus, 48, 64 
 
 conjugate, 53, 63, 64 
 negative, 65 
 ordinary, 64, 65 
 real, 48, 49 
 virtual, 49 
 Foreign bodies in cornea, 128, 
 
 129 
 
 aqueous humor, 131 
 lens, 132, 133 
 vitreous, 136, 137 
 Fovea centralis, 97, 125 
 Fundus, 108 
 
 normal, 108, 109 
 color of, 108, 109, 125 
 in the albino, 109 
 in the blonde, 109 
 in the mulatto, 109 
 reflex, 26, 109, iio> ill 
 
 G 
 
 Gas, 10, ii 
 
 Glaucoma, 15. 16, Chapter X. 
 (Plate XIT.). 275. 276, 277 
 cause of, 276 
 
 cup, 232 (Plate XII.), 233. 
 234 
 
INDEX. 
 
 291 
 
 Glaucoma, treatment of, 284, 285 
 
 varieties of, 283 
 Glasses, correcting, 19 
 Glioma, of the retina, 224, 225, 
 226 
 
 pseudo, 226, 262 
 Gould, Dr. G. E., 141 
 Gunn's dots, 185 
 Guttate choroiditis, 270 
 
 H 
 
 Hansell, Dr. H. R, 233 
 Helmholtz's ophthalmoscope, I 
 Hemeralopia, 211 
 Hemorrhage, 154 
 
 causes of, 157 
 
 choroidal, 261 
 
 retinal, 154, 155, 156, 157, 186 
 
 subhyaloid, 157 
 
 vitreous, 157 
 
 Hemorrhagic retinitis, 187, 196 
 Hermance, Dr. W. O., 248 
 Homatropin, 18 
 Hulings-Jackson, 17 
 Hyaloid artery, 105, 106 
 Hyperemia of the choroid, 259, 
 260 
 
 of the optic disc, 237 
 
 of the retina, 158, 159 
 Hypermetropia, 27 
 
 tests for, 27 
 Hyphema, 131 
 Hypopion, 131 
 
 Indirect vision, 142, 143 
 Illumination, 10 
 
 candle, 10 
 
 daylight, 10 
 
 electric, ir, 12 
 
 focal, 37. 38, 39, 40, 41 
 
 gas, 10 
 
 Illumination, oblique, 37, 38, 39, 
 
 40, 41, 42 
 
 oil, 10 
 
 Welsbach, u 
 Image, aerial, 30, 32 
 
 formed by concave mir- 
 ror, 54, 55, 56 
 convex mirror, 56, 
 
 57 
 of eye ground, 27, 28, 
 
 36, 37 
 
 formation of, 32, 66 
 inverted, 30, 32 
 size of, 27, 28 
 upright, 23, 26, 66 
 virtual, 23, 26, 66 
 Indirect method, 29, 30, 31, 32, 
 
 33, 34 
 examination by, 29, 30, 
 
 31, 32, 33, 34 
 refraction by, 35, 36 
 value of, 34, 35, 36 
 Intense light, effect of (Sec 
 Electric and Snow Blindness), 
 160, 161 
 
 Intensity of light, 44, 45 
 Interstitial keratitis, 131 
 Intra-ocular optic neuritis, 239, 
 
 240 
 
 Irideremia, 100 
 Irido-choroiditis, 272 
 Irido-donesis, 135 
 Iris, 86, 99, 100 
 
 anomalies, 100, 101, 102 
 anatomy of, 86, 87, 88, 89 
 changes in, 132 
 congenital coloboma, 100 
 examination of, 131, 132 
 
 Iris diaphragm chimney, 10, II 
 reaction, 132 
 
292 
 
 INDEX. 
 
 Jennings, Dr. J. E., 102, 138 
 
 K 
 
 Keratitis, interstitial, 131 
 punctata, 131 
 
 Lamellar cataract, 102, 103 
 
 Lamina cribrosa, 96 
 vitrea, 85 
 
 Lamp, electric, 6, 7 
 oil, 10 
 
 Lens, 59 
 
 convex, 59, 60, 62, 63 
 concave, 60, 61, 62, 63 
 coloboma of, 105 
 combinations, 4, 5 
 condensing, 30, 31, 32, 33 
 crystalline, 92, 93, 94 
 cylinder, 68, 69, 70 
 dislocation of, 102, 135 
 foreign bodies in, 132, 133 
 numeration of, 67, 68 
 oblique illumination with, 
 
 38, 39 
 ophthalmoscopic examination 
 
 of, 132 
 
 smoky appearance of, 132 
 varieties of, 59, 60, 61, 62 
 
 Lenticonus, 104 
 
 Lenticular opacities, 102 
 color of, 102 
 position of, 102 
 
 Leucoma, 129 
 
 Leukemic retinitis, 188, 189 
 
 Leucosarcoma, 274 
 
 Light, 10, ii, 12, 44 
 streak, 122 
 
 Locomotor ataxia, 257 
 
 Loring, 2, 3, 4 
 
 Loring's ophthalmoscope, 2, 3, 4 
 
 Loupe, 40, 41 
 
 Luminous ophthalmoscope, 6, 7 
 
 M 
 
 Macula, 22, 97, 129 
 
 appearance of, 97, 125, 126 
 
 circulation at, 97, 98 
 
 coloboma of, 105 
 
 lutea, 97, 125 
 
 reflexes, 125 
 
 region, 97, 126 
 
 symmetric changes in in- 
 fancy, 227 
 
 vessels, 97, 98 
 
 Magnification by direct method, 
 27 
 
 by indirect method, 37 
 Magnifying glass, 31 
 Mariotte's blind spot, 46 
 Margin of the disc, no 
 Media, 27 
 
 of the eye, 27 
 
 examination of, 27 
 Medullary sheaths, 106, 107 
 
 (Plate IX.) 
 Medusa, 240 
 Melanosarcoma, 274 
 Membrana cribrosa, 115 
 Membrane, pupillary, 101, 102 
 Metamorphopsia, 177 
 Metastatic choroiditis, 262 
 Micropsia, 177 
 Microphthalmos, 99 
 Miliary tuberculosis, 275 
 Mirror, 2 
 
 concave, 2, 12, 13 
 
 reflection from, 52, 53, 54 
 
 convex, 56 
 
 movement of, 13, 14 
 
 perforation in, 2 
 
 plane, 6, 12 
 
 reflection from, 2, 8, 12 
 
INDEX. 
 
 293 
 
 Mirror, retinoscopic, 76 
 
 sight-hole in, 2, 6 
 
 stationary, 8 
 
 tilting, 2, 7, 8 
 Mixed astigmatism, 76 
 Morton's ophthalmoscope, 2, 5 
 Muller's fibers, go 
 Musser, Dr. J. H., 248 
 Mydriatics, 15, 16, 17, 18 
 
 objections to, 15, 16, 17, 18 
 
 uses of, 15, 16 
 Myopia, 29 
 
 description of, 64, 71, 72 
 
 test for, 71, 72 
 Myopic choroiditis, 271 
 
 crescent, 271 
 
 degeneration of the choroid, 
 271 
 
 N 
 
 Nebula, 129 
 
 Negative focus, 65 
 
 Nerve, optic, 95, 96 
 -fibers, 95, 96 
 -head, 96, 97, 100, m 
 diseases of (Chapter IX.) 
 
 Nettleship's dots, 185 
 
 Neuro-retinitis, 243, 244, 245 
 
 Neuritis, optic, 239 
 
 interstitial, 244, 245 
 retrobulbar, 239, 244, 245 
 
 New vessels in vitreous, 153 
 
 Nicotin, chronic poisoning, 245 
 
 Night-blindness, 211 
 
 Normal eye, 71, 72, 73 
 cupping, 113, 114 
 fundus. See Chapter IV. 
 
 Nubecula, 129 
 
 Nystagmus, 106 
 
 Object lens, 30, 31, 32, 33 
 handle for, 31 
 
 Oblique illumination, 37, 38, 39, 
 
 40, 41, 42 
 examination by, 37, 38, 39, 
 
 40, 41, 42 
 
 Observer, 18, 19, 20, 21 
 Opacities, cholesterin crystals, 
 
 139 
 
 corneal, 128, 129, 130, 138 
 fixed, 139 
 floating, 139 
 hemorrhages, 157 
 in aqueous, 138 
 lenticular, 138 
 locating the position of, 138, 
 
 139 
 
 vitreous, 137, 139 
 Opaque nerve-fibers, 106, 107 
 
 (Plate IX.) 
 Ophthalmoscope, I 
 choice of an, I 
 Helmholtz, I 
 how to use the, 9, 10, 23, 
 
 24, 25 
 
 Loring, 2, 3, 6 
 Morton, 2 
 selection of, I 
 Thorner, 8, 9 
 Ophthalmoscopic examination, 
 
 23 (Chapter I.) 
 direct method, 23, 26, 27, 28 
 indirect method, 26, 29, 30, 
 
 3i 
 
 Optic atrophy, primary, 246, 247 
 (Plates IX. and X.) 
 
 secondary, 255 
 
 simple, 255 
 Optic disc (disk), in, 112 
 
 atrophic cup, 233 
 
 atrophy of (Plate X.) 
 
 coloboma of, 105 
 
 color of, 112, 121, 229, 230 
 
 congenital crescent of, 116 
 
294 
 
 INDEX. 
 
 Optic disc, connective tissue on, 
 
 107, 112 
 cupping of, 231, 232, 233, 
 
 234, 235 
 
 detailed study of, 112 
 elevation of, 235, 236, 237 
 enlargement of, 237 
 excavation of in atrophy, 233 
 hyperemia of, 230 
 in glaucoma, 233, 234, 235 
 level of, 231, 232 
 margin of, 112 
 myopic crescent of, 116, 118, 
 
 271 
 nerve fibers, 106, 107 (Plate 
 
 IX.) 
 
 physiologic cup, 113, 114 
 pigment on, 112 
 pillar of, 230, 231 ' 
 shape of, 112, 113 
 situation of, 112 
 size of, in 
 swelling, estimating extent 
 
 of, 237 
 Optic nerve, atrophy of (Plate 
 
 X.) 
 
 diseases of (Chapter IX.) 
 head of, in 
 
 Optic neuritis, 17, 18, 235 
 retrobulbar, 244, 245 
 
 Panophthalmitis, 272, 273 
 
 cause of, 272, 273 
 
 prognosis of, 273 
 
 treatment of, 273 
 Papilla, in, 112 
 Papillitis, 235, 236, 237, 238, 239 
 
 cause of, 241, 242, 243 
 
 prognosis, 2Ai 
 
 treatment, 243 
 Papillomacular fibers, 245 
 
 Papillo-retinitis, 193, 194, 238 
 Parallactic movement (Chapter 
 
 IV.) 
 
 Parallax (Chapter IV.), 115 
 Pencil, 48 
 
 Perforation, central in mirror, 2 
 Perimetry, 140, 142, 143, 144, 145, 
 
 146 
 
 Perivasculits, 152 
 Pernicious anemia, 167 
 Persistent hyaloid artery, 105. 
 
 106 
 
 Phthisis bulbi, 273 
 Physiologic cup, 113, 114 (Chap- 
 ter IV.) 232, 233 
 estimation of depth of, 114, 
 
 115 
 
 to distinguish from patho- 
 logic cup, 233 
 Pigment on disc, 120, 121 
 ring, 1 20, 121 
 streaks in retina, 228 
 Pigmentary degeneration of 
 
 retina, 211 
 
 unusual form (Plate VII.) 
 Pigmentation of the choroid, 126, 
 
 260 
 Pigmentosa, retinitis, 211, 212 
 
 (Plate VII.) 
 Plane mirror, 12 
 
 reflection from, 51, 52 
 Porus opticus, 113 
 Position of light, 21, 22 
 of observer, 20, 21, 22 
 of patient, 22, 23 
 Posterior polar cataract, 102, 103 
 staphyloma, 267 
 synechia, 131 
 Postpapillitic atrophy (Plate 
 
 IX.) 
 
 Primary atrophy of the optic 
 nerve (Plate X.) 
 
INDEX. 
 
 295 
 
 Prisms, 58, 59 
 Proliferating retinitis, 153 
 Pseudo-glioma, 226 
 Pulsation, arterial, 154 
 
 venous, 123, 124, 154 (Chap- 
 ter IV.) 
 Punctate condition of the fun- 
 
 dus, 184, 185 
 
 Pupil, black appearance of, 9 
 congenital anomaly, 100, 101. 
 
 102 
 in atrophy of optic nerve, 
 
 252 
 
 reflex from, 9 
 
 Papillary membrane, 101, 102 
 Purulent choroiditis, 262 
 
 R 
 
 Randall, Dr. B. A., 140 
 
 Ray, 45 
 
 Rays of light, 12 
 
 convergent, 12, 47, 48 
 
 divergent, 12, 47 
 
 emergent, 45, 46 
 
 incident, 45 
 
 parallel, 12, 47 
 
 reflected, 12 
 Reflection, 12, 49, 50 
 
 laws of, 50 
 Reflex, corneal, 126 
 
 chcfroidal, 26 
 
 fundus, 26, 109 
 
 red, 26, 109 
 
 Weiss, 125 
 
 Refraction, 57, 58, 59, 60, 61, 62 
 Retina, 90, 124 
 
 anatomy of, 90, 91, 92 
 
 anemia of, 161 
 
 atrophy of, 271 
 
 changes in vascularity of, 
 157, 158 
 
 commotio, 224 
 
 Retina, detachment of (Plate 
 VIII.), 219, 220, 221 
 causes of, 221 
 diagnosis, 219, 220, 221, 
 
 222 
 
 prognosis, 223 
 treatment, 223, 224 
 
 diseases of (Chapter VIII.) 
 
 edema of, 180 
 
 exudation into, 181 
 
 glioma of, 224, 225, 226 
 diagnosis of, 226 
 prognosis of, 226 
 treatment, 226 
 
 hemorrhages into, 154, 155, 
 156, 157, 158, 186 
 
 hyperemia of, 158, 159, 160 
 
 inflammation of, 176, 177 
 
 irritation of, 160, 161 
 
 opacities of, 178, 179, 180, 
 181 
 
 pigment streaks in, 228 
 
 pigmentary degeneration of, 
 214 
 
 pigmentation of, 158 
 
 rupture of, 224 
 
 sclerosis of, 214 
 
 shot or watered silk appear- 
 ance of, 125 
 
 transparency of, 125 
 
 vessels of, 125 
 Retinal atrophy, 271 
 
 capillaries of, 123, 124 
 
 changes due to intense light, 
 160, 161 
 
 circulation of, 125 
 
 reflex, 109, 125 
 
 veins, thrombosis of, 170, 171 
 
 vessels, 123, 124, 125, 148, 
 149, 150, 151, 152, 153, 
 
 154 
 diameter of, 149, 150 
 
296 
 
 INDEX. 
 
 Retinal vessels, diseases of, 149, 
 150, 151 
 
 distribution of, 121, 122, 
 123, 124 
 
 light streak of, 122 
 
 pulsation of, 123, 124 
 
 relative size of arteries, 
 and veins, 148 
 
 sclerosis of, 149, 150, 151 
 
 tortuosity of (See 
 Thrombosis) 
 
 walls of, 151 
 Retinitis, 176, 177 
 
 albuminuric, 193, 194, 195 
 causes of, 178 
 centralis et striata, 228 
 circinata, 226, 227 
 circumscribed, 184 
 diagnosis of, 177 
 prognosis of, 177, 178 
 treatment, 178 
 
 (Plate IV.) 
 
 varieties of, 196 
 degenerative, 196 
 diabetica, 206 
 diffuse, 182, 183 
 electric, 160, 161 
 hemorrhagic, 187, 196 
 
 causes, 187 
 
 prognosis, 187 
 
 treatment, 188 
 leukemic, 188, 189 
 neuro-, 196 
 
 of pregnancy (Plate V.), 196 
 pigmentosa, 2ii (Plate VII.) 
 
 diagnosis of, 214 
 
 treatment of, 214 
 proliferans, 153 
 punctata, 184, 185 
 purulent, 228 
 secondary, 187, 196 
 serous, 182, 183 
 
 Retinitis, simple, 182, 183 
 
 solar, 160, 161 
 
 splenic, 188, 189 
 treatment, 193 
 
 syphilitic, 188 
 
 treatment, 188 
 
 varieties of (Chapter VII.) 
 Retinochoroiditis (Plate XI.) 
 Retinoscopy, 76, 77, 78 
 
 in astigmatism, 77 
 
 in hypermetropia, 77 
 
 in myopia, 77 
 
 methods of examination, 76 
 
 77 
 
 mirror, 76 
 principle of, 76 
 Retrobulbar neuritis, 244 
 acute, 244, 245 
 cause, 245 
 prognosis, 245 
 treatment, 245 
 chronic, 244, 245 
 cause, 245, 246 
 prognosis, 246 
 treatment, 246 
 Ring, choroidal, 116, 117 
 pigment, 116, 117 
 scleral, 116 
 Room, 9, 10 
 Rupture of the choroid, 273, 27^ 
 
 Sarcoma, of the choroid, 274 
 
 stages of, 275 
 Schematic eye, Thorington's, 14 
 
 15 
 
 Scleral ring, 116 
 Sclerophthalmia, 99 
 Sclerosis of the vessel walls 
 
 151, 152 
 
 Sclera, 79, 80, 81 
 Sclerotic, 79 
 
INDEX. 
 
 297 
 
 Scleral ring, 115, 116 
 
 Scotoma, 146, 147 
 
 Secondary atrophy of the optic 
 
 nerve, 255 
 Selection of an ophthalmoscope, 
 
 i 
 Senile cataract, 102, 134 
 
 changes in the blood-vessels, 
 
 iSi, J 52 
 
 choroiditis, 270 
 
 guttate choroiditis, 270 
 Serous retinitis, 182, 183 
 Shadow-test, 76, 77, 78 
 Sight-hole, 2 
 
 Simple hypermetropic astigma- 
 tism, 75 
 
 myopic astigmatism, 75 
 Snow blindness, 160, 161 
 Sparkling synchysis, 139 
 Spheres, 59, 60, 61, 62, 63 
 Spherocylinders, 70 
 Spiller, Dr. Wm. G., 248 
 Squint, 22 
 
 Staphyloma posticum, 267 
 Subhyaloid hemorrhage, 157 
 Subretinal cysticercus, 139 
 Sweet, Dr. W. M., 233 
 Symmetric coloboma of the 
 lenses, 105 
 
 dislocation of the lenses, 105 
 Synechia, anterior, 131 
 
 posterior, 131 
 Synchysis scintillans, 139 
 Syphilitic choroido-retinitis 
 (Plate XI.) 
 
 retinitis, 188 
 
 Tay, 227 
 
 Test cards, 140, 141, 142 
 Thrombosis of the central artery, 
 164 
 
 Thrombosis, of retinal vein, 170, 
 
 171 (Plate III.) 
 causes of, 175 
 diagnosis, 174, 175 
 treatment, 175 
 Tiger-skin fundus, 127 
 Tilting mirror, 2 
 Tobacco amblyopia, 245, 246 
 Tortuosity of retinal vessels, 170, 
 
 171 
 
 Toxic amblyopia, 245, 246 
 Tubercle of the choroid, 275 
 Tumor, brain, 242 
 Tumors, intraocular, 274 
 
 u 
 
 Uvea, oo 
 Uveal tract, 90 
 
 V 
 
 Vein, central, 122 
 
 decrease in size of, 150 
 
 increase in size of, 149, 150 
 Veins, thrombosis, 170 
 
 vorticose, 86 
 
 Venous pulsation, 123, 124 
 Vessel walls, sclerosis of, 151, 
 152 
 
 choroidal, 127 
 
 cilioretinal, 124 
 
 diseases of, 151, 152 
 
 new-formed in retina, 152 
 in vitreous, 153 
 on disc, 122 
 
 retinal, 121, 122, 123, 124 
 
 size of, 28, 122 
 Vision, 140, 141, 142 
 
 central, 141, 142 
 
 peripheral, 142, 143, 144, 145, 
 
 146 
 
 Visual acuity (Chapter VI.) 
 Vitreous, 94, 95, 136, 137 
 
298 
 
 INDEX. 
 
 Vitreous, anatomy of, 94, 95 
 changes in choroiditis, 271 
 cholesterin crystals in, 139 
 diffuse opacity in, 272 
 foreign substances in, 139 
 hemorrhage into, 136 
 movable opacity in, 137, 138 
 new vessels in, 153 
 oblique illumination of, 137 
 opacities, 136 
 
 ophthalmoscopic examina- 
 tion of, 136, 137 
 purulent exudations in, 272 
 
 Vorticose veins, 86 
 
 w 
 
 Walls of retinal vessels, 151 
 
 white lines along, 152 
 Weeks, Dr. John E., 241 
 Weiss reflex, 125 
 Welsbach, u 
 Wickerkiewicz, 101 
 
 Yellow, reflex of purulent cho- 
 roiditis, 272 
 spot, 125 
 
 position of, 126 
 
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