r^^>.»^tek Pages I. Ophtlialnioscopy l-'24 II. Diseases of the Retina ^25-3H III. Diseases of the Choroid 89-56 IV. Diseases of the Optic Nerve .57-73 V. Field of Vision: Indirect and Direct Ophthalmoscopy 74-96 VI. Systematic Examination of Eye 97-109 VII. (ilaucoma 1 lO-llo \'I1I. Optical Principles, Test Type, Lenses, Refraction, and Cycloplegics 116-1,")9 IX. Applied Refraction, Astigmatism, Pres- byopia 160-184 X. Heterophoria — Muscular Insufficiency... 185-187 XI. Retinoscopy 188-^208 XII. Measurement of Lenses, Prescription writing. Transposition, and Frame Fit- ting ^209 ^218 Index 219-223 COLORED PLATES Pi.ATK Deschiptiox 1*.\(;k I. Dark Xonnal Fundus IS 11. Liuht Xonnal P\in(lus -2(1 III. Myopic Crescent -2^2 IV. Detachment of the Retina -2(1 V. Retinitis Pi<>inentosa 80 VI. Retinitis Pigmentosa with oblong (Hsc iVl VII. Embolism Central Retinal Artery 84 VIII. Retinitis Albuniinurica 86 IX. Coloi)oma of the Choroid 40 X. Sarcoma of the Choroid 4*2 XI. Posterior Staj)hyloma with Choroiditis 44 XII. Disseminated Choroiditis 4(1 XIII. Rui)ture of the dioroid 48 XIV. Central Choroiditis .50 XV. (Vntral dioroiditis (Slight) .n XVI. Injury 54 XVII. Cflaucoma with Atr()i)hy .58 XVIII. Optic Atroi)hy 00 XIX. ()i)a(|ue Xerve Fibres ({"2 XX. Plain dioked Disc (>4 XXI. Xeuroretinitis ()(i XXII. Papillitis Ilaeniorrhagica ()8 XXIII. (ilauconia 70 XXIV. Haeniorrliagic (Tlauroma 7-2 X. B.— A duplicate set of Plates for use with the Sche- matic Eve is inserted. OPHTHALMOSCOPY RETINOSCOPY and REFRACTION CHAP'] KR I Ophthai.moscopy A complete examination of the eye cannot be made withont a working' knowle{l<^'e of tlie opli- thalmoscope; and diseases of the retina, choroid, and optic nerve cannot be nnderstood nnless the examiner is master of tliis inex])ensive little in- strnment. The author believes he has made the subject simple, interesting, and within easy reach of any physician or medical student. The student is urged to follow closely the method of instruc- tion, since he will be expected to make a good ()j)hthalmoscopic examination of his first ])atient. If the student is expected to see the details of the fundi of the first ])atient examined, he must be taught the first ])rinciples of ()])hthalm()sco])y on models. Medical men are usually deficient in their (i])lithalm()sc()])ic studies and it is a hard task to insti'uct them upon li\iug sub/jects. W^ith the method no\\ to be described, the student is taught the use of the ophthalmoseopr in a sur- prisingly sliort time. 2 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Ophthalmoscopy is usually taught to luider- graduates ujDon the living subject in small classes ; but it is difficult to get enough instructors, who can teach, to carry on the work successfully in this manner; and it is practicall}^ impossible to get the variety of cases necessary for instruction at any specified time even in very large clinics. The author will place in the hands of his readers, a method of study whereby practically all diseases of the interior of the eye are observed in a model ; and, when these have been mastered, the student will be as well prepared to examine the interior of any patient's eye and study the picture as he would that of any external disease, because they are just as easily recognized. jNIedical men as a rule do not profess to know much about the use of the ophthalmoscope; and the majority of them believe it is practically im- possible for them to learn its use within a reasonable time. This idea must be abandoned before any progress can be made. ]Many medical men believe that lesions found in the interior of the eye Avhich would come under their observation would be difficult to detect ; but this also is not true. ]Many lesions found in diseases of the retina, choroid, and optic nerve are usually so pronounced in ty])e that a diag- nosis can be made on sight. It is the object of this chapter to sliow liow they can easily be made visible. Before beginning the subject of ophthalmo- scopy, a description of the ophthalmoscope will be given: and, after that, the student will be Ol'HTFIALMOSCOPY Fig. 1 Electrical Ophthalmoscope. P%. 2. Lorintr Ophthalmoscope. expected to uiulerstaiul the siil)ject as he pro- gresses, and not pass anything until lie is master of it. The OiMrniAi..Ai()sc()PK: In the diagnosis of many diseases, including some conditions in the domain of ge?iera] medicine, which ])ro(luce char- acteristic clianges in the interior of the eye, tlie use of the ophthalmoscope, which is an instru- ment designed for the illumination of its trans- parent media and deeper structures making their examination as sim])le and easy as that of the external ])ortion, is indispensable. I OPHTHALMOSCOPY. RETINOSCOPY AND REFRACTION There are many models of the instrument, but any one whicli the doctor accustoms himself to is usually satisfactory. Electrical Ophthalmoscope: It is easier for a beginner to ilhuninate the interior of the eye with an electrical ophtlialmoscope, ( Figure 1 ) which while expensive, offers some advantages. The instrument most generally adopted in the United States of America is the Loring ( Figure 2) ; and, in tliis work, it will l)e described and directions given foi* its use in the practice with the model. LoRiXG Oph'J'halmoscope: The essential parts of a Loring ()])hthalmoscope are a per- forated mirror for reflecting the light into the eye and two discs carrying convex ( -p) and con- cave ( — ) lenses. The larger inner disc contains seven convex lenses, varying by diff'erences of 1 dio])tre (abbre- ^iated D) from 1 to 7 dioptres, and eight concave ones varying similarly from 1 to 8 diop- tres. Between the plus and minus 1 D. lenses in this disc is left an opening of corresponding size which contains no lens and is s])oken of as the aperture. Witli these may be combined the lenses in the small outer disc wliich contains one each of H- 0..50 D. and + 16 D.. as Avell as — 0.50 D. and — 16 D. lenses. By combining the outer and inner discs, one is able to get any con- vex or concave lens from 0..50 to 24 D. The unit of lens measure, the dioptre, men- tioned above and frequently used throughout the text, has liv international am-eement been ac- OPHTHALMOSCOPY D cepted as the strength of that lens whieh has its focus at a (hstance of one metre (40 inches). With the dioptric strength of a lens known, its focal length is ascertained hy (hvision into 100 centimeters or 4-0 inches, and conversely the (hoptric measurement is arrived at l)y division of the focal (hstance into these same figures. Thus a lens of 2 1). has a focal length of .30 centimeters, or 20 inches; and one of 2.5 centi- meters or 10 inch focal length is sj)oken of as a 4 1). lens eithei* plus or minus, as the case may he. The fundus of a normal eye can he seen through the aperture without any lens; hut, if the eye examined is hypermetropic (far sighted), plus lenses are required; if myopic (near sighted) minus lenses are necessary to secure a correct view of it. It is not necessary to have absolute darkness for ophthalmoscopy, but the darker the examin- ing room, the better the illumination of the fundus and consequent ease of examination and accuracy of findings. In the sick room, drawing the shades will sufHce; hut in the office, the walls and ceilings may well be ])ainted black. Direct ^iF/riioi): To examine an eye witli the ophthalmoscope by direct method, the ex- aminer should be as near it as possible, keep both eyes open, and look into the distance with the examining eye through the a])erature of the in- strument, l^y doing so, he will learn to relax his own accommodation. Light: The interior of the eye must be illu- minated and students find it difficult at first to OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 3. Spool reflect and keep the light directed into the eye while making an examination. By practice, how- ever, this can he learned upon the model as readily as one can hy practice learn to shoot pigeons thrown from a trap. Illumination : The simplest inexpensive method of mastering control of the illumination for the application of ophthalmoscopy is to prac- tice reflecting the light from the ophthalmoscope into an ordinary spool ( Figure 3 ) with the end toward the operator open and the other closed with white paper upon the inside of whicli have heen placed hlack or red markings that can be identified by tlie student as he looks through the aperture of the instrument. After the student has learned to control the reflected liglit and is able to see through the perforation in the mirror, it is not difficult to illuminate the interior of the eye. The colored pictures that follow can be studied in the book and a working knowledge obtained, but a much better method is to studv OPHTHALMOSCOPY Fig. 4. Author's Practical Schematic Eye the pictures in a special adopted model for the purpose. A Practical SchemxVtic Eye: (Fig. 4) can be made by any carpenter in the following manner. Select a piece of wood, round or square, 3I/8 inches long and 21/1^ inches in diameter: bore a hole 1-^4 inclies in diameter through it, and saw a slit through the barrel near one end to insert the picture, and anotlier slit at the ()])])osite end, large enough to insert a phis 18.00 1). lens from the opthahiioscopic case. The two slits should be two inches a])art in order to a])proxi- mate a normal eye. Two tacks, (one on eitlier side) are driven into tlie front end with the heads ])roiecting far enougli to liold tlic lenses from the trial case, to be used for retinoscopy. Degrees 6 OPPITHALMOSCOPY, RETINOSCOPY AND REFRACTION denoting tlie axis of the cylinder can be marked on the model as they are made on any trial frame. A stand can be made by making a base and an upriglit and joining the ])ase with the model, in- sei'ting one end in a hole made in the barrel, the other in the base. The model can be ])ainted as desired, but the inside of tlie barrel should ])e black; the stand should be made to give tlie model an incline of about 30 degrees. A picture is placed in the back of the barrel, and in front a plus 13 dioptre glass from the ophtlialmoscopic case. In front of this lens is ])asted a piece of black paper or cardboard witli a 1.5 millimeter opening in the center to represent the pupil. When proficiency is obtained witli the large pupil, another paper is pasted over tlie first one with a 10 millimeter opening and wlieii tlie picture is easily seen, another pa])er can be pasted over the last one with a .5 millimeter open- ing in the center of it. The pictures in the back of the model can be studied with the ophthalmo- scope, using any desired pupil until proficiency is obtained. To make ophthalmoscopy simple, easy, and interesting, one should master the model before looking at the eye of a ])atient. Retinosco])y can be ])racticed upon the model with a 10 milli- meter pupil, various strength lenses being placed in front of the pupil. Du])licates of the 24 pic- tures are ])laced in tlie book to be cut out. mounted on cardboard, with projecting thumb piece for inserting: these are for use with the model. OPHTHALMOSCOPY Fig. Author's Schema; Eye. The author's Schematic eye (Fit^'ure .3) is a model designed to make the study of ophthahno- sco])y simple, easy and interesting. It consists of one cylindrical tuhe telesco])ing another one in such a manner that a long or short eye can he produced. If the t\\'() ])arrels arc ])us]ied to- gether as far as jjossihlc we have a hypermetro])ic. short, or far sighted eye. If the two harrels are pulled apart as t'ai' as possihle. we ])roduce a myopic, long, oi* near sighted eye. If half way. — normal. 10 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The model has a lens to represent the crystal- line lens of the human eye, and an iris diaphragm. This iris diaphragm which when fully dilated produces a pupil of 30 millimeters, is made to open and close at the will of the operator and can be made to represent a normal, contracted, or dilated pupil. The beginner can commence his study with the maximum pupil and gradually decrease the size until it is much smaller than the pupil of a normal eye. When the student has mastered control of the light and can examine the fundus of the schematic eye which is provided with twenty-four pictures, two normal and twenty-two abnormal ones, rep- resenting gross pathological lesions, he is ready to successfully examine the human eye. EXAMIXATIOX OF THE SCHEMATIC Eye: The direct examination of the schematic eye should be mastered before the student attempts the ex- amination of a patient. If this be done and well done, he should be able to make a good ophthal- mosco23ic examination on the first patient seen. To be a master of the schematic eye one should not onh^ be able to distinctly see the fundus, but to know what to look for and recognize it when found as well. In the study of the individual pictures, the student should bear in mind that no great attention should be given to the color of the background of the eye, as this differs in a hundred cases, as one hundred faces differ. The student should also understand that these twenty-four pictures were made to teach and impress the pathological lesions as well as the OPHTHALMOSCOPY 11 normal fuiuliis on his mind. All of them were made to first represent normal fundi and are as different in color as three colors can make possi- ble. After the twenty-four normal ])ictures were finished, twenty-two of them were made ])ath- ological hut the normal ])art of the ])ieture re- mains. Xerye Head: The nerve head should he noted, hut in actual ])ractice much stress should not he ])laced u|)on its color. It frequently has a ^vhite scleral and black choroidal rino^, which are normal and should be in the same plane as other parts of the fundus, not too high, "swollen nerve" or "choked disc" (Page Qo) nor pushed back "cupped" as in glaucoma (Page 71). XoR:\rAL Eyes: In normal eyes the vessels should emerge from the center of the nerve and not from the edge ( Page 19 ) . If they all emerge from the edge of the nerve, a picture of glaucoma is seen ( Page 71 ) . If some of the arteries emerge from the center of the nerve and some from the edge, there is a possibility of atro])hy and the field should be taken. The Retixa: The retina is transparent and we need to observe its vessels only. The arteries are smaller than the veins, which accompany the former rather closely, the ratio of size being as two is to three. These vessels have no regular course and slight deviations should not be noted. By referring to the twenty-four pictures which follow, it will be seen that in no two are the retinal vessels the same. Working Pean : Before beginning the study J 2 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION of the individual pictures a general working plan of using the ophthalmoscope should be adopted. The student must be able to determine whether an eye is hypermetro])ic or mj^opic before he can detect gross pathological lesions. Working with the schematic eye, one should measure refraction by the image of the screen — the stippling seen in the picture. When colored pictures are printed, a screen is used; and, when we magnify these pictures with the ophthalmo- scope, its image is easily seen. In fact one can- not help seeing it and this image is observed in the measurement of the refraction instead of the white lines on tlie arteries in the human eye. TWO RULES TO REMEMBER First — Hypermetropia: The strongest con- vex ( + ) lens with Avhich the screen can be seen at all represents the measure of the hyper- metropic, "far sighted" "short eye" produced when the barrels of the schematic eye are fully closed. Second — JNIyopia: In myopia "near sighted" or "long eye" is produced when the barrels of the model are separated beyond the point marked normal (the more the separation the higher de- gree of myopia) ; the weakest minus ( — ) lens with which the screen can be seen at all will be the measure of the myopia, short sighted, or long eye. When the student can readily measure the myopia or hypermetropia in the schematic eye, OPHTHALMOSCOl'^ 13 set at any one of the numerous ])ossible positions, he will i-eadily nieasui'e the ret'raetive error in the human eye. Position or 'ihk Kxaminkk and the Model: Tlie model should he plaeed on a table high enough to he on a level with the examinei-\ eye when sitting in an easy ])osition, in iVont of it. When using the right eye, sit in front of and to the right side of the model and ])laee the light to its right side. When using the left eye, sit in front of the model to the left and have the light on the left side of the model. These are the posi- tions one would assume if a ])atient was being examined. ( See Page 97. ) Source of I^i(;ht: The source of light may be either an oil lam]), gas, or electric light with a frosted globe, and should be on a level with the model. The h'ght should be ])laced upon a brac- ket that can be moved to either side of the model as the student works with his right or left eye, and which can be moved u]) or down in order to get the desired light. Size of Pimml ix the Schemaik- Kve: The pupil in the schematic eye can be made so wide that anx'one can see the ])icture in the back of the model the first time it is examined: the pu])il can be reduced gi-adually as ])r()ticiency is accjuired. Distance From the Model: Wh.en looking into a room through a key-hole, the closer the observer is to it the larger will be the field. The same is true in lookinu' into the model, or into 14 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION the eye; the closer the observer, the more he will see. Direct Exa3iixation : With the room suf- ficiently darkened, the source of light and the model properly arranged, begin the examination by assuming the first position for direct o])hthal- moscopy (Page 97), at a distance of about two feet ; and, with the mirror of the ophthalmoscope tilted towards the source of light, reflect it into the pupil of the model, which at first should be made as large as possible; when the red reflex is seen through the a])ertin*e of the instrument gradually approach it coming as close as possible and assume the second position for direct ophthal- moscopy. The same position should be observed as when examining a patient. (See Page 97.) What to Forget: To make ophthalmoscopy simple and easy, the observer must first know what constitutes the normal eye. Forget the general color of the picture examined because the fundi of no two eyes are alike. They are as different as the faces seen on a crowded street; they all have eyes, ears, nose and mouth, but these all go together to make the face. All fundi have a nerve head, and retinal vessels, but the color of the former varies so much that the observer should forget about its having a color as well as the color of the general back- ground of the eye because of its variations. Text books on ophthalmology usually devote so much space to describing the color of the back- ground of the eye that the student soon becomes OPHTHALMOSCOPY 15 confused. In this method, students are not ex- pected to know or remember anything about the color of the fundus. Things to Remember : The student must be able to measure the refraction of the eye before he can make progress in diagnosis. The observer always begins his direct ophthalmoscopic exam- ination with tile aperture, when he will be able to see the screen in normal and liypermetropic eyes. Screen: If the observer can see the screen with the aperture he will rotate convex ( + ) lenses in front of it by turning the wheel on the edge and will remember that tlie strongest convex lens with which he can see the screen ai all will represent the amount of hypermetropia. If he cannot see the screen with the aperture of the ophthalmosco])e he must turn on minus lenses to make it visible; the weakest minus glass with ^\ hich he can see the screen represents the myopia. Retinae Vessei-s : The student must remem- ber that the retinal veins are one third larger than the arteries and that tlie retinal vessels seem to come out of the center of the optic nerve and course across the fundus. Scleral and Choroidal Rixcjs: There may be a white scleral ring that the student can see around the edge of the nerve and a black choroi- dal ring on the outside of it. These two rings may vary or may not be visible and they some- times appear to encircle the nerve head or only part of it; but \}\ no case are they ])athological. 16 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Atkophu and Pigment Spots: If atrophic or pigmented areas can be seen that are nearer to the observer than the retinal arteries, these spots are situated in tlie retina. If tlie spots, either light or dark, are farther away from the observer than the retinal vessels; in other words, if the retinal vessels run over the spots, they are in the choroid. Remembering the things to be remembered and forgetting the things that are to be forgotten, the individual pictures will now be observed in the schematic eye; but before doing this, the student will be especially cautioned to remember two rules. First, the strongest plus lens zcith tchieh he can see the screen in the model measures the hifpermetrojJUL Second, the zceakest minus lens zcith zchich Ju can see the screen measures the mi/opia. It is very important to remember these tzco rules. It will be natural for the observer to put on glasses with which he can see the screen best, but that would be wrong. The strongest convex ( -\-) or weakest concave ( — ) lens with whicli he can see the screen at all is the correct one. Ophthalmoscopy must be mastered before much progress can be made in the study of opli- thalmology, and the student is urged to study the following pictures very carefully. They can be studied without a model but the use of this device simplifies the subject, develops skill, and makes oplithalmosco]:)y simple, easy, and interesting. 18 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Dark Normal Fundus Plate I. OPHTHALMOSCOPY 19 XoKMAL Dark Fundus: Plate 1 represents a (lark normal fundus. The lif^ht streaks that would be found in the human (retinal) arteries, are absent as they are in all the following pic- tures. Otherwise it is a true reproduction of a dark normal fundus. Retinal Vessels: The retinal vessels are seen emerging from the center of the optic nerve and passing across the fundus in a normal man- ner, ihe veins being one-third larger than the arteries. The Nerve Head: The nerve head appears slis^htly hvperaemic but its color and also the color of the whole fundus should be overlooked, because it has been emphasized that the student in his early studies should ignore the color of the fundus and optic nerve. \'\nien the moimted copy of the above plate is studied in the model adjusted to make it either normal or hypermetropic, "short'' the screen will be seen when it is observed through the aperture of the ophthalmoscope. Plus ( + ) lenses sliould be turned before the aperture of the ophthalmo- scope as long as the screen can be seen and the strongest one with which this can be done will register the amount of hypermetronia. The model can then be made lono\ "mvopic" and the weakest minus ( — ) lens with which he can see the screen, will record the amount of myopia. AM of the following plates should be studied in this manner in order to obtain practice in measuring refraction because the eve must be re- fracted before anv diagnosis can be made. 20 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Light Normal Fundus Plate II. OPHTHALMOSCOPY 21 Normal Light Fundus : Plate 11 represents a normal light fundus with the retinal vessels emerging from the center of the optic nerve and coursing across the fundus in a normal manner. Xerm^: Hp:au: The nerve appears to have the same color as the fundus with a light spot in its center, the scleral ring extends half way around the nerve head on the nasal side, and the choroidal ring extends nearly half way around the nerve head on the temporal. Choroidal and Scleral Rings: The choroi- dal and scleral rings may be absent or much more marked in normal eyes, but they sliould also be ignored when looking for pathological lesions. XoRMAL Findings : In this picture as well as Plate 1, the student's attention is called to normal findings. The general background may vary from the lightest to the darkest and yet the eye remain normal. This picture should be studied in the model in the manner described in the discussion of Plate I. Fig. 6. Noi-mal cross secti Normal Cross Section : Figure 6 represents a cross section of Plate 11. The student will notice that there are no elevations or excavations at the nerve head, or in any part of the fundus. 22 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Myopic Crescent Plate III. OPHTHALMOSCOPY 23 Myopic Ckkscext: Plate III. The retinal \essels are normal and tlie ehoroidal vessels, broader than those of the retina, show through the latter and there is a large Avliite crescent on the temporal side of the nerve head. When such a pictiu'e is found in a myopic oa*J.ong e^^e, a diag- nosis of mj^opic crescent is made. Save for the large crescent at the side of the optic nerve, the picture is normal. In low degrees of myo])ia, the fundus often presents a normal appearance; but the above is very fre(]uently found in high de- grees. Diseases of ]Myopia: The student is re- minded that a variety of lesions may be found in high degrees of myopia, (near sighted eyes) such as choroiditis, uveitis, detachment of the ret- ina, dislocated lens, and even general destruction of the eye ball. CHAPTER II Diseases of the Retina: The five colored plates that follow represent the commoner dis- eases of the retina, and they should l)e carefully studied with the ophthalmoscope in the model. The model should he made short, "hypermetro- pic" and the refraction carefully measured, then long, "myopic" and the refraction again meas- ured. This should he done in order to acquire an idea of elevations and excavations, which must be done in order that a diagnosis can be made. This exercise will be found to be quite satisfac- tory upon the model. It is the intention of the author to give the student and practitioner a working knowledge of ophthalmoscopy and describe a few pictures of lesions usually found in the fundus; the rare ones are not mentioned. If the following pictures are carefully studied in conjunction with the use of the model, the student will be well prepared to make diagnosis of diseases of the fundus as he Avill meet them. A beginner in tlie study of diseases of the eye is usually early in forming ideas regarding dis- eases of the fundus ; he begins as a rule by imag- ining diseases that are next to impossible. If the normal eye and gross lesions are well under- stood, the lesser lesions soon become simple. A greater number of diseases of the retina would only have a tendency to complicate tlie subject. 26 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Detachment of Retins Plate IV. DISEASES OF THE RETINA 27 Detach:ment of the Retina: Plate IV. There is a large white crescent extending more than half around the nerve head ( Posterior stap- hyloma). The upper part of the fundus is red and the lower part is of a lighter color and is in folds. The upper ])art a])pears red I)ecause of the choroid immediately under the retina wliile the lower part is of a lighter color, hecause the choroid cannot he seen, as the result of there heing something hetween it and the retina. The retinal vessels pass over the entire fundus hut the stu- dent will notice tliat they seem to he hroken at the edge of the detachment, or at the junction of the light and red areas. A similar picture is seen in sarcoma of the choroid, but a striking differ- ence is seen when comparing the retinal vessels of detachment with those of sarcoma. ( See Plate X.) A break will be observed at each told ot the retina in detachment, while in a sarcoma, breaks will be seen only at the junction of the light and red areas because of the absence of folds in the latter. Tension : In detachment of the retina the eye is usually below normal. Hyper:\ietropia: In both detachment of the retina and sarcoma, the affected areas are more hypermetropic than the normal part of the fun- dus. If unable to make a differential diagnosis between the two conditions by the a])])earance of the involved retinal vessels, the doubt can usually be easily cleared u]) by puncture of the sclera 28 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION over the affected portion after cocainizing the eye. If the lesion proves to be a detachment, fluid will escape and the retina will be temporarily replaced in position as can be determined with the ophthal- moscope. Should it be sarcoma, there will be no change in position or size of the tumor. Fig. 7. Detachment of Retina. Cross section Plate IV Figure 7 represents a cross section of Plate IV. The student will note the elevation or hy- permetropia of the detached portion. If the re- fraction is made with the ophthalmoscope at (A) and then at (B) without removing the ophthal- moscope from the eye, the difference in the re- fraction will be easily measured. Elevation: When measuring the refraction of two portions of the fundus, a refractive differ- ence of 3 D. is equivalent to a difference of 1 millimeter in level. The student will shortly become adept at estimating the height of any elevations or depth of any depressions he may meet. Prognosis : Usually blindness. Treatment: Rest in bed, laxative, sweats, potassium iodide, sub-con junctival injections of 1 to 3% salt solution or 5% citrate of soda; draw DISEASES OF THE RETINA 29 off fluid by puncture or trephine the sclera after laying back the conjunctiva and exposing it, after which the opening is closed with one or two sutures. 30 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Retinitis Pigmentosa Plate V. Retinitis Pig:\ientosa: Plate V. The reti- nal vessels are normal and the scleral and choroi- dal rings are plainly visible. The background of the fundus is dark, spots of pigment are noticed, which are seen to be deposited on the retinal vessels. When the fundus is examined with the ophthalmoscope, the retinal vessels dis- appear first, when plus glasses are used, showing clearly that the spots are in the retina.T) DISEASES OF THE RETINA 31 There is no difference in the ophthalmoscopic pictures of retinitis pigmentosa and ac(|uired syphihs; but the former always appears in child- hood showing itself symptomatically by com- plaint of the early onset of darkness toward the close of the day, even long before normal individ- uals note any failure of the illumination. This symptom alone occurring in a child is sufficient for a positive diagnosis of retinitis pigmentosa without the ophthalmoscopic picture. External examination does not reveal any symptom of disease. Figure 8 represents a cross section of Plate V. The student will note that the pig- mented spots are in front of the retinal vessels and can easily be distinguished from choridal pigment by meas- urement of the refraction of one or more of the s])ots and of an adjacent nor- mal area ^vith the o])hthalmoscope as described on Plate IV. PiKKiXOSis: Blindness usually occurs about middle life or a little later. Treatment : No treatment has as yet been found to be of benefit. However, errors of re- fraction should be corrected. Fig. 8 Retinitis Pigmen- tosa. Cross Section Plate V. 32 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Retinitis Pigmentosa with Oblong Disc (Luetic Retinitis) : Plate VI. This picture is produced in acquired syphilis; occurring only in adults and closely resembles retinitis pigmentosa. The spots of pigment are plainly in front of the retinal vessels; whereas, if thc}^ were in the choroid, the vessels would be anterior to the spots. Retinitis Pigmentosa with Oblong Disc. Plate VI. In observing the pictures in the model, the spots will be seen after the arteries have disappeared when plus lenses are introduced into the aper- ture of the ophthalmoscope, thus showing the spots to be on the retina. The nerve head is oblong to represent astigmatism, but it does not have any relation to lues. DISEASES OF THE RETINA 33 Fig. 9. Luetic Retinitis. Cross section Plate VI. Figure 9 represents a cross section of Plate VI and is inserted to impress upon the student's mind the location of the pigmented spots. The student will recognize that it is not a difficult matter to determine their location with the ophthalmoscope, it being noted whether the spots or the vessels disappear last when plus lenses are introduced into the ophthalmoscope. If the spots are seen after the vessels have disappeared while increas- ing the plus, they must be in the retina; and, if the spots disappear first they must be in the choroid. Prognosis: If active but without too much destruction in the back of the eye, the ]:)rocess can often be arrested. If the lesion is old, the same treatment should be tried, but Avith less hope of improvement. Treatment: If in a state of active inflamma- tion, salvarsan or mercury and large doses of potassium iodide should be given : but if inactive, treatment of any kind is usually unsatisfactory. Errors of refraction if any, should, of course, be corrected. 34 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Embolism Central Retinal Artery Plate VII. diseases of the retina 35 Embolism of the Central Artery of the Retixa: Plate VII. The nerve liead is blurred and there is a light area on its temporal side, cov- ering the entire macular region, save for one small red spot. The patient gives a history of sudden loss of vision. Figure 10 represents a cross section of Plate VII. The student will note that there is no Fig. 10. Embolism Central Retinal Artery. Cross section Plate VII. elevation of the fundus shown in the light area, as there would be if a tumor, exudate, or detach- ment of the retina were present. (See Plate IV and Figure 7.) Prognosis: Blindness in the affected eye with- out any external manifestations. Treatment: Massage, paracentesis and iodide of potassium have been recommended: but the results are usuallv unsatisfactorv. 36 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Retinitis Albuminurica Plate VIII. DISEASES OF THE RETINA 37 Retinitis Albuminurica: Plate VIII. The nerve head is not swollen as in choked (hsc, Plate XX, XXI and XXII, nor is it pushed back as in glaucoma Plate XXIII and XXIV, hut is pale as in atrophy Plate XVIII. The choridal vessels Avhich are wider than those of the retina, can be seen through the latter and tliere are hemorrhagic spots scattered throughout the fimdus. The principal lesion, which is described as a stellate picture commencing in tlie macular re- gion, is typical of this disease, is well marked and a diagnosis can easily be made by anyone who can reflect the light into the eye and illu- minate its interior. While this picture is particidarly typical, most of the pictures of albuminuric retinitis are not so much so. The student should examine the urine of any patient in whom the diagnosis is not plain. iMany diagnoses are thus made perfectly clear where only a slight lesion is found in the macular region. Prognosis : Very grave. Treatment: General treatment of nephritis but with no hope of restoring vision. The urine, tonsils, teeth, sinuses and a general examination should be made for the source of infection. 39 CHAPTER III Diseases of the Choroid: The eight follow- ing pictures fairly represent the disease of the choroid. They should be carefully observed in the model and the refraction measured in order to be able to make the all important differentia- tion between excavations and elevations. If these eight ]Mctures are carefully studied as described, very little trouble will be found in diagnosing diseases of the choroid when an exam- ination of the patient is made: the author believes that more illustrations would only complicate the subject as designed for students and general practitioners of medicine. 40 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Coloboma of the Choroid Plate IX. DISEASES OF THE CHOROID 41 CoLOBOMA OF THE Choroid: Plate IX. The scleral and choroidal rings are well marked. The whole fundus is a normal red save in the lower part which is white. The strongest plus glass with wliich the screen can he seen on the red part of the fundus would indicate the refraction at that part of it, and the same measurement of its white portion would indicate the refraction at that point. If the red or normal part of the fundus measured the same as the white it could only be a coloboma of the choroid. In this picture, the choroid is congenitally ab- sent and the sclera is seen shining through the transparent retina and the retinal vessels are seen with a white sclera as a background. A coloboma of the iris is often found with a coloboma of the choroid, and presents the picture of a more or less complete iridectomy. The student is reminded to measure the refrac- tion on the red part of the fundus which is desig- nated as normal and without removing his eye from the picture, to measure that of the white ])art of the fundus. Figure 11 represents a cross section of Plate IX. The stu- dent will contrast tliis ])icture with figure 7 and Plates IV and X. Here there is no ele- vation above the normal, while Fig. 11. Coloboma of 1^ flgurcs ,5, 7 aud 12 the ele- ''s'ec«on"pYate f£" N^tioU is Wcll Uiarkcd. 42 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Sakcoma of the Choroid: Plate X. The scleral and choroidal rings are well marked, ex- tending all around the nerve head, the upper part of the fundus is red and the lower part light. The retinal arteries are seen to course over the red part of the fundus where the choroid is giving the fundus its red color as well as over the light part below, where there is something between the retina and the choroid. Sarcoma of Choroid Plate X. Hypermetropia: The sarcoma is always more hypermetropic than the red or normal part of the fundus. Compare with coloboma of the choroid (Plate IX), where there is a large hght area in the fundus but which is not more hyper- metropic than the normal. DISEASES OF THE CHOROID 43 Vessels in Sakco:ma: There is a distinct l)reak in the retinal vessels at the junction of the red and light areas such as is found in detachment of the retina (Plate IV). After the vessels have passed on to the sarcoma, there are no hreaks as are found in the former. Tension in Sarcoma: A sarcoma is not caused by low tension or soft eye as in detachment of the retina as it simply grows into a readily displaced watery body. The tension of the afiPected eye may either be normal or plus in the first stages of the disease. A sarcoma may be- come quite large without producing increase of tension, but later it always causes plus tension. It is impossible to make a diagnosis of sarcoma of the choroid, without the ophthalmoscope, be- cause the eye does not show any symptoms externally. If the vitreous and lens are clear the diagnosis is plain, especially with the use of the technique descril^ed for differential diagnosis under Detachment of the Retina (Plate IV). Figure 12 is a cross section of Plate X showing the elevation of the sarcoma above the normal fundus. A, the elevation; B, the normal. Fig. 12. Sarcoma of the Choroid. Cross section Plate X. 44 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Posterior Staphyloma with Choroiditis Plate XI. DISEASES OF THE CHOROID 45 Pkognosis : The growth may recur in the eye socket after enucleation, or in some other organ. Tbeatment : The eye should be removed and with it as much of the optic nerve as possible, followed by X-Kay treatment. If the tissues around the eye are involved, all the structures of the orbit should be removed. Posterior Staphyloma avith Choroiditis: Plate XI. The retinal vessels are normal, the scleral ring is very large, and the choroidal ring is well marked. There is a large light atrophic spot at the temporal side of the nerve head, (pos- terior staphyloma) ; many white spots are scat- tered over the fundus, and the retinal vessels seem to run over them. The spots are all choroidal ; and, if the patient is myopic, the retinal vessels could be seen only with a minus glass. The student is reminded that in Plates V and VI the pigmented spots were in front of the retinal vessels wliile in this picture the vessels are in front of the spots. In those plates the lesions were in the retina; but in this pictiu'e the lesion is in the clioroid. Prognosis : Rarely good. Treatment: Glasses should be ])rescribed if necessary, but local treatment of the eye is use- less. The urine should be examined and any general treatment tliat is indicated should always be given, having in mind the effects of lues upon the eye. 46 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Disseminated Choroiditi Plate XII. DISEASES OF THE CHOROID 47 DissEMiXATEJ) CiioKOiDiTis: Plate Xll. The scleral and choroidal rings are well marked and the nerve head is not swollen as in choked disc, (Plates XX and XXI), nor cupped as in glau- coma, (Plates XXIII and XXIV). The retinal vessels are normal. The only pathological lesions present are the atrophic spots in the choroid. The sclera can be seen shining through the red choroid and the retinal vessels run over the atrophic spots. Vision : The reduction of vision depends upon the location of the lesion in the choroid and the refraction of the eye. As long as the macular region remains free from disease central vision may be expected to be retained. Prognosis: Grave if macula is involved. Treatment : Constitutional treatment and correction of errors of refraction. 48 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Rupture of Choroid Plate XIII. DISEASES OF THE CHOROID 49 Rupture of Choroid: Plate XIII. The retinal vessels and the nerve head are normal. There is an atrophie spot with a pigmented horder at the temporal side of the fundus. A diagnosis of rupture of the choroid, impossi- ble at the time of injury because of hemorrhage into the vitreous, is made later from the ophthal- moscopic picture together with the history of injury. Vision : Loss of vision depends upon the ex- tent of the injury, and the location of the rupture. If it be on the temporal side, the loss of central vision will naturally be greater than w-ould occur if the rupture w^ere in some other part of the fundus. Prognosis : Depends upon the location of the rupture ; the nearer the macula the less favorable the prognosis. Treatment: At the time of injury two drops of 1% solution of atropin sulphate should he dro])ped into the eye three times a day together with such other treatment as is indicated. Potas- sium iodide is indicated for absorption. 50 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Central Choroiditis Plate XIV. DISEASES OF THE CHOROID 51 Central Choroiditis: Plate XIV. The lesion represented here is an extensive choroiditis. It occupies the entire macular region, and it would be impossible for anj^one to make a mis- take in diagnosis, providing he had a working knowledge of the ophthalmoscope. Such a lesion could be the result of trauma or any disease that would produce a choroiditis. Prognosis : Bad as regards vision. Treatment : None. 52 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Central Choroiditis (slight) Plate XV. DISEASES OF THE CHOROID 53 Central Chokoiditis: Plate XV. The scleral and choroidal rings are well marked and the retinal vessels and nerve head are normal. Three small wliite spots /ire seen on the temporal side of the fundus in the macular region. A diagnosis of central choroiditis can he made hecause spots in this region, either ])igmented or atrophic, are always the result of central choroid- itis. The fovea centralis is often very w^ell marked hut it is single and could not be mistaken for central choroiditis. Vision : If the vision is normal there coidd not be a central choroiditis; but if the vision is re- duced, a slight change in the macular region may be the cause of it. Prognosis: The loss of vision is usually per- manent unless a specific cause is found and treated. Treatment: Entirely constitutional. 54 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Injury Plate XVI. DISEASES OF THE CHOROID 55 Injuky — Plate XVI. This picture is that of a perfectly normal fundus, save that a piece of steel has penetrated the eye, becoming embedded ^- in the sclera and is surrounded by blood. A lesion in this location is not ordinarily as grave as if it were nearer the macula and pro- duced by disease (Plates XIV and XV) ; but in this case, the prognosis is ver^^ grave because of the lesion liaving been produced by a foreign body, which has been retained within the eye ball. Prognosis : Grave. Treat:ment: Remove the steel with the giant magnet if the injury is recent and treat as any injury of the eyeball; sulphate of atropin 1%, 2 drops in the eye three times a day. If injury is of Ions: standing enucleate the eve. X-Rav examination shoidd be first made in all cases and foreign body localized. It is not the purpose of the author to describe the treatment of injuries of the eyes; but it is always good practice to remove eyes that are blind and irritated, because the danger to the fellow eye is all important. 57 CHAPTER IV Diseases of the Optic Nera:e: The follow- ing six colored plates with a consideration of the field of vision will give the student or ])ractitioner a good practical working knowledge of diseases of the optic nerve. Diseases of the optic nerve can often he diagnosed only hy study of the field of vision in conjunction with ophthalmoscopy. iNIore pictures than are here described would have a tendency to confuse the student and com- plicate the subject. A discussion of the method of taking a field will be given on page 76. 58 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Glaucoma with Atrophy Plate XVII. DISEASES OF THE OPTIC NERVE 59 Atrophy of the Optic Xer^^ with Glau- coma: Plate XVII. The scleral and choroidal rings are Avell marked but there is a marked difference in the size of the retinal vessels. AVliile the veins are normal, the arteries are noted to be small and threadlike. This condition alone would justify a diagnosis of optic atropliy: ])ut, in order to l)e absolutely certain, tlie field sliould be taken in each eye if enough vision remains to make it possible. This plate also presents a ])icture of glaucoma, which condition will be taken up in a separate chapter, the cupping of the nerve head being shown by the apparent dipping down of the retinal vessels at its margins and proved posi- tively by measurement of the refraction as de- scribed under detaclmient of the retina. (Plate IV.) Prognosis: Of optic atrophy grave. Glau- coma, see page 71. Treatment: Atro])hy-Salvarsan or mercury and large doses of ])otassium iodide may be tried : but, if a positive diagnosis of atro])liy lias been made, treatment is usually useless. Stryclinia is recommended by some. If glaucoma, see ])age 71. 60 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Optic Atrophy Plate XVIII. DISEASES OF THE OPTIC NERVE 61 Optic Atrophy: Plate XVIII. The student has been cautioned regarding the color of the optic nerve in atrophy; but, in this ])icture the patient is blind which ])revents taking the field and the diagnosis must be made from the white disc and threadlike arteries. The veins are nor- mal in size. Field: If the patient can see well enough to permit the taking of the field, it should always be done in each eye. When a concentrically contracted field is found the student can be sure of his diagnosis no matter what the ophthalmo- scopic findings may be. This rule should be remembered. Arteries: If the arteries are threadlike and the veins normal as in Plate XVII, a diagnosis of atrophy can be positively made without taking the field ; ])ut it is wise to do so in all suspicious cases. Prognosis: "N^ery grave: vision usually totally destroyed in time. Treatment: Salvarsan or mercury and large doses of potassium iodide may be tried. Strych- nia is recommended. ])ut treatment is usually of little avail. 62 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Opaque Nerve Fibres Plate XIX. DISEASES OF THE OPTIC NERVE 63 Opaque Ner^t: Fibres: Plate XIX. This picture is shown in order to describe opaque nerve fibres which, while they are of no sig- nificance, should be recognized when seen, so that they should not be mistaken for some patholog- ical condition. The white opaque nerve fibres usually follow the principal retinal arteries. This is a normal condition of the fundus of rabbits and is not infrequently met with in man. In the human eye however, so typical a picture as is here shown is not frequently observed; more often the condition is present only in one or two areas adjacent to the nerve head where the ves- sels are covered by the opaque nerve fibres. 64 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Plain Choked Disc Plate XX. Choked Disc : Plate XX. The nerve head is swollen and the diagnosis can be made positively because when the fundus is examined, the re- fraction is found to be higher at the nerve head than aAvav from it. DISEASES OF THE OPTIC NERVE 65 Hypermetropic Xerve: The student is cau- tioned to measure the refraction of the fundus in all cases at about one diameter of the nerve head from the nerve and when this is done, to measure it at the edoe of the nerve head. If the latter be more hypermetropic than the other parts of the fundus, a diagnosis of choked disc may be positively made. It is important that the practitioner make a diagnosis of choked disc early because it is then usually amenable to treatment ; and if not prop- erly treated, optic atrophy and blindness may follow. If the choked disc is only in one eye the cause may be found in the sinuses; but if in both eyes the cause must be looked for in the cranial cavity. Figure 13 represents a cross section of Plate XX. The swelling of the nerve head can be readily seen. Prognosis: Favorable, un- less from malignant tumor of the brain. Treatment: If the condi- tion is unilateral, which rarely occurs, very often appro])riate sinus treatment will effect a cure. If l/ilateral and due to tumor of the hypopliysis, the gland should be removed. Usually however, the t^-eatment offering the greatest hope of benefit is the administration of salvarsan or mercury with large doses of potassium iodide. Fig. 13. Choked Disc. Cross section Plate XX. 66 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Neurorentinitis Plate XXI. DISEASES OF THE OPTIC NERVE 67 Neuroretixitis: Plate XXI. The only difference between this picture and Plate XX, is the twisting of the retinal vessels and more swell- ing of the optic nerve. The nerve head is swollen and the retinal vessels are tortuous. The diag- nosis is that of a lesion both of the optic nerve and the retina (Xeurorettxitls) . Fig. 14. Choked disc. Cross section Plate XXI. Figure 14 represents a cross section of Plate XXI. The diagnosis is readily made from the swelling of the nerve and the twisting of tlie ret- inal vessels. Prognosis: Is the same as in Plate XX. Treatment: Is the same as in Plate XX. 68 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Papillitis Haemorrhagica Plate XXII. DISEASES OF THE OPTIC NERVE 69 Papillitis Hemorrhagica: Plate XXII. The nerve head is swollen, the retinal vessels are twisted as in Plate XXI and tlie fundus is stud- ded with hemorrhages some of whieh are lighter than others, indieating their more recent occur- rence. Fig. 15. Papillitis Hemorrhagica. Cross section Plate XXII. Figure 1.5 represents a cross section of Plate XXII. If the media are clear, a diagnosis can readih^ be made and the amount of swelling of the nerve can be readily measured Avith the ophthalmoscope. Prognosis: Is the same as in Plate XX. Treatment: Is the same as in Plate XX. 70 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Glaucoma Plate XXIII. DISEASES OF THE OPTIC NERVE 71 Glaucoma: Plate XXIll. The retinal ves- sels are normal in size but they do not emerge from the center of the nerve as in normal eyes, (Plates 1 and 11) but seem to stop and disappear at the edge of the nerve head. If the eye is refracted, the bottom of the cup or center of the nerve head will be found to be more myopic than the surrounding fundus. The arteries may pulsate and the field is usually con- tracted and to the nasal side. In such a case the tension may be high, the cornea anesthetic, the anterior chamber hazy and shallow, the lens clear, the vitreous clear, but the ophthalmoscope discloses this typical . picture of glaucoma. Fig. 16. Glaucoma. Cross section Plate XXIII. Figure 16 is a cross section of Plate XXIII; there is a pushing back of the nerve head. The excavation can be as readily measured as an ele- vation was measured in the other plates. The difference in refraction between the normal part of the fundus and tlie bottom of the depression will represent the depth of the cupping. Prognosis: Guarded — seepage 112. Treatment: See page 112. 72 OPHTHALxMOSCOPY, RETINOSCOPY AND REFRACTION Haemorrhagic Glaucoma Plate XXIV. DISEASES OF THE OPTIC NERVE 73 Hemorrhagic Glaucoma: Plate XXIV. Tlie retinal vessels are normal in size but do not emerge from the center of the optic nerve as in normal eyes. (Plates I and II.) They appear to stop at, and dip back from the edge of the optic nerve. (Plate XXIII.) The center of the optic nerve is more myopic than the normal part of the fundus and hemorrhages can be seen, some dark and some liglit, the latter being more recent. Fig. 17. Hemorrhagic Glaucoma. Cross section Plate XXIV. Figure 17 represents a cross section of Plate XXIV; the cupping can be readilv measured as in Plate XXIII. Prognosis: Grave. See page 112. Treatment: See page 112. FIELD OF VISION Direct and Indirect Ophthalmoscopy CHAPTER V. The Field of Vision: The field must be studied in connection with ophthahiioscopy, be- cause some diseases of the fundus that at first seem obscure, are made perfectly clear when the field is considered; and there are some diseases that are impossible to diagnose without the tak- ing of the field. Without A Perimeter: The first thing to do in taking the field without a perimeter will be to take a small piece of paper, one quarter of an inch square, red on one side and white on the other. Hold it in front of the patient by inserting it between the points of a pen (Fig 18) and see if he is color blind. FIELD OF VISION 75 Fig. IS. Testing field for colors 76 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Central Scotoma for Red: The examiner rotates the penholder and the red and white are alternated. When the patient looks directly at the paper he is instructed to cover one eye and look into the examiner's eye with the other. If the red color does not appear red when placed in his direct vision, or between the examiner's eye and that of the patient, and does seem so to him when the paper is moved away from the center of his field, he has a central scotoma for red. Treatment: Remove the cause which is usually alcohol or tobacco and give eliminatives and 1/30 grain sulphate of strychnine qid. If there is no central scotoma for red, next determine the extent of the fields for the various colors by comparison with your ow^n. To test the right eye, the patient is placed in such a position that his eyes will be on a level with the examiner's eyes; and the light from the window will fall equally on his right and on the examiner's left side. The examiner's right and the patient's left eye should be closed and both should look steadily at the pupil of the other. (Figure 19) . The positions are reversed for ex- amination of the left eye, in order that proper illumination may be obtained. Figure 19. Comparison of Examiner's and Patient's fields. A piece of paper, red on both sides and one-quarter inch in diameter is now inserted into the pen. This paper should be moved in a plane midway between the examiner's eye and that of the patient, the examiner and patient looking into each other's eyes. Both FIELD OF VISION 77 Fig. 19. Taking field without Perimeter 78 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION should see the paper and distinguish its color about the same time if both have normal fields. This can be done with white as well as with all the colors and, if the field is carefully taken, the student will be able to detect any deviation from the normal. With Perimeter: If the field seems sus- picious with this examination, it should be taken with the perimeter (Figure 20 and 21) or with the campimeter (Figure 22). Fig. 20. Perimeter (Meyrowitz), Fig. 21. Perimeter (Geneva). A number of abnormal fields that are typical of the conditions in which they are found are inserted for the consideration of the student and that he may properly appreciate them a normal field is shown. FIELD OF VISION 79 Fig. 22. Ciimpimeter Fig. 23. Normal Field (Jennings) Fig. 24. The field of vision in Glaucoma. Left eye. Peripheral contraction especially on the nasal side. (May) 80 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION He will note especially the extent of the in- dividual fields for the various primary colors tested for. All of which were tested with discs 1/4 inch in diameter. Glaucoma : The field is contracted below and to the nasal side. For prognosis and treatment see page 112. Optic Atrophy: The field is concentrically contracted for white and colors. Prognosis : Grave. Fig. 25. Field of vision of the right eye in a case of optic-nerve atrophy. The white field is slightly contracted, the color fields markedly restricted. (deSchweinitz) Treatment: Mercury and Iodide of Potas- sium should be given a trial. Strychnia is also recommended. MKIJ) OK VISION 81 'nk Fig. 26 and 27. Homonymous Hemiopia (^Schweigger) Hkmixopsia: Fio-. 2i\ and Fig. 27. 'I'hc fields are entirely cnt off on one side. Fields in right homonymous heminopsia. Pkoqnosis: Fields usually remain unchanged. Tkeatment: If specific, salvarsan, mercury and large doses of iodide of ])otassium. If in elderly patients and of unknown causation, give fifteen grains of the latter four times daily. Retkobular Xeuritis : Toxic Amblyopia: There is a spot in the center of the field where the ])atient can- not recognize the color of a small piece of red ])aper — central scotoma for red. Figure 28. Field in Uet- rohular Xeuritis. Prognosis: Good if treated early. Treatment: Remove the cause which is usu- all}^ tobacco or alcohol or l)()th and give strychnia per mouth or hypodermically. Fig. 28. Field in Toxic Am blyopia. (F^chs) 82 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Hysteria: The fields overlap, that is, the green which usually lies wholly within that for the red is found to be larger and overlapping it in places. It also changes at different exami- nations or even when successively taken at the same sitting. When the field is being taken, even if carefully done, it will a])pear to change. The following two very different fields were se- cured by a careful operator within an hour on a patient with a well authenticated diagnosis of hysteria. Figure 29. Field in Hysteria. Figure 30. Field in the same case one hour later. Such a variation would not occur in other diseases, and the general practitioner should understand this important condition. Prognosis : Good. However, the patient will often complain that the vision is much impaired or even sometimes claim nearly complete blind- ness. Fig. 29. Field in Hysteria Fig. 30. Field in Hysteria FIELD OF VISION 83 Treatment: Prescribe the proper glasses for the correction of any refractive error found, and give the general treatment indicated for this con- dition. Some placebo may be dropped into the eyes as for instance, sodii biboratis gr. V to oz. one everv three liours. Fig. 31. Oblique Illumination o4 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Systematic Eye Examination: When the student has mastered the schematic eye, he will be prepared to examine a patient; but it is un- wise to attempt to do so until he finds the schematic eye easy to examine, even with a small pupil and has mastered the technique of oblique illumination which he will find useful in all cases as well as ophthalmoscopy. Oblique Illumination: Condensing lens used in indirect ophthalmoscopy. Illumination of the part under inspection by means of a strong convex lens. By this means, the illumination is markedly increased and minute details are made visible. This method of examination is always used for searcliing for foreign bodies upon or in the cornea. Light : The source of light can be from a gas, kerosene, candle or electric liglit, with a frosted globe or the light from a window. The con- densing lens used in connection with direct ophthalmoscopy can be used for condensing the rays of light. Indirect O p hth alm oscopy When practicing indirect ophthalmoscopy (Figure 32) the patient is requested to look be- yond the student's right ear when the right eye is examined, or left ear if the left eye is examined: the light is reflected into the eye from a distance of about twenty inches with the mirror of the ophthalmosco])e tilted towards the light in the same manner as in the study of the schematic eye. A + 3 D. lens is placed in the ophthal- FIKLD OF VISION 85 mosc()])e and a -f^ 20 1). -that used for bifocal examination — is held two inches in front of the patient's eye, when an inverted picture of the fundus will be seen in front of the + 20 1). lens. The whole fundus can be studied in this manner and all parts of it can be brought into Fig. ;i2. Indirect Ophthalmoscopy 86 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION view by moving the + 20 D. lens from side to side and up and down. The indirect method is usually employed when the eyes of children are to be examined, or when the patient has lost the vision of one eye; and in all other e^^es where the direct method cannot be employed. Direct Ophthalmoscopy. First Position: Figure 33. Represents the correct first position of observer and observed in practicing direct ophthalmoscopy. The same rules are to be ob- served as when the model is being used. To examine the right eye, the light is placed on the patient's right side on a level with his eye. Position of Observer: When the right eye is to be examined the observer sits in front and to the right on a revolving stool that has been ad- justed to the proper height. Before beginning the ophthalmoscopic examination, the patient is instructed to look across the room at some fixed point and is also told to close both eyes if the observer should get in front of him, thus keeping him from seeing the object selected. The student will soon learn to keep his head out of the patient's line of vision and will readily acquire a good position for examination. The patient will always keep his eye quiet and in one position if he has something for the un- observed eye to look at and he should always be instructed to look at some selected spot before beginning the ophthalmoscopic examination. The mirror of the ophthalmoscope is tilted to- wards the light which is now reflected into the eye FIELD OF VISION 87 FiK 33. Direct Ophthalmoscopy. First position 88 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 34 Direct Ophthalmoscopy. Second position FIELD OF VISION 89 under examination. As soon as the light is re- Heeted into the eye, the pupil will appear red and the approach to the second position is begun. Second Posijiox : Figure 84. llepi-esents the second position lor dn*ect ophthalmoscopy. The student approaches the patient from the first position and comes as close to the o])served eye as possible without losing the red reflex. The student must keep both of his eyes open and relax his accommodation as mucli as possible by look- ing into the distance. If the refraction of the eye is normal or hypermetropic, the student will readily obser^'e the retinal vessels and optic nerve when the first thing to be done before losing sight of them is to refract the eye. If the eye be myopic, the details of the fundus can be seen only with minus glasses. Light Streaks ok White Lines: It is es- sential to get an ophthalmoscopic ])icture that is not exaggerated, and to do this the student must refract the eye as he begins his ophthalmoscopic examination by looking through the a])erture of the instrument. If the light streaks on the retinal vessels can be seen with the ()phthalmosco])e in this manner, the eye is either normal or hy])er- metro])ic. The student should now add 1 1). to his ophthalmoscope and, if the white lines on the arteries disappear, he will know he is dealing with a normal eye: but, if they can be seen with a + 1 D., he will know lie is dealing with a hy])ermetro])ic eye and must ])ut on stronger plus lenses until the white lines disappear. The 90 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION strongest plus glass with which the light streaks or white lines can be seen at all, will represent the amount of hypermetropia. If the eye is myopic, the weakest minus glass with which the white lines on the retinal vessels can be seen at all will represent the amount of myopia. ^^^ith these two rules in mind at all times, the student can readily detect elevations and exca- vations in the fundus, and, when this is done, he will be quite well prepared to make diagnosis of gross pathological lesions. He will be able to diagnose a swelling of the nerve head, a cupping of it, or an elevation of any part of the fundus. He will also be able to tell whether spots, either white or black, are situated in the retina, in front of the retinal ves- sels, or in the choroid — back of them. The student must observe the eye at close range which means that he should get as close to it as possible. Description of the Human Fundus : The picture of the himian fundus cannot be described because of the great variations in its color. The student will observe the same general normal points as he did in the pictures in the schematic eye. He will observe the optic nerve with the retinal vessels emerging from the center of it and passing across the fundus. If the retinal vessels all stop abruptly at the edge of the disc, it is a picture of glaucoma w^hich the student learned to recognize in the schematic eve. (Plate XXIII.) FIELD OF VISION 91 If the retinal vessels are tortuous, a picture of retinitis will be recognized as was learned in the study of the model. (Plate XXI-XXII.) If the nerve head is more hypermetropic than the normal part of the fundus the student knows he is dealing" with a case of choked disc. (I'ig- 13.) All this he has learned in the examination of the schematic eye. If some ])arts of the fundus are much lighter in color than othei-s, and it is higher at the light places than at other portions, the observer will at once be suspicious of either detachment of the retina, an exudate, or sarcoma of the choroid. The student is referred to the descri])tion of these two pictures. (Plates IV and X) which are the same as the pictures of the same lesion in the human fundus. If the student has mastered the schematic eye, he will experience no more trouble in making diagnosis of diseases of the interior of the eve than he will in making diagnosis of external diseases. ]Many doctors take the schematic eye too lightly and want to practice on patients before they have mastered it. Too great stress cannot be placed u])on tlie thorough study of the schematic eye. Ophthalmoscopy will be simplified if tlie hu- man eye is not studied until the student can examine the schematic eye without any effort. If he will then begin work on ])atients, he will find little difficulty in getting a good view of the fundus. 92 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The cases that appear obscure to a beginner in ophthahnoscop}^ usually are so because of his inability to illuminate the interior of the eye and see the pictures. If they can be seen, diagnosis will be made simple and interesting. If diagnosis of diseases of the interior of the eye is to be made simple, there is only one way to do it and that is to make ophthalmoscopy easy, which can only be done by becoming master of the o])hthalmoscope upon the model. Retinal Artekies Instead of Screen : The student will have the retinal vessel to deal with in the human eye, and he will have lost the screen, v/liicli he has been examining in the schematic eye. He will now substitute the white streaks on the retinal arteries for the screen and examine the human eye in the same manner as he did when dealing with the model. The Same Two Ruees to Remember: First, the strongi'st plus Jens xcith zdiieJi he ean see the tchite streaks on the retinal arteries AT ALL icill measure the hypermetropia. Second, the rceakest fuinus glass tcith ichieh lie ean see the xchite streaks on the retinal arteries AT ALL tcill measure the myopia. THESE TWO RULES MUST BE REMEMBERED. Distance of Examiner From Patient; The examiner should get as close as possible to the eye to be examined and at the same time not to lose his light. The patient's eyes should be examined in the same manner and the same two rules observed as in the examination of tlie schematic eye. FIELD OF VISION 93 Where Should the Patient J.ook: It is of the greatest iin})ortance that the ])atient I)e told to look at some point on the opposite side of the room. If the patient looks at this point and the observer sits at the side and not in front of him, he will hold the eye perfectly quiet. If the observer gets in front of the patient and prevents him from seeing the ol)ject given him to look at, the eye that is being observed will move and the student will have difficulty in examining it; but as long as the patient has a fixed point to observe with the eye that it is not being examined there will be no difficulty. A beginner in ophthalmosco])y should have the ])atient look at some object on the o])posite wall and instruct him to shut both of his eyes and keep them shut, if the observer's head obstructs his vision and kee])s liim from seeing tlie object. In this manner the student will soon acc^uire an easy and correct ])osition for the examination of an eye with the ophthalmoscope. Where Should the Exa:mtxer Look: The examiner should keep both eyes o])en and imagine tlie picture he is examining to l)e twenty or more feet from him. He will in this manner learn to relax his accommodation. Accovi:m()DATK)X : This is a great bugbear to a beginner. He becomes confused and thinks he must be acciu'ate in his measurements in order to be able to make diagnosis of })at]iological lesions. On the contrary, tlie ])rincipal thing necessary for him to do is to be able to recog- nize elevations and excavations in the back part of 94 OPHTHALMOSCOPY, RETINOSCOPY AND REFPIACTION the eye. To do this, it is imperative that he be able to measure the refraction at some normal point, and afterward to measure it at the ab- normal part witliout removing liis eye from the ophthalmoscope or changing his position. If the student makes a mistake in measuring the normal part of the fundus, he very likelj^ will make the same error in measuring the abnormal part. The only necessary thing to know is the difference between the two points, and he will soon find this not at all difficult. For instance, if the student is examining a swollen nerve, he first measures the refraction of a normal part of the fundus, usually about one diameter of the nerve head from it; he then measures that of the head of the nerve and the difference noted will represent the swelling of the nerve head. If the normal part of the fundus as measured by the student is + 3D. and the nerve head + 9 D., he will have 6 D. swelling. If he has made a mistake and had measured the normal part of the fundus + 6 D., would have made the same error at the nerve head and measured it a + 12. D. The difference would be the same and in either case he would have 6 D. or two milli- meters of swelling of the nerve head. Other ele- vations would be measured in a similar manner. Examination of Xormal Eyes: The stu- dent should examine as many normal eyes as possible because there is no better practice with the ophthalmoscope. The principal thing for a FIELD OF VISION 95 beginner to do, when making an ophthalmoscopic examination is to measure the refraction. He should first find the vessels in the fundus and then look for the light streaks on tlie retinal arteries and practice adding ])lus lenses in his ophthalmoscope until they disappear. If he cannot see the light streaks on the retinal arteries and must put on minus lenses to bring them out, he is dealing Avith myopic eyes. He should ])ractice ])utting on minus lenses to bring out the light streak on the retinal arteries remem- bering that the weakest one with which this can be done is the measure of the myopia. If the student will measure the refraction in every eye he examines, he will soon be able to recognize a normal fundus; and, when this is accomplished, there Avill be very little trouble in detecting existing lesions. Elevations and excavations can easily be meas- ured when the student illuminates the interior of the eye and can measure the normal fundus. When this is accom])lished, a choked disc, a glau- coma, a detached retina, an albuminuric retinitis, or a sarcoma of the choroid will be very simple matters to diagnose. XoT Xecessary to Remember Pictures: It will not be necessary to remember the picture of a lesion as seen with the ophthalmoscope, but rather to know when a fundus is normal, and if abnormal, to be able to point out the abnormal ])oints. Color of the Fundus: The general back- ground of the fundus is red but it may be very 96 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION dark or it may be very light red. The retina is a transparent membrane and the color of the fundus is produced by the vascular choroid. The normal nerve head sometimes appears red, or hyperaemic, and sometimes light, or anaemic. If the patient has normal vision, tlie student l^hould not pay much attention to the color of the optic nerve; but if the vision is ])oor, it should be studied carefully. Optic Atrophy: In atrophy of the optic nerve, the nerve head is white or gray; but the student should never depend upon the color of the nerve head alone. If he is suspicious of optic atrophy, the field should be taken if the patient has enough vision to make this possible. If the patient is not blind, the student can note the color of the nerve head but he can make a diagnosis of atrophy of the optic nerve by taking his field of vision long before he could be siu'e of such a diagnosis with the ophthalmoscope. Fields of both eyes should be taken if the patient has sufficient vision ; but if one eye is blind, the field of the good one should be taken. 97 CHAP IKK VI. Systematic Kxamixatiox of tiii: \\y\: It would be impossible to make a systematic examination of the eye without a Avorking knowl- i^dge of the oj)hthalm()sc()])e: i)iit even wliilc wv can make use of this small, inexpensive and im- ])ortant instrument, we have not as yet descril)ed any systematic method of examination witliout the careful following of which many im])ortant tilings woidd be overlooked. This systematic examination should be commenced from the front and proceed backward by certain definitely fixed steps. First Step: Inspection: Figure So. In- spection should cover all that can be seen without instruments, and a good light Fig. Ho A is indis- pensable. The cornea is the first structure exam- ined from front backwards. It is the seat of a great many eye affections coming under the care of general practitioners and should always receive a very careful examination for foreign bodies, ulcers and o]:)acities. The antci-ioi- chamber sliould l)e examined for o])acities and the ii'is and pu])il sliould be ex- amined together. The ])U])il sliould dilate Avhen covei'ed or pro- tected from the light and contract to the light when uncovered oi* when a light is reflected into the eye. After the anterior ])art of the eve ball has been inspected and the tension noted ( Figs. 87 tnid 41 ), the lower lid should be drawn down; the 98 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 35. Systematic Examination of the Eye ,,,ss«*^^ V, MUELLER i CO I jTrta Fig. 35a. Light SYSTEMATIC EXAMINATION OF THE EYE 99 conjunctiva inspected and the lachrymal sac pressed down. ( Figure 36.) If pus be pressed out of the lachrymal sac, a diagnosis of dacyryocystitis Avill be made ( Fig. 36). The upper lid should be everted for exami- nation by drawing it downward and away from the eye and turning it over a pencil. The motility of the e3^es can be observed by having the ])atient look up, down, right and left. If a diagnosis has not as yet been arrived at, the vision should be taken and a careful manifest refraction made. jMany doctors are satisfied with an examination less accurate than has been described, but those who can use the o])hthalmosco])e realize that a systematic examination has only been begun and that what is to follow, while not difficult, is of very great im])ortance. Second Step: The patient is now taken to the dark room, and, with a -f- 20 D. lens that accompanies the ophthalmoscope, the light is condensed into the eye and the cornea, anterior chamber, iris, pupil and lens are again inspected; and, if the cause of the trouble be not determined, the third step should be begun. Third Step: Tlie eye has now been examined from front backwards to the lens and we are ready for the most interesting and satisfactory l)art of an examination of the eyes, the use of the ophthalmosco])e. The first structure to be examined in the third step is the lens. This is done with the + 16 D. of the smaller disc ro- tated to position beliind the aperture of tlie in- strument. 100 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 36. Pressing upon the Lachrymal Sac. SYSTEMATIC EXAMINATION OF THE EYE 101 When the ophthalmoscope is 2^/2 inches from the patient's eye it will be in focus and any opacity in the cornea, anterior chamber or lens will ap])ear black, because they are opaque. A scar on the cornea that appears white by direct inspection will appear black like a piece of steel when seen with the ()])hthalmoscope. Incipient Cataract: Beginning opacities of the lens can l)e readily diagnosed with the ()])hthalmoscope; and, if the diagnosis can be made by the general practitioner, he may find the cause of the opacity by examination of the urine. If the physician can make a diagnosis of beginning of cataract, he can often treat his patient quite intelligently by giving attention to his general condition. If an opacity of the lens is found in a person over forty, that is not congenital or caused by an injury,, the probability of beginning cataract will be strong enough to warrant an examination of the urine. If the urine is found negative, and the vision not less than 20 40 a deep sub-con- junctival injection of 20 drops of one to 4000 cyanide of mercury is indicated, after cocainizing and injecting 20 drops of a 2% solution of cocain. If vision is less than 20 ^40, a good result cannot be expected. Fourth Step: The examination of the vitre- ous is made by reflecting the light into the eye from the o])lithahnosco])e at a distance of two feet from the eye and looking into the illuminated eye through the aperture, or + 8 D. at closer range. The patient is instructed to look up, then 102 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION down, right and left; if the vitreous is diseased, black opacities may be seen floating in it and a diagnosis of uveitis will be made. If the vitreous is clear the next step in the systematic examina- tion should be made. Fifth Step : The eye has now^ been examined from before backwards to and including the vit- reous. The examination of the fundus should never be attempted until a systematic examina- tion has been made of every structure in front of the retina. If this rule is observed, few mis- takes in diagnosis of what is to follow will occur. The observer should now plsice himself in the same j^osition relative to the eye as was described in Figure 33; and, when in position, should in- struct his patient to look at some point or spot on the opposite wall. Tell him too, that 3^ou will not obstruct the view of his object, and that if your head should get in his light, he must close both eyes and keep them closed until you tell him to open them. Red Reflex: The mirror of the ophthalmo- scope is now tilted toward the light which is re- flected into the eye at a distance of about two feet. As soon as the student reflects the light into the pupil, the red glow is seen and he ap- proaches the eye as quickly as possible, without allowing the light to get out of tlie ]:)U])il. (Fig- ure 34.) White Line: The student while approach- ing the eye and through the examination, keeps both eyes open. If the eye is normal or em- metropic, the white lines in the arteries disappear SYSTEMATIC EXAMINATION OF THE EYE 103 when a plus k ns is placed behind tlie aperture of the ophthalmoscope. If the white lines on the arteries are seen when a plus lens is placed behind the aperture, the eye is hypermetro]3ic and the strongest plus glass with which the white lines can be seen at all indicates the hypermetropia. If the white lines on the arteries cannot be seen when looking through the aperture of the ophthalmoscope nor when plus lenses are placed behind it, but do become visible when minus lenses are used, the weakest one with which they can be seen at all on the retinal vessels represents the degree of myopia. Retinal Vessels: When measuring the re- fraction of the eye, the character of the retinal vessels should be noted. If the veins are normal and the arteries are small and threadlike, there is a strong suspicion of optic atro])hv and the field should be taken. (See Plate XVllI.) If the retinal vessels are twisted or tortuous, a diagnosis of retinitis will be made. (See Plate XXL) Nerve Head: If the nerve head is higher or more hypermetro])ic than the normal ])art of the retina, a diagnosis of optic neuritis will be made. (See Plate XXI and XXII.) Optic Xekve: If the retinal vessels do not a])pear to emerge from the center of the optic nerve (Plates I and II), but seem to disap- pear abruptly at the edge of the nerve head, a diagnosis of glaucoma will be made. ( See Plate XXIII.) However, if the optic nerve appears 104 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION wliite or gray, (See Plate XVIII) a diagnosis of atrophy should not he made, until the fields of both ej^es have been taken, providing the patient has enough vision in either eye to make this pos- sible. The field should always be taken in all suspicious cases. Pigment: If patches of wliite or spots of black are seen in the fundus, their position should be noted. If they are on top of the retinal vessels. Plates V and YI, the pigment must be in the retina, but if the vessels are on top of the spots, the lesion must be in the choroid. (Plates XI and XII.) If spots are found on the temporal side of the fundus, "in the macular region" at the fovea centralis and the patient has poor vision that cannot be made normal with glasses, a diagnosis of central choroiditis will be made. (Plate XIV and XV.) Gross lesions and changes from the normal, in the shape of large pigmented, or atrophic spots often appear in any part of the fundus except the temporal side without affecting central vision. Color of Fundus : If some part of the fundus is observed that is lighter in color than other parts or is entirely without color, the normal and abnormal portion should be refracted; and, if the lighter part is more hypermetropic, the stu- dent knows that he is dealing with an exudate, a detachment of the retina or a growth. Media: If the media is clear, a differential diagnosis can readil}^ be made. If the media is SYSTEMATIC P:XAML\ATIO-\ OF THE EYE 105 not clear and the diagnosis witli the oplithahno- scope is douhtful the tension of the eye will he of great aid. If the eye has been examined in the manner described and a diagnosis cannot he made, a last hut most important step will he the taking of the field as described on ])age 8(5. Blooj) Pkessuke: To c()m])lete the examina- tion the Systolic and Diastolic blood pressure should be taken, the urine examined, and a microscopical examination of the conjunctival contents made if necessary. Amblyopia: It is only justifiable to make a diagnosis of amblyopia if a diagnosis of some other condition cannot be made. After the student has made enough systematic examinations to have the different steps fairly fixed, he Avill not have any very great difficulty in arriving at a proper diagnosis; and when a diagnosis has been made, any text book on o])h- thalmology will give the ])ro])er treatment. Diagnosis in ophthalmology is not difficult it approached in the proper manner, but it would be impossible unless the student were master of the ophthalmoscope. TENSIO^' : Before taking the tension of any eye, the patient should be requested to look down, when we pal])ate by ])lacing the ti])s of two index fingers upon the u])])er lid and gently press down as though palpating for pus in any part of the body, noting the (lifTerence, if any. in the tension of the two eyes. (Figure 37.) 106 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 37. Testing Tension of the Eyeball Taking the tension with the fingers usually suffices when the eye is very soft or hard, hut if a suspicion of an increase of tension exists, the tonometer should be used. The use of the tonometer requires delicate technique; it need not be confined to an expert, but with a little practice can be of value in the hands of any general practitioner. Before using the tonometer, the eye must be anesthetized by dropping 3 or 4 drops of a 1% solution of holocain hydrochlorate into it. Three minutes after the medicine has been instilled the patient is placed upon tlie table and instructed to look at the ceiling with both eyes. SYSTEMATIC EXAMIMATION OF THE EYE 107 The lids are kept apart with the fingers, or with Fisher's lid hooks. ( Figures :31) and 40.) The tonometer is ])laced exactly ii]3on the center ol the cornea, held straight n]), and the tension of the eye can he read from the scale on top of the instrument. (Figure 38.) The tension should he taken with one weight, then registered, and with two weights and registered, then taken again wdth three w eights. The three readings should he the same if the instrument has heen ])ro])erlv used. If the tonometer registers ahove 28, the tension is supposed to he above normal. After the three readings are registered they may be added and divided by three to get an average. The student is again reminded that the tension is only one symptom and the vision and especially the field should always be studied in connnection with glaucoma. 108 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION TEST BLOCK fcg^ Fifr. 38. Tonometer Fig. 40. Fishev's Lower Lid Hook SYSTEMATIC EXA MINATIO-N OF THE EYE 109 Fig. 41. Tonometei- and Patient 110 OPHTHALMOSCOPY. RETINOSCOPY AND REFRACTION CHAPTER YII GLAUCOMA The general practitioner can give liis glaucoma ])atients proper treatment providing he can make a diagnosis; but a diagnosis is often impossible without a working knowledge of the ophthalmo- scope. The symptoms of glaucoma are unlike those of any other disease and they are usually so well marked that a diagnosis is within the grasp of the general practitioner. If a systematic examination of the eye is made (see Page 97) it will not be difficult to make a diagnosis of glaucoma if it exists; and all that appears necessary to enable the general ])racti- tioner to make sucli a diagnosis, is to have an ophthalmoscope, a perimeter, and a tonometer and to know liow to use them. GLAUCOMA HI Clinically, glaucoma is a sini])le proposition, l)ut scientifically much is to be learned. The subject will be treated clinically in the hope that general practitioners will be able to make a diag- nosis. Only two varieties of glaucoma need be mentioned, glaucoma which is the result of some unknown cause; and glaucoma which is caused i)y some known disease, injury, or operation upon the eye ball. Sy3IPTo:ms: A patient usually over forty, complaining of some loss of vision, pain in the eyes or head, observing a picture of a rainbow around the light, should be looked u])on as a possible case of glaucoma. At this ])articular ])oint the author believes it desirable to simplify the subject by omitting tlie word glaucoma and substituting the words "Plus tension." Anv eye that has tension above normal is glaucomatous: and when tlie tension is above normal, it must be reduced in some manner because of the danger of loss of vision. Cause of Plus Texsiox: Injuries to the eye or operations upon tlie eye ball and intlamniation of the eye causing adhesions of the iris to the lens cause many eyes to become hard, or have |)lus tension: but plus tension may appear and destroy the eye without any known cause. Examination of the eye from before backward in a typical case would be as follows: Plus Tension : Cornea anesthetic and hazy : anterior chamber shallow: acqueous, cloudy, iris muddy: pupil dilated: lens clear: vitreous clear; pulsating retinal arteries; nerve head cupped. 112 OPHTHALMOSCOPY, RETLNOSCOPY AND REFRACTION (See Plates XXIIl and Figure 16.) Field contracted below and to the nasal side. (Figure •24.) All of these symptoms need not be found, but enough of tliem to establish a diagnosis can usu- ally be found in glaucoma. If the student is doubtful about any increase in tension such as is usually determined by the fingers, (Figure 37) he can measure the tension with tlie tonometer which is more dependable, es- pecially to the inexperienced, in taking the ten- sion (Figure 38) ; and, if still in doubt, the field can be taken with tlie perimeter which is all im- portant and does not require an expert. If all these precautions are taken in doubtful cases, the medical men would not make many errors in diagnosing. AVhen the condition has been diagnosed in the eye com])lained of, taking the tension and field of the other eye is impera- tive. The ])rompt institution of treatment in this inci])ient stage often arrests the progress of the disease. Prognosis: The prognosis will depend u])ou the cause, being grave, in those that have no known causation, as in Plate XXIII and XXIV, but guarded in all cases. Treatment: In those that have plus tension from injuries to or operations upon the eye ball, or inflammations that have caused adhesions of the iris to the lens, atropin sulphate is indicated, using two drops of a l^ solution dropped into the eve three times a dav; alwavs instructing the GLAUCOMA 113 ])atient to press upon the tear duct for a iiiiuute after putting in tlie drops. In those that have pkis tension from some un- known cause, the treatment is quite simple and consists of a sohition of eserin salicyhite to be dropped into the eye instead of atropin. As soon as the eye is found to liave tension above the normal without a known cause for the condition, two drops of freshly ])repared and sterile sohition of sahcylate of eserin should be instilled into the eye every three hours day and night. The medicine needs to be continued throughout the entire twenty-four hours because the effect of eserin lasts only about three hours. It is often best to begin with a solution of V2 gi'ain to the ounce. If the tension is reduced to normal with this weak solution, it can be kept up indefinitely; or a solution of nitrate of pilo- carpin, "Posey" can be substituted for the eserin to be used during the day with eserin at night. If the weak solution does not have any effect upon the tension after three instillations, the strength should be made one grain to the ounce. If this strength does not suffice with three instilla- tions, a still further hicrease can be made up to four strains to the ounce unless it causes severe pain. Eserin and Pilocarpin are both used at the same time by some with good effect. Some insist upon the patient being in bed while the myotic is being used. A general examination should be made in an endeavor to locate the cause which should include the examination of the urine, blood, mouth, throat, nose and intestinal canal 114 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION with an X-Ray of the teeth, and snch genera] treatment as is indicated, including ehminatives especially (an enema should be given every night). If the tension is not reduced, operative procedure should not be delayed. Atropin and Eserix: The student is cau- tioned regarding atropin and eserin. Eserin is used in all cases tchere the eye has plus tension mthout a knotcn cause, and atropin after in- juries to the eye, after operation upon the e^^e ball, and tchen the eye has plus tension from in- flammation where the iris is adherent to the lens. The student will see by the foregoing that eserin and atropin have their distinctive places. It is not often that a mistake is made — because of the exact indications for the use of each. Operative Treatment: When an eye is in- jured, the lens may become opaque. "Traumatic Cataract," produces swelling; and, in patients over twenty, it is often necessary to remove the lens. In such cases, atropin or eserin would not suffice because the swollen lens would be the cause of the plus tension and its removal would be the only rational method of reducing it. Occluded Pupil: Adhesions of the iris to the lens resulting from inflammation of the eye sometimes prevent the aqueous from passing from the anterior to the posterior chamber and may be so firm that they cannot be broken by the use of atropin. They may thus be the cause of the increased tension. In such a case an iridectomy should be done upward to reduce the tension without disfiguring GLAUCOMA 115 the eye, si nee the iridectomy would be covered by the lid. It is not necessary to make a deep iridectomy for this purpose as must be done for reducing tension with an unknown cause. Pakacentesls : A cataract knife is passed into the anterior chamber, turned slightly upon its edge, tlie anterior chamber slowly evacuated, the knife carefully withdrawn, and the eye bandaged. Various operative procedures have been devised for reducing the tension when the cause is not known but commonly called glaucoma; a prop- erly performed iridectomy has produced the best results in the author's hands and the Smith method has been unusuallv satisfactorv. 116 OPHTHALMOSCOPY, RETI.NOSCOPY AND REFRACTION CHAPTER VIII OPTICAL PRINCIPLES, TEST TYPE, LENSES, REFRACTION AND CYLOPEGICS Eacli of the various methods of diagnosis of refractive errors is some apphcation of the use of lenses; and the placing of them before the defective eye for more or less constant wear is the only means we have for their correction. It is therefore necessary to try to make clear the theory of their action, and their application for these purposes. Light: Light or radiant energy is given off from all luminous objects, its greatest source of course being the sun. It is transmitted by wave action in the universal ether at the enormous speed of nearly two hundred thousand miles per second through empty space where it meets with no resistance. As it approaches the earth, how- ever, its speed is slightly reduced by tlie inter- ference offered by our atmosphere and more so by other objects of greater density with which it comes in contact, and which, if at all pigmented, absorb a greater or less quantity of the light as it passes through or enters into them. The whole theory of the action of lenses rests on the above phenomena. Laws or Lens Action: In taking up the study of the action of lenses, tlie student must accept the following two laws : OPTICAL PRINCIPLES 117 1. A ray of litilit entering and leaving" a re- fracting medium ])eri)en(licular (or noi'inal as it is called in optical nomenclature) to its surface, is not refracted but continues with its direction unchanged. Such a ray is spoken of as the axial ray. 2. A ray of light entering a denser from a rarer refracting medium is deviated toward the ])erpendicular to the entered surface; and leaving a denser to reenter a rarer medium, is refracted away from the perpendicular to the surface last passed through. Practically, however, in our work the net result of this double refraction is a deviation of the refracted ray toward the thicker portion of the denser refracting medium. Pkoductiox of Images: The next point in our study of lens action is the consideration of the phenomena of the production of images which is really only an application of the two above laws, differing from the latter only in the fact of considering the action of all the incident rays instead of only a few. Action of Convex Lenses: If, in the case of the convex lens, (Figure 42) instead of only one or two incident rays, we consider tlie action of all the I'ays that enter, we can readily see that we must have such a result as is illustrated in Figure 42, in which all the incident rays are shown converging and tinally coming to a point of focus after passing tlirough the lens. This is not a matter of theory, but can be shown experimentally with any suitable source of illumi- 118 OPHTHALMOSCOPY, RETIXOSCOPY AND REFRACTION nation and a screen placed at the ])roper distance irom the lens. When the source of illumination is placed twenty feet or farther away, usually spoken of as infinity from the lens, the rays that leave it and enter the latter, do so practically parallel to each other; and, in order to secure a distant image, which will he inverted, of the source of illumina- tion, the screen must be placed at a certain defi- nite distance from the center of the lens. This point is called the principal focus of the lens and its distance from the center of the latter is the focal length. This last is made use of in com- puting the dioptric or refractive strength of the lens as described on page 127. Since the image in this case can be demonstrated as described above, it is spoken of as a positive or real image, and the point at wliich it occurs as a positive or real focus. Fig. 42. The Action of a Convex Fig. 43. The Action of a Concave Lens on Parallel Rays. (May.) Lens on Parallel Rays. (May.) AcTiox OF Concave Lenses: Figure 48. When we apply the above principles to the con- cave lens, we secure the very different result illus- trated in Figure 43. The parallel rays entering the lens are caused to diverge and obviously can never come to a OPTICAL PRINCIPLES 119 focus. However, if we place one eye in the path of these divergent rays, we are able to observe an erect reduced image of the source of illumina- tion which is the result of the prolonging back- ward of the refracted divergent rays shown by the dotted lines in Figure 43; this image is located at the priiici])al focus of the lens. Such an image which cannot be thrown on a screen and can be observed only through the concave lens producing it, is spoken of as a virtual image. Conjugate Foci : Another, but minor matter to be considered in studying the action of convex lenses is that of conjugate foci, (Figure 44) in Fig 44. ConjuKate Fc of Convex Lens. (May.) Which the source of illumination being less than twenty feet away, the incident rays enter the lens not parallel to each other but decidedly diverging. Obviously they will not be brought to a focus at a point as near the lens as they would if they had entered the latter parallel to each other. In sucli a case, the source of illumination and its image beyond tlie lens are s])oken of as con- jugate foci, and are interchangeable and capable of being located at any point between the princi- pal focus of the lens and twenty feet. The Spectru:m : There is, however, one strik 120 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION ing phenomena that oceurs when performing the above experiment which the student shonld un- derstand. If a suitable screen (a prism) be pro- vided on whicli the emergent rays are allowed to fall, instead of a colorless illumination of it oc- curring, such as happened when the convex and concave lenses were used, there will be a beautiful display of colors always in a definite order — red, orange, yellow, green, blue, indigo and violet, reading from the apex toward the base of the prism. These colors in tliis order are spoken of as the primary colors of the SOLAR SPEC- TRUM. Concave and Convex Lenses as Prisms : The above ])henomena occur in a modified degree Fig. 45. Formation of Lenses by Prisms. (May.) Fig. 46. Convex Lenses. 1, Piano-Con- vex ; 2, Bi-Convex ; 3, Convex meniscus. (May.) Fig. 47. Concave Lenses. 1, Plano-Con- Concave ; 2, Bi-Con- cave ; 3, Concave me- niscus. (May.) when strong convex or concave lenses are used, since, as shown by Figure 4.5, they may quite properly be regarded as collections of prisms with their bases toward the center or periphery of the lens as the case may be. The last point is aptly illustrated by the cus- tomarily used rapid method for determining the character of an unknown lens, looking at a OPTICAL PRINCIPLKS 121 distant object through it wliile moving the lens slight!}' from side to side, when it will be noted that the object looked at seems to move in the direction opposite to that taken by the lens if it be convex and in the same direction if it be concave. 1 Fig. 48. Refraction by Convex Cylindric Lens. (Ball.) Fig. 49. Refraction by Concave Cylindric Lens. (Ball.) CviJNDRTCAi. Lenses: There remains yet an- other form of lens to consider, which, from its shape, is called the cylindrical lens and which may be either convex or concave. It differs in shape from the other forms in, that in one direction or axis of the lens, as it is called, there is absolutely no curvature and hence, rays entering in this region undergo no refraction. On leaving the axis, however, a curvature be- 122 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION gins and gradually increases until, in the meridian at right angles to the axis, it reaches a maximum and rays passing through it are markedly re- fracted. As stated above this lens may be either convex or concave, and the phenomena of image produc- tion occurs in precisely the same way as previ- ously described save that, instead of a focal point, a focal line is produced which always extends in the same direction as does the axis of the lens. Action of Lenses in Practice : In the above discussion of the action of lenses, which will not be referred to again but which must be thor- oughly understood by the student for the purpose of emphasis and other reasons, much has been said about the focus, the focal distance, etc. In actual practice, however, in either diagnosis or treatment actual images are never produced and incident rays are never brought to a focus save in the applications of indirect ophthalmoscopy. Lenses are used rather, even on eyes from which the crystalline lens has been removed, to modify the incident rays only in an amoimt equal to the deficiency of the eye under examination or treat- ment, leaving the final focus and image to be produced bv tlie refractive svstem of the eve itself. Lens Material: A careful consideration of the above Avill make it clear that any transparent object with variously shaped surfaces may act in the capacity of a lens. It having been found that air having a refractive strength only slightly in excess of a vacuum, it has been taken as a OPTICAL PRINCIPLES 123 standard and ex]jeriments have ])een ])erfornied with many different suhstances to determine their refractive powers as compared with that of air, the results being recorded as indices of refraction. Those of the commoner ones and of the refractive mediae of the eye are given in the following table: IXDIC ES OF REFKACTIOX Air 1.00 Water 1 .33 CroAvn glass 1 ..5 Flint glass l.,58 Diamond 2 A Cornea 1.33 Aqueous humor 1.3 Crystalline lens 1.41 Vitreous liumor 1.3.5 It is obvious that of the above substances, glass is the only one that can be made use of on a conmiercial scale for the manufacture of lenses: and, of the two forms, crown glass has been found to be preferable. Flint glass is made use of only and in combination Avith crown glass in the manu- facture of optical instruments in which s])herical aberration must be overcome, and f(^r making certain forms of bifocal lenses. Test Lens and Tkiai- Fi?a:mk: Crown glass as noted above has been found to liave certain advantages over Hint that liave resulted in its coming into general use. In addition to its use in the various otiier instruments, it is made up in sets of pairs of convex and concave s])]ieres and 124 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION convex and concave cylinders varying in refrac- tive strength by suitable intervals from the weakest lens used to as strong as is usually re- quired, mounted in circular frame in the handle of which is cut a plus or minus sign to indicate the character of the contained lens, and on which is also stamped its dioptric value, of one and one- half inch, or one and one-fourth inch, of which the former has been found to be the ])referable. Fig. 50. Trial Frame The trial frame should have a quadrant at- tached to each cell which shoidd be capable of various adjustments in order that the lenses may be properly centered before the eyes and that it with its weight, which is necessarily considerable, may be comfortably worn. (See Figure 50.) Various substitutes have been devised to over- come the objection to the weight of the trial frame, which occasions considerable difficulty. Cyhndrical lenses are further distinguished by having a short line etched at tlie extremities of the meridian of the axis, and sometimes in addi- OPTICA I. PRINCIPLES 125 FiK. r.l. Maddux Rod tion to the above a frosting- of the borders of the lens parallel to the axis. Some operators prefer a further general differentiation between tlie plus and minus lenses having the frames of the two forms made of different materials, as for instance, ahiminic for tlie ])his and gold phited for the minus. 126 OPHTHALMOSCOPY. RETINOSCOPY AND REFRACTION Accessories and Pris:ms: In addition to the spheres and cyhnders described above certain accessory discs, the uses of which will be discussed later, are provided, as well as a set of prisms with their strengths usually expressed in prism diop- tres stamped on the handle. A prism dioptre is described as the amount of prismatic effect produced by decentering a one dioptre sphere one centimeter in any direction or a one dioptre cylinder a similar distance in the direction at right angles to its axis. Fig. 55. Ti-ial Case The Trial Case: For convenience sake all of the above are collected in sets and kept in suitable containers w^hich are made in various forms to suit the needs of the operator; of these the most common form is shown in figure 55 and the whole collection with the containers is known as the trial case. In determining the refractive condition of an eye by the so called subjective method, the patient w^th the trial frame properly adjusted looks at OPTICAL PRINCIPLES 127 some object selected by the operator and reports to the latter the effects on vision produced by the introduction into the trial frame of various lenses or accessories from the trial case, the successive changes being determined by the effects pro- duced. With the many workers in the same field it has, of course, been found desirable to have a standard of tests objects, as they are called. For distant testing, Snellen's test type with its vari- ous adaptions for the examination of illiterates is the one used. As was stated in the discussion of lens action, after having traveled a distance of twenty feet from their source or origin, rays of light are practically ])arallel. For accurate work this distance should be maintained either actually or by the use of a reversed chart and a mirror between the ])atient and the test type, in all dis- tant subjective examination. Snellen's Test Types: The final application of the Snellen principle is the production of a chart such as is shown in Figures 06, .57 and .58, consisting of letters of such different sizes that, conforming to the above principle and wlien well illuminated, tlie various lines should be read by the individual with normal vision at distances ranging from ten to two hundred feet. The Illiterate Chart: Various modifica- tions of this chart have been devised but the most useful one and the only other one the operator need have is the "E" chart, (Figure 57) for use with those who do not read Englisli and for children who when provided with the metal "E," (Figure 59) become very much 128 OPHTHALMOSCOPY, RETINOSCOPY .AND REFRACTION Jfc, E . a F P-2 ■E , s q; n -T O Z-3 n E 2 e-S T- - p E c r D?: 5 3 u m 3 S :-a 1 a oaToiTota ^ . . , » , , .^. 9 G .^. . , a , , . .„ -. r . , . T . . . y 10 ^ ,..11 0L_. ,,,,.,,, ^„ rr._, F:g. 56. Snellen Test Fig. 57. Snellen Test Fig. 58. Snellen Test Type. Type — Illiterate. Type — Reversed for Mirror. interested in indicating the letters called to their attention giving more accurate answers than when one of the numerous toy charts are used. Special Charts: Some operators claim there is an advantage in having the colors reversed, that is white letters on a black background, and a recent investigator has presented evidence to show that red letters on a white background give more accurate results. The Reversed Chart: Should it happen that the operator is working in an office of con- OPTICAL PKIXCIPLES 129 Fig. 59. Metal "E" with Handle siderably less tlian twenty feet length, he will need to make use of a reversed Snellen chart. (Figure .58) hung in a good light above the patient's head and a mirror placed ten feet away whicli doubles the distance. If this distance does not corres])ond with the end of the room, the mirror may be hung on a bracket so tliat it may be swung out into ])osition as needed and back against the wall wlien not in use. With this arrangement, one can ])oint out letters on the chart without leaving the patient's side — really a great convenience. Testing and Kkcording Visuai, x\cuity: Of course, no operatoi- refracts patients with the chart of a distance of two hundred feet, but it is found convenient to have type that should be read up to that distance as a means of recording 130 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION visual acuity. Thus, if when seated at a distance of twenty feet from the chart the patient reads the hues that should be read at that distance, his visual acuity is described as 20/20 or normal. Xot infrequently persons are met with who have better than the normal visual acuity — 20/15 or even 20/10, while in practice we constantly meet people with a vision of 20/200 or even less, in which last event we bring the chart nearer the patient until the largest type can be read, when we record his vision with a fraction making two hundred the denominator, and the distance at which the largest type was read the numerator; as for instance, if he read the 20/200 line at 8 feet we record his vision 8/200. In cases of very low acuity of vision, we note the distance at which the patient can count the operator's fingers in a good light and against a dark background, re- cording the result as "counts fingers at three feet" or 3/200, when still further reduced, we record the vision as "has perception and projection," and no vision being present, "has no perception or projection," perception meaning simply sen- sitiveness to light and projection the ability to determine from what direction it comes. Jaeger's Test Type : . For testing and record- ing the near vision and in its correction when necessary Jaeger's test type, which consists of different sizes of ordinary Roman types arranged in order of size and numbered, beginning Avitli the finest as Jaeger one (abbreviated J. 1. etc.) Figure 60 is used. OPTICAL PRINCIPLES 131 which he Mrved. Both ntasei Ihe crown, althoueh each, perhaps, the sequel, a Bata> been the inevitable for Classiciu was but the prototype of Anjou, u Brinno of Brederode, and neither was destined, in this world, to see his sacri- fices cro^roed with success. Fig. 60, Jaeger Test Type Fig. 61. Astigmatic Chart Of recent years, a new system of nuniberint^ the Jae<>'er type lias come into use, the apphca- tion of which will he (hscussed under presbyopia. The xVsTiGMATic Chart: In addition to the above charts anotlier, tlie so-called astigmatic chart, has been devised of which many forms are in use, the commonest one perhaps hein^- illus- trated in FioTire 61. While some operatoi's consider its use indis- ])ensable in the coi'rectiou of astioniatism. others prefei' to dis])eiisc with it and to (le])end on visual results, as determined with the Snellen type, alone in their work with the trial case. 132 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The Use of the Trial Case: When one is familiar witli lenses and their action, he is ready to consider their application in the diagnosis of refractive errors. The nse of the trial case and the test charts for this pm-pose is often spoken of as manifesting or taking the manifest since it is most frequently done without the ciliary muscle having been put at rest. If this latter has been done, we speak of refracting under a cyclopegic or taking the static refraction subjectively. Rules: In either event, accurate results are dependent upon a systematic use of the test lenses and accessories, the rules for which must be learned and followed, and which will now be set forth: 1st. The patient must be comfortably seated twenty feet from the well-illuminated Snellen chart with the trial frame adjusted so as to be comfortable and with the centers of the lens cells before the pupils of his eyes. 2nd. The left eye being covered witli the blank disc Figure .51, note and record the acuity of vision of the right eye. 3rd. Xow insert in the trial frame a +..50 D. sphere. If improvement occur, or if there be no impairment, gradually increase the plus until the addition of a +.25 sphere causes an impair- ment of the best vision thus far secured. 4th. Having secured all the improvement possible- with plus spheres, or, if they liave been rejected, and with the sphere in position if used, insert a + .50 D. cvlinder with the axis at various OPTICAL PRINCIPLES 13:^) positions; and, if improvement occurs at any point in the rotation, select the point of greatest improvement as tlie proper position for the axis and increase the strength of the cyh'nder so long as there is improvement. Put on all tJic pluH sphere or cijlinder, that the patient icill aeei'pt zcithout blurviug tlie smallest letters he ean read. .5th. If plus s])heres and cylinders have heen rejected, exhihit a — ..50 D. sphere, and, if im- provement occurs, increase cautiously as long as improvement occurs taking care not to over correct, (a very easy thing to do when minus lenses are accepted) because with many people greater acuity of vision is secured when the accommodation is brought slightly into play. 6th. If minus spheres have not produced a visual acuity equal to that obtained with the pin hole, exhibit a — ..50 D. cylinder with its axis at various positions; and, if improvement occurs at any position, select the ])oint of greatest improve- ment as the proper position for the axis and increase the strength of the cylinder cautiously as long as im])rovement occurs taking care not to over correct. USE AS LITTLE MLXrS SPIIENL OH (YLIXimU AS POSSIBLE 7th. Crossed Cylinders: If an improvement. ])ut not normal vision or vision ecjual to that obtained with the ])in hole, has been secured with a plus cylinder, try the cautious exliibition of 134 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION minus cylinders in combination with the plus with the axis at right angles to that of the latter. 8th. When normal vision has not been se- cured with lenses insert the pin hole disc ( Figure 52) and note if there be furtlier improvement, in which event, it will usually be possible to secure an equal vision Avith lenses. 9th. Do not hurr}^ or be peremptory with a patient; while it is inadvisable to ask leading questions, patience and tact while using the trial case will usually be repaid by greater accuracy of results. Fogging: The so called fogging system con- sists in placing a 4- 6.D. in front of the eye under examination, producing a strong artificial myopia with a great reduction of vision. A — l.D. is placed in front of the + 6.D., then a — 2.D. and so on down until the best vision is produced by the minus glass. If a ision is then abnormal, a minus cylinder is placed in front of the minus sphere turning the cylinder in the trial frame until the clearest axis is found, and adding cylinders at this axis until the best vision is obtained. The minus glass is not re- moved from the + 6.D. until the next stronger minus glass is in place. The fogging method, building down from a + 6.D. gives the same prescription or result to the author as building up with weak + glasses described on page 132. The following illustrations from Dr. Carl Wagner of Chicago, gives a good description of the fogging system. (Pages 188-153.) OPTICAL PRINCIPLES 135 Fig. A. Fig. B. Emmetropia Myopia Hyperopia Myopic Astigmatism Hyperopic Astigmi- tism Compound Myopic Astigmatism Compound Hyperopic Astigmatism Mixed Astigmatisi Posterior Anterior Posterior Retina 136 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. A (62) shows the foci of the various errors of refraction, and their relative position to the Retina. Fig. B ( 62 ) sliows the position of the foci after a + 6.D. spli. lias been placed in front of eacli error. Figures 68 and ()4 show Hyperopic and ^Myopic Astigmatism. Assuming the amount of error in both in- stances to be 2.D., and the best obtainable vi- sion to be 20 40, we may, in each case, through the use of a + 6 D. sphere, bring the focus far in front of the fundus, the resulting vision then being much below 20/40. In order to regain this 20/40 in Figure 63, it is necessary to reduce the -\- 6 D. sphere, by the gradual application of weaker lenses, and it will invariably be found that this is finally accomplished through the use of a -)- 2 D. sphere, when both foci will be in position as in Figure 64. In order to obtain 20/40 in Figure 64, we fur- ther reduce the strength of the lenses, until is reached, at which time with no lens in the trial frame, the foci would again be in the same rela- tive position as the}^ were. Fiff. 63 OPTICAL PRINCIPLKS 137 In correcting tlie astigmatism, an attempt must be made, through the use of spherical lenses, to obtain as good or better vision tlian that which exists in tlie un- aided eye. When the result is obtained, it becomes the key to further ])roced- ure. I^eaving the ac- com})hshing lens in the trial frame, minus cyl- inder lenses are now used to complete the astigmatic correction. Fipr. 64. 138 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Experimental Correction of a Normal Eye. (EMMETROPIA. ) Fig. 65 + 400 Fig. 61 Fig. +3.50 Fig. 69. Fig. 70. OPTICAL PRI.NCIPLKS 139 Experimental Collection of a Normal FZye. ( Emmetropia. ) + 2.50 ^ \ -1-2°'^ ~ Fig. 71 + ).50 Fig. 73 Fi!?. 74 +.50 PLANO Fig. ?■ Fig. 76 140 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The Correction of Hypermetropia. Fig. 78. -f- 6. ■1-5.50 Fig. 79. Fig. 80. + 5. Fig. 81. -f 4.50 Fig. 82. OPTICAL PRINCIPLES 141 Tho Coviecticn of Hypeimetio)) + 4.00 4 3^50 Fig. 83 Fijf. 81 + 3.00 + 2.75 Fit'. So Fi.'. ^tj +2J50 Fit'. 87 Fig. 88 142 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The Correction of Myopia. Fig. 89. Fig. 90. Fig. 91. PLANO Fig. 93. Fig. 94. OPTICAL PRINCIPLES 143 Fig. 95 1.^=^ Fig Fig. 98 -1.75 Fig. 99 Fig. 100 144 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION The Correction of Simple Myopic Astigmatism. NO LENS Fig. 102 Fig. 103. Fig. 104. + 3. Fig. 105. Fig. 106. OPTICAL PRINCIPLES 145 The Correction of Simple Myopic Asli)j:matism. "'" ^ ^ PLANO Fig. 101 Fig. 108 -1.^X180 Fig. IK •1-50^X180 -2^X180 Fig. Ill Fig. 11: 146 OPHTHALMOSCOPY. RETLXOSCOPY AND REFRACTION The Correction of Simple Hypermetropic Astigmatism. 4-6. Fig. ll:i. Fig:. 114. + 5. X 3:2 + 4. Fig. 115. Fig. 116. +3.0 - 1.<^X 180 Fig. 117. Fig. lis. OPTICAL PRINCIPLES 147 The Correction of Simple Hypermetropic Astigmatisrr -f-3.C-J50^X 180 +3.0— I'XISO Fig. 119 Fig. 120 + 3C— 1.50'X180 ^■3.o — Z.75 ^X ISO Fiyr. 1 -f-3.o-3"X 180 4-3. ^X 90 Fig. 123 Fig. 124 148 OPHTHALMOSCOPY. RETINOSCOPY AND REFRACTION The Correction of Compound Myopic Astigmatism. ^ 6 Fig. 125. Fig. 125. Fig. 127, Fig. I: tl. NO LEN5 Fig. 129. Fig. 130. OPTICAL PRINCIPLES 149 FiK. 131 FiK. 1^2 KKDKE TO — 1. Ib'O Fig. 133 •1C-50^X180 Fig. 134 -1.- -75^X180 Fig. 135 -l.c-l'X ISO Fig. 13t; 150 OPHTHALMOSCOPY. RETLXOSCOPY AND REFRACTION The Correction of Compound Hypermetropic Astigmatism. Fig. 137. Fig. 138. Fig. 139. Fig. 140. + 3. + 1.50 Fig. 141. Fig. 142. OPTICAL PRINCIPLES 151 The Correction of Compound Hy;.ton. (Figure 18-2.) This de\ ice is a hlack disc with a central apertui-e the si/e oF a dilated ])n|)il and an arrow ])oint on each side oF it. It is placed in the trial frame and rotated until the arrow points coincide with tlie line of movement of tlie reflex, of the long axis of the hand of light, when they will ])oint to one of the i)rinci])al meridians on the graduated arc, the other merid- ian heing 90° from this. THE POIXT OF REVERSAL This is the objective point aimed at in retinos- copy. It is the point in front of the eye where emergent rays of light meet or cross, and at this point there Avill he no movement of the reflex. We establish an artificial point of reversal at which we aim to bring emergent rays of light to a meeting ])oint or focus. This standard ])oint is one meter, and as long as emergent rays do not cross between this ])oint and the patient's eye, the movement of tlie light reflex is with, and we must place plus lenses in front of the eye until 194 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTIOy they are brought to a focus at one meter. ( See Figs. 183 and 184.) If on the other hand emergent rays of hght cross before they get to our eye, the movement oi the reflex Avill be against, and we must put minus lenses in front of the eye until they are brought to a focus, at one meter. ( See Fig. 185. ) When this point is found there will be no movement of the light reflex in the pu])il. This is the ])oint of reversal, and the lens bringing the rays to a focus at this point represents the refraction of the eye, Avith — 1 D. added, because of our es- tablishing an artificial myopic far point at 1 meter; or practically, we have rendered the eye 1 D. myopic by working at this distance. If we w^orked at one-half meter, then we would render the eye 2 D. myopic and would add — 2D. After getting the foregoing well fixed in mind, the student should practice observing the reflex and its movement in the schematic eye with the- sliding tube in different positions. APPLICATION OF RETINOSCOPY For accurate retinoscopy, the accommodation of the patient's eye must be suspended. This means that in cases where asthenopia is marked cyclopegia is necessary. When asthenopia is not marked or wliere accommodation is naturally sus- pended simple mydriasis is all that is necessary and this is only for the purpose of getting a large enough pupil so as to get contrasting light and shadow. RETINOSCOPY 195 1 METER Fig. 183. Emmetropia. (Nugent.) EMMKTROPIA 111 this condition we will find the reflex moving with the mirror and plus lenses must he put in front of tlie eye until there is no movement. A + 1 D. lens will give u]) a ])oint of no movement, nnd adding our — 1 D. lens for the one meter distance, we have or emmetro])ia as the result. (Fig. 188.) 1 METER Fig. 184. Hypermetropia. (Nugent. HYPKRMETROPIA Here again we will find the reflex moving with the mirror, and plus lenses must he placed in front of the eye to hring the rays of light to a focus at our position of one meter. AMien we have the plus lens that gives no movement of the reflex, we have estahlished the ])oint of reversal: and if we aet the same result in hotli the vertical 196 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION and horizontal meridians, we have a simple hy- permetropia. The true amount of error, ho^vever, ^vill l)e represented hy tlie strength of the ])lus lens found with — ^ 1 D. added, i. e., in a given case it takes a + ^ I^- to give the point of reversal in hoth meridians, adding — 1 D. the result is -f- 8 D., which will be our starting point at the trial case. 1 METER Fig. 185. Myopia. (Nugent.) MYOPIA In this we find the reflex moving with the mirror in myopia of less than 1 D. because emergent rays cross beyond one meter, and less than + 1 D. will give us the point of reversal. The addition of — 1 D. then gives less than — 1 D. as the resulting myopia, i. e., + ..50 I). gives point of reversal in both meridians, adding — 1 D., the result is — ..50 D. In myopia of more than 1 D. the reflex will alwaj^s move against the mirror, and we must put — lenses in front of the patient's eye to bring the rays of light to a focus at one meter. The glass which gives no movement of the reflex es- tablishes the point of reversal; and if we get the RETINOSCOPY 197 same result in both the vertical and horizontal meridians, we have a sim])le mvo])ia. ( Figure 185.) The true amount of tlie error, however, will be represented by the strength of the — lens with — 1 D. added, i. e., in a given case it takes a — *i D. to give the ])oint of reversal in both merid- ians: adding — 1 D. the result is — 4 D. which will be our starting point at the trial case. APPLICATIOX OF KETIXOSCOPY ASTIGMATISM In tliis condition we will find the reflex assum- ing an elongated or band like appearance reach- ing across the pupillary area, the long axis of the elongated reflex or band being in the meridian of least error and indicating the direction in which tlie axis of the correcting cylinder should be i^laced. For ])ractice with the schematic eye, an astigmatism can be pro- duced showing tlie band of liglit by placing a cylinder in the slot ]jrovided for lenses on the front end of tile model. Tlie student must remember that when lie uses a plus cylinder he is ])ro- ducing myopic astigmatism, and when a minus cylinder, hy])ermetropic astig- matism. Cylinders from .7,5 D. to 1..50 D. give best banded reflect wlien used on a scliematic eve. (Figure 186.) Fig. 186. Retinoscop- ic illumination and shadow in AstiRma- tism. (May.) 198 OPHTHALMOSCOPY, RETli\OSCOPY AND REFRACTION SIMPLE HYPERMETROPIC ASTIGMATISM The reflex will move with in hoth meridians and the banded appearance will be seen early. The meridian in which the long axis lies will be corrected with a + 1 I^- lens, indicating em- metropia. The other meridian will be corrected with a stronger -j- lens and the + lens giving the point for that meridian Avith — 1 D. added will indicate the amount of astigmatism. (Figure 187.) This result will be the starting point at the trial case, i. e., a -)- cylinder with the axis in the emmetropic meridian. +1D +2D Fig. 187. Simple Hypermetrcpic Astigmatism. (Nugent.) + 1.00 D., in weak meridian + 2.00 D. in strong meridian, adding — 1.00 D. will give in weaker meridian, indicating emmetropia. — 1 D. added to stronger meridian gives + 1.00 D. which requires a + 1-00 D. cylinder axis 90' or in weaker meridian indicated by the band of light. RETINOSCOPY 199 + 2D Fig. 188. Compound hypermetropic astigmatism as reflex appears be- fore neutralizing lenses are used. (Nugent.) + 3D Fig. 189. Compound hypermetropic astigmatism as reflex appears after the weak meridian has been neu- tralized. (Nugent.) COMPOUND HYPERMETROPIC ASTIGMATISM (Fig. 188 and 189) Here the reflex moves in both meridians, but slower in one than in the other. The band of light may not appear until the weaker or faster moving meridian is corrected or nearly so. The result will be a stronger tlian + 1 D. lens in this meridian, and a stronger one still for the slower moving meridian, i. e., weak meridian + 2 D. strong meridian + 3 D. adding — 1 1). will give a + 1 D. for the weaker and a + 1 D. sphere with a + 1 1). cylinder with its axis in the weaker meridian or + 1.00 + 1.00 ax 90^. (See Xugent's Rule.) Fig. U Geneva Ophthalmoscope and Retinoscope (descriptive pamphlet accompanies the instrument). 200 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION +1.00 FiK. l'.*0. Simple Myopic Astigma- tism of more than 1 D. (Nugent.) +1.50 Fig. 191. Simple Hypermetropic Astigmatism of less than 1 D. (Nugent.) SIMPLE MYOPIC ASTIGMATISM If the astigmatism is more tlian 1 D. we Avill find the reflex moving with the mirror in one meridian and a -f 1 D. lens will give the point or reversal; adding — 1 D. gives emmetropia for that meridian. The opposite meridian, how- ever, will give an against the mirror movement of the reflex and it Avill take a minus lens to give the point of reversal, and adding a — 1 D. will give one more dioptre of myopia for that merid- ian. This lens, a cylinder with tlie axis in the emmetropic meridian, will be our starting point at the trial case. If the myopic meridian is less than 1 D. the motion of the reflex will be with the mirror; the point of reversal will be indicated by a + lens of less than 1 D. and the result will be estimated the same as in myopia, but in one meridian at a time. (Figure 191.) COMPOUND MYOPIC ASTIGMATISM If the myopia is more than 1.00 D. the reflex will move against the mirror in both meridians, but at different rates. The more rapidly moving KTINOSCOPY 201 -2D I'i.LC. 1'.*:^. Compound myopic astiK- matism showinK appearance of re- flex before neulralizinR lens is used. (Nugent.) -ID Fig. 193. Compound myopic astig- matism showing appearance of band of light after meridian of least error has been neutralized. 2 D Sph. — ID cyl. X 180. See Nu- gent's Rule, Paare 202. reflex will be in the meridian of least error and the more slowly moving reflex will be in the one of greatest error. Estimating each meridian sep- arately, and adding — 1 D. for our distance of 1 meter, as in all other cases, we have as a result a minus sphere combined with a minus cylinder with its axis in the weaker meridian. Figures 192 and 193. MIXED ASTIGMATISM In this condition we will find the two meridians indicating different denominations of refraction, — ^i. e. myopia in one and hyperopia in the other. Each meridian should be estimated se])arately and — 1 I), be added to the correction found for each meridian. Figs. 184 and 185. The coi-- recting lens obtained by combining the two lenses iiito one is called a crossed cylinder, and the axes of these cylinders are 90 apart or at right angles. Crossed cylinder, however, is not often used, the correction being made by a combination of a s])here and cylinder. See Xugent's Kule. 202 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION IRREGULAR ASTIGMATISM Retinoscopy does not give very satisfactory results in this condition. It is usually caused by opacities on the cornea or lens, and these so scatter the rays of light that no distinct direction of movement can be made out. However, by persistence a result may be obtained which is useful as a foundation in getting a manifest cor- rection that will be beneficial to the patient. LENSES USED In estimating the refraction by retinoscopy the lenses actually necessary are spheres only, as we estimate first one meridian, then the other. Some refractionists, however, prefer to use cylinders in the estimation of astigmatism. This is un- necessary and is apt to be confusing because of the many surfaces for reflections of light. Nugent's Rule: The following rule devised by Dr. O. B. Xugent for the purpose of writing formulae from net retinoscopic findings, is con- cise, accurate, easy to understand and memorize, and is applicable to each and all of the results obtained by the retinoscope. The Rule: Choose the numeral from one (lesser) meridian for the sphere. Xow subtract this number from the numeral in the other (greater) meridian. The remainder is the strength and sign of the cylinder, the axis of which is indicated by the meridian from which sph. was chosen. (Figure 194.) RETINOSCOPY 203 +2 sph. +2 +2 +2 no cyl. +2 +1 sph. + 2 + 1 + 1= + 1x90 -2 + 1 +2 +2- -1 X 180 -2 sph. +3 -2 —^ 2 +5x90 +3 -2 +3 +3 —5 x 180 Fig. 194. Nugent's Rule PRACTICAL WAY OF IIXDIXG THE POIXT OF REVERSAL It has been found tliat, as the point of no move- ment of the refiex is hard to recognize and is generally ambiguous, the most practical way of finding the point of reversal is to take the half- way point between the strongest lens with which the reflex distinctly moves in the same direction and the weakest lens with which it distinctly moves in the opposite direction, i. e. in a given case the reflex moves without a lens, and tlie strongest lens with which it moves distinctly with is a -r 4 13., the weakest with which it moves dis- tinctly against is a + 4.. .50 D., or the half-way 204 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION point between the two is + -4.25 D., or the point of reversal. Again, if the reflex without lenses moves against, and the strongest lense with wliich it moves against is a — 5 D., and the weakest with which it moves with is a — 5. 50 D., then the half-way point between them is — .5.2.5 D. or the point of reversal. SPHERIC ABERRATION This is a condition that often puzzles the be- ginner. Because of the widely dilated pupil, there are two distinct areas of light and shadow, a peripheral one and a central one. In positive aberration the central reflex moves with, and the peripheral area of light or shadow, against the mirror. In negative aberration, (conic cornea) the central reflex moves against and the peripheral one with the mirror. If the student will get in the habit of always observing the movement of the reflex throughout a four to five millimeter area at the apex of the cornea he will not be bothered by these con- ditions. We do not care for the refraction in the periphery as this area is covered by the iris, hence, we disregard it. Spheric aberration is frequently annoying in estimating astigmatism in the vertical meridian. As in astigmatism the reflex is banded, we find in this condition a band of light running horizon- tally across the pupil, with the ends of the ring obliterated by the iris. This gives us the appear- RETINOSCOPY 205 aiice of three bands; and when the eye is tilted shghtly np or down, one of the bands is not seen, and we find only two bands which come together and separate like the blades of a pair of scissors as we tilt the mirror vertically. The condition is called the scissors movement, and is sometimes ascribed as l)eing due to a tilting of the lens in its fossa. This gives another reason why we should stick to the central reflex. The lens used to correct this error with the retinoscope is one that will keep the two "bands of light" together, or nearly so. VALUE OF RETIXOSCOPY The value of retinoscopy is in tiie fact that it is a method by which we get the refraction of the eye objectively. This makes it indispensable in young (Hypermetropic) children, with stra- bismus or other condition where glasses are nec- essary, and illiterates from any cause, who cannot tell us wliat lenses they see best witli at tlie trial case. MVDKIATKS AND C VC LOPEGR'S For many cases of refraction, the use of drugs is necessary for dilating the pupil and suspending the accommodation and we should have a clear idea in our minds as to what we can ex])ect from those drugs and how to use them. A mydriatic is a drug which dilates the pupil. A cyclo])egic not only dilates the pu])il but paralyzes the ciliary muscle. 206 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION All cyclopegics are mydriatics, but all my- driatics are not cyclopegics. The following table gives the different my- driatics and cyclopegics with duration of the paralysis : Euphthalmin — purely mydriatic. Cocoain — purely mydriatic. Occasionally slightly cyclopegic. Homatropin — complete ])aralysis — 2 liours ; complete recovery 2 days. Scopolamin — complete paralysis — ^o hour; complete recovery 4 days. Hyoscyamin — complete ]jaralysis, 3 days; complete recovery 8 days. Duboisin — complete paralysis, 2 days; com- plete recovery 8 days. Atropin — complete paralysis, 2 days ; complete recovery 1.5 days. Solution of proper strength of those drugs A\hen dropped into the eye, in a short time begins to give effect, by acting on the nerve endings of the sphincter muscles of the iris and ciliary body, paralyzing their action, thus producing dilated pupil and suspension of accommodation. Atropin, is the most reliable cyclopegic, and where accurate suspension of accommodation is desired should be used. It is used in solutions varying from two to ten grains to the ounce. The two grains solution for children up to the age of ten years and the four grains solution from this age upward. The stronger solution is gener- ally used only where the weaker solution has failed to give complete cyclopegia. RETINOSCOPY 207 There is very little danger of getting toxic effects from the drug, if care is used in closing the puncta by pressure over the inner canthi with the thumb and finger dee])ly enough to close the canaliculi and instilling the solution (not drop- ping it) into the eye at the external canthi. In this way the solution is kept from getting into the throat, through the nasal ducts, swallowed, and taken up by the stomach. The symptoms of poisoning are dry throat, flushed face, and rapid pulse, and when they occur the drug should be discontinued. The action of this drug while profound is slow, and it should be dropped into the eyes three or four times a day for three days, when the cyclopegia is usually complete, and the patient ready for refraction. If the cyclopegia is not complete, it can be used for a day or two longer. In fact, when the patient is using atropine, we might as well use it long enough to get two examinations approximating each other pretty closely, when we can feel certain we have obtained the best result. Homatropin, is the most transient cvclopegic we have and is very useful in the examination of adults, (and even good results can be secured in children) where time cannot be given to the use of atropin. For use in the office we are ac- customed to use the Xo. 842 gelatin disc of Wyeth. It is used also in 2 per-cent solution in water or oil (castor or olive) one drop being instilled into the conjunctival sac every five minutes six 208 OPHTHALMOSCOPY, RETINOSCOPY AND REFKACTiON to eight times when, after twenty to thirty minutes, the action is supposed to be complete and the patient ready for refraction. The practical way to use the discs is to pick- up one witli a pledget of cotton, wound on a toothpick or probe and, dampened with boric acid solution or sterile water, and ])lace it in the lower conjinictival sac. If the cotton is quite wet the disc will readily adhere to the conjunctiva. Let the patient keep his eyes closed for half an hour (best by bandaging), use a separate disc in each eye, and keep the eyes closed again; action will be obtained in one hour from the time first disc is used. Some ])refer to use a disc every twenty minutes for three times, Avaiting twenty minutes after tlie last one when the patient is ready for refraction. Scopolamin is quite a favorite with some ocu- lists, but its action in our experience is no better than homatropin and the effect is more prolonged. It is advised to use it in a one grain to the ounce solution, one drop of which solution instilled into the conjunctival sac is supposed to give complete cyclopegia in one-half hour. Hyoscyamin is not often used. Duboisin is useful more as a substitute for atropin, when there seems to be an idiosyncrasy for the latter drug. This is manifested by a marked conjimctival irritation with" erythema. Duboisin is" best used in a 1 per cent ointment. LENSES — PRESCRIPTIONS — FRAME FITTING 209 CHAPTKK XII .MKASIKKMKXT OF I.KXSKS, PKK- SClill^TIOX WlilTIXC;, TKAXSPO- SITIOX AXD 1 llA.^IK 1 Ti TIXG The determination of the ])roper correetion is not nearly all that is necessary in tlie treatment of refractive errors; hut, if success in this im- portant branch of therapeutics is to he attained, as much care must he taken in selecting tlie form of lens suited to the case and in ])roperly mount- ing it before the eye as is used in doing the refrac- tion. Foinrs of Lkxses: In the early days of tlie s])ecialty, s])]ierical lenses were either biconvex or biconcave as tlie case might be, as shown iij Figures 19.5 and 196. Fig. 195. Convex Lenses. 1, Piano- Convex ; 2, Bi-Convex ; 3. Convex Meniscus. (May.) FiK. lite. Concave Lenses. 1. Plano- concave : 2, Bi-Concave ; 3, Con- cave Meniscus. (May.) For cosmetic reasons and for the purpose of bringing the periphery of the lens nearer the eye the piano convex and concave, ( Figures 19,5 and 196) were devised. The meniscus form, even with only the usual ])lus or minus one and twenty- 210 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION five hundreths D. base surface has been found so much more satisfactory than the earlier forms that of recent years much deeper meniscus forms, six dioptre base surface or even in some cases nine dioptre base surface have come into general use. This form has been found to be comparatively free from annoying reflections, to bring the edge of the lens quite near the eye and to have the added advantage of causing the eye to look more learly at right angles to its surface. ToRic Lexs: The deep meniscus lens has proven so satisfactory that there has been de- veloped a demand for a similar lens in cylindrical correction which has been met by the toric lens. By varying the radii of curvature any desired difference of refractive power between the two meridians, the cylindrical correction may be produced. Then by grinding a neutralizing sphere on the original plane surface, the spheri- cal correction will result. Example: If it is desired to make a + 1 D. sph. C -\- 1 cjd. ax 90 in the toric form, a blank is selected in which the meridian of least curva- ture, called the case curve, has a refractive power of 6 D and the stronger one has the refractive power of + 7 D. Remembering that the dioptric power of a lens is equal to the algebraic sum of the two surfaces expressed dioptrically, we now grind a minus 50 sphere on the plane surface pro- ducing the desired strength, and cut the lens from the blank with its weakest meridian at 90°. TRANSPOSITION OF LENSES 211 Theoretically, a toric lens need not be of the deep meniscns form, but practically they always are so, because the sole purpose for which they are made is to obtain the advantat^es resulting from the meniscus form. Transposition of Lenses: While in prac- tice, when prescribing toric lenses, it is safer for the oculist to leave the above calculations to the optician; it is necessary that he have a thorough knowledge of transposition, the combining of two lenses into one or of changing the form of a lens to a more desirable one while retaining the same dioptric power. RuEEs FOR Transposing: Rule 1. To com- bine plus spheres and cylinders or minus spheres and cylinders to produce a periscopic lens, take the sum of the sphere and cylinder for the new sphere and retain the cylinder with its sign changed and axis moved 90 degrees. Examples: 1. + 1 C + 1 cyl. ax. 10.5 = + 2 sph. Z — 1 ax. 1,5. 2.-2 sph. I — - .50 cyl. ax. 180 — — 2.50 sph. I + 50 cyl. ax. 90. Rule 2. To combine spheres and cylinders of opposite signs, take their numerical difference for the new sphere giving it the sign of the stronger original lens and retain the cylinder changing its sign and moving its axis 90 degrees. Examples: 1. + 3 sph. C — 2 cyl. ax. 90 = + 1 sph. r_+ 2 cyi. ax. 180: 2. -f .50 sph. _ — 2.50 cyl. ax. 150 = — 2 sph. ^ + 2.50 cyl. ax. 60 ; 212 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION 3. — 8 sph. r + 3 cyl. ax. 100 = + 2.00 sph. _ — 1 cyl. ax. 10; 4. — 1 sph. Z + 3 cyl. ax. 100 =- + 2.00 sph. Z —3 cyl. ax. 10. Rule 3. To convert cylinders, either plus or minus, to sphere cylinders, use sphere of same power and sign and retain cylinder with sign changed and axis moved 90 degrees. Examples: 1. + 2.25 cyl. ax. 90 Z + 2.25 sph. = — 2.25 cvl. ax. 180. 2. — 1.75 cvl. ax. 180 Z — 1.75 sph. = + 1.75 cyl. ax. 90. Rule 4. To change crossed cylinders of like sign to sphere cylinders, take the weaker cylinder for the sphere retaining its sign and the differ- ence between the original cylinders for the new numerical cylinders retaining the sign and axis of the stronger. Examples: 1. + 1 cyl. ax. lOJ) 1+2 cyl. ax. 10 = + 1 sph. I + 1 cyl. ax. 10; 2.-2 cyl. ax. 170 _ — I'cyl. ax. 80 = — 1 sph. r — 1 cyl. ax. 170. or, take stronger cylinder for sphere retaining its sign and the numerical difference between the original cylinders for the new cylinder, changing the sign and giving it the axis of the stronger one. Examples: 1. +2.00 cyl. ax. 180 I^+ 3 cyl. ax. 90 ='+ 3.00 sph. Z — 1 cyl. ax. 180; 2. — 3.00 cyl. ax. 180 C — 2 cyl. ax. 90 ='— 3.00 sph. C + 1 cyl. ax. 180. Rule 5. To change crossed cylinders of unlike TRANSPOSITION OF LENSES 213 sign to sphere-cylinders : Take either cyhnder for the sphere retaining its sign and the algehraic sum of hoth cylinders for the new cylinder giving it the sign and axis of the cylinder not nsed for the sphere. Examples: 1. + 2 cyl. ax. 90 I — 1 cvl. ax. 180 = +*^2.00 sph. I —.)i cvl. ax. 180. 2. or — 1 sph. _ A- 3.00 cyl. ax. 90. ^Measurement of Patient's Glasses : While it is perhaps unwise for a beginner to risk the possibility of biasing his judgment by measuring the glasses the patient has been wearing before completing his own examination, no examination is to be regarded as complete that does not c o n t a i n a record of the ])re- s c ri ]) t i () n he is To deter- mine the strength of a spectacle lens, one may use the general lens meas- ure (Bray ton ])a- tent Figure 197). which gives the curvature of instantlv so tliat the dioptric Measure the two surfaces strength may be found by a simple calculation, or their strength may be determined by neutral i/ation which pro- cess all operators should undei'stand. 214 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Neutralization of Lenses: In neutralizing a lens, the first step is to determine whether it is convex or concave and whether or not it contains a cylinder in which event its axis must be located and the test for plus and minus made in and at right angles to this meridian. To determine whether the lens is convex or concave, if its curvature is not so great as to make its character obvious, look through it at a distant object which will be observed to seem to move as the lens is moved slightly from side to side. If the object moves opposite the direction of lens movement, it is convex; and if in the same direction, it is concave. Should there be no move- ment, it must be a piano. To determine the presence or absence of a cylinder, look through the lens at some object, preferably a line that cannot be seen in its entirety while looking through the lens, meanwhile, slowly rotating it. If the line remains continuous the lens contains no cylinder; but if the line becomes broken diu-ing the rotation, a cylinder is present and its axis lies in one of the two meridians in which the line was not broken. With the character of the lens determined, it is neutralized by placing spheres of the opposite sign in contact with it and repeating the move- ment test, varying strength of neutralization lens until there is noted and recorded that having the strength of the lens under examination, using, of course, the opposite sign. When a cylinder is present the same procedure is followed save that it must be done in both principal meridians FRAME FITTING 215 obtaining a result in crossed cylinders which may be transposed according to the rules just given. FRAJVIE FITTIXG: Extreme irnportance With the best ])ossible form of lenses selected, they must be mounted accurately, safely and attractively before the patient's eyes. The choice between the eye glasses and spectacles, either of which may be rimless or in frames, may usually be left to the patient with certain reservations, save in the case of young children who invariably should be given frame spectacles. Choice of jNIounting: If the ])atient have no astigmatism and so desires he may be given regular eye glasses ; but if he has an astigmatism it is safer for him to wear either a finger piece mounting or spectacles, since the regular eye glasses get out of adjustment readily and the cylinders off axis. Having determined on the form in which the lenses are to be mounted, the next step is to select the size of mounting best suited to the patient's needs. This can best be done by means of fitting sets of standard sizes of bridges which can be procured in either eye glasses, (Figure 198) or spectacles (Figure 199) from any whole- sale optician. 216 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION Fig. 198. Nose Mountings Fig. 19i). Spectacle Fram I N T E R P U P I T.- LARY Distance : We !i c) w deter- iiiiiie t li e inter- ])U])illarv distance by actual meas- urement, usually measuring from the inner -margin of one ])upil to to the outer mar- gin of the other with the patient looking at the dis- tance at w h i c h the glasses are to be used. FRAME FITTING 217 III ])ractice tlic ])atient looks over the o])erator\s head for (hstance aiul at his nose for near. When measuring the inter-])ii])inarv distance one shoidd rememher too, that the eyes are not always equi- distant from the mid line, and, if so. order his mounting of frame accordingly. Selec'J'iox of Lenses: With the individual mounting selected and the inter-pupillary dis- tance known, we select a lens of such size and shape (illustration of which ma}' he found in any optical catalogue) as will place their o])tical cen- ters exactly hefore the pupils and at the same time look well on the patient's face. If there be a great disparity between the inter-pupillary distance and the size of the face and features, or one eye be farther from the mid-line than the other, decentering of one or both lenses may be necessary. ^NIeasukemext fok Spec'Tac'LEs: When order- ing spectacles, in addition to the inter-pupillary distance, one must determine the distance between temples, also the temple length. Frame Fitting in Pkesbyoi'ia: Originally ametropic i)resbyopic patients were given two ])air of glasses: but at present, whenever ])ossible, the distant and near coi-rection are placed in the same mounting in some form of bifocal. Km- metro])ic pi*esl)yo])es also frecjuently object to the blurred distant vision when they look up from near work and aAoid it by adding their presbyopia correction to a ])lan() for distance. Several forms of bifocals have been devised, the efforts for im- 218 OPHTHALMOSCOPY, RETINOSCOPY AND REFRACTION provemeiits being directed to making the junc- tion of the near and distant corection invisible; but the one point that must be remembered is, with the main portion of the correcting lens centered for distance, to have the reading scales decentered inward two millimeters. Adjustments: With the greatest possible care in frame fitting adjustments Avill be found necessary and one will need to provide himself with suitable pliers and learn to use them. A few dollars invested in a supply of the various mountings and spectacles in the cheaper grades and time spent in adjusting them to different faces will well repay one in the satisfaction to his patients that the wearing of a proper correc- tion properly mounted always brings. INDEX Page Aberration, spheric 204 Accommodation 93, 160 Amplitude of 161 Acuity, visual, testing 129 Amblyopia 105 Aphakia 178 Arteries, retinal 15, 19 Astigmatism: Causes 171 Charts 131, 17(i Diagnosis of 171. 177 Forms of 173 Hypermetropic 181, 198, 199 Irregular 202 Mixed 177, 201 Myopic 200 Prevalence 175 Regular 174 Retinoscopy in 197 Symptoms 175 Atrophic spots in retina 16 Atropin 158, 206 Atrophy of oplic nerve 33, 59. 61, 96 Axonometer 1 93 Blood, pressure of 1 05 Blood, vessels of retina 11. 19 Campimeter 80 Case, trial 126 Cataract 101 Charts 127, 131, 176 Choked disc do Choroid : Coloboma 41 Diseases 39 Injuries 49 Rings 15 Rupture 49 Sarcoma 41 Choroiditis : Central 51 , 53 -Disseminated 47 Posterior staphyloma 45 Conjugate foci ; . . . 119 Cyclopegia and Cyclopegics 158, 159, 205 Cylinders, crossed 133 Page Dioptre, value of -i Disc: Blank 125 Choked 65 Pinhole 125 Placedo's 112 Distance, interpupillary 216 Duboisin 206 Embolism of Central Artery of Retina 35 Emmetropia 164., 195 Eserin 113 Esophoria 185 Examination of eye: With opthalmoscope 97 With schematic eye lU, 14 Eupththalmin 206 Eye, direct examination with ophthalmoscope 14, 97 Fundus of human 14, 19, 90, 95, 104 Injury of, by fragment of steel 55 Normal 11, 94 Schematic, examination with 14 Schematic, for ophthalmoscopic study 7 Exophoria 1 85 Field, glaucoma 79 Haeminopsia 81 Hysteria 81 Normal 78 Optic atrophy 79 Retrobulbar neuritis 81 Of vision, taking, with perimeter 77 Of vision, taking, without perimeter 74 Fisher's lid hooks 107 Focus, conjugate 119 Of lens 118 Fogging system 1 34 Frame, trial 1 23 Frames, lens, fitting of 215, 217 Fundus, of human eye 14, 19, 90, 95, 104 Glaucoma 71, 110 Hemorrhagic 73 Vision in 79 Hemianopsia, field in 81 Heterophoria 185, 187 Homatropin, use (^f 158, 206 Hooks, lid, Fisher's 107 Hyoscyamin 206 Hyperesophoria ] 85 H^T>e^exophoria 185 Hypermetropia 27, 166, 195 1'age Hypophoria 185 Hysteria — fielrl of vision in 82 Illiterate, chart for HT Illumination for ophthalmoscopy ... Ol)li(|ue 84 Images, production of 117 Indicrs of refraction A'i'.i Injury, by fragment of steel in eye o") Jaeger's test type 1'5" Kerato.scope 171 Lachrymal .sac 99. 10(1 Lens, action of. laws 1 Hi. H"^ Test H;^ Lenses : Concave 1 1 H Convex 117 ('orrections of various conditions with H-2 Cvlindrical HI. H+ Foci of 118 Forms 209 Material _ A'2i Measurement, prescription writing -209. ^17 Meniscus "209 Mounting 215 Neutralization 214 Selection of 217 Transposition 209 Toric. 209 Lid hooks. Fisher's 107 Light, for opthalmoscopy 84 Nature and j)roperties 110 Refraction of 1 H» Source of 1 3, 84 Lines, white S9. 10* Maddox rod ISC Measurement of len.ses 209. -217 Meridians, principal 191 Mountings, for lenses 215 Mydriatics 205 Muscular insufficiencv 185 Myopia ' 2.S. 1(59, 196 Myopic crescent 2:? Nerve, field 42 Optic atrophy 59. (51. 96 Optic, diseases of 57 Optic, head of 11. 19. 103 Optic, opaque fibers 63 Optic, swollen 65. 67. 69 Page Neuroretinitife 67 Neuritis, retrobulbar 81 Xugent's rule 202 Oblique illumination 84 Ophthalmometer 172 Ophthalmoscope : Electric 3 Loring 3 T'se and description of 1 Ophthalmoscopy, direct 74, 86 Indirect 84 Optic nerve, atrophy 59, 61, 96 Diseases of 57 Head of 11, 19, 103 Optical principles 116 Orthophoria 185 Papillitis hemorrhagica 69 Paracentesis 115 Perimeter 74 Phorometer, trial frame 156 Phoria : Prism treatment of 187 Phoro-Optometer 154, 157 Pigmented spots 16 Placedo's disc 171 Plus tension Ill Position in eye examination 13, 86 Presbyopia 182 Prisn^ 120 Pupil, occluded 114 Distance between 216 Size of 8 Refraction, applied 160 Indices : 123 Rules for correction of 132 Static errors of 122 Refractor, dvnamic 154 Retina ' 11 Atrophic spots in 16 Blood vessels 15, 19 Detachment of 27 Diseases of 25 Embolism of 35 Light streaks, or -white lines 89, 102 Red reflex 102 Vessels 11, 19 Retinitis: Albuminuric 37 Luetic 32 Pigmentosa 31 Retinoscopy 188 Application of 194 Value of 20.5 Reversal, point of 193, 203 Rings, choroid 15 Scleral 15 Rule, Nugent \s 202 Rules, for fogging 135 For hypermetropia 12 For mvopia 12 For refraction 132, 181 For retinoscopy 191 For taking fields 92 Schematic eye 14 Examination of 10, 14 Scleral rings 15 Scopolamin 206 Scotoma, central 76 Screen, with schematic eye 15 Ski-Optometer 155 Snellen's test types 127, 128 Spectacles: Measurement of 213 Spectrum 119 Spheric aberration 204 Spots, atrophic 16 Pigment 16 Squint 1 85 Staphyloma with Choroiditis 45 Stenopic slit 175 Systemation examination of eye 97 Tension 112 Causes of Ill Plus Ill, 112 Prognosis of 112 Treatment of 1 12. 1 14 Test lens : ...]16 Type 127, 130, 184 Tonometer 108-109 Transposition of lenses 209 Trial case 126 Frame 123 Type, Jaeger's test 130 Near test 18-4 Vision : Acuity, testing 129 Taking field of 74, 77 Visual acuity 129 Testing 129 Model "A": a, superior turbinate; b, agger nasi; c, depression above c, superior meatus; d, middle turbinate; e, depression above e. middle meatus; f, inferior turbinate; g, depression above g, in- ferior meatus; h, frontal sinus; i, ethmoidal cell; j, eustachian orifice; k, sphenoidal sinus. Model "B": a, a, anterior ethmoidal cells; b, b, b, posterior ethmoidal cells; c, sphenoidal sinus; d, superior turbinate; e, depression above e, recessus sphenoidalis; f, middle turbinate; g, s])ace above g, middle meatus ; h, inferior turbinate; i, inferior meatus; j, lacrimal duct; k, depression below k, maxillaryostium; 1, bulla ethmoidalis; m, opening po^slerior to m, ostium of bulla ethmoidalis; n, de- pression below n, hiatus semilunaris; o, ring vicious circle; p, depression posterior to p, frontonasal duct; q, frontal sinus; r, eustachian orifice; s, ridge posterior to s, processus uncinatus. Internal Nose Models W. A. Fisher, M.D. Chicago F.A.C.S. It is (litiicult 1o teach nasal siirger}- without a good understanding of the anatomy , and the subject is not an ea.sy one to teach from drawings. The models are sug- £^ested to replace wet spec- imens and may be studied with any text on the sub- ject. The}' are made of rubber, natural in size, [)ractically indestructible, not unsightly and can be used for study in the ph}-- sician's office or for dem- onstration in the operating room. For the general practi- tioner and rhinologist, the models are suggested as an aid in diagnosis and treating focal infections of nasal origin, as well as laying the foundation for nasal surgery. Internal Nose, per pair, $5.00 Postpaid on approval W. A. Fisher, M. D. 31 N. State Street CHICAGO, ILL., U. S. A. Dark Normal Fundus Plate I, Light Normal Fundus Plate II. Myopic Crescent Plate III. Detachment of Retina Plate IV. Retinitis Pigmentosa Plate V. Retinitis Pigmentosa with Oblong Disc. Plate VI. Opaque Nerve Fibn Plate XIX. Plain Choked Disc Plate XX. Neurorentinitis Plate XXI. Pap::,:-:- Plate XXII. Glaucoma Plate XXIII. Plate XXIV. Wi /is her - 111 1 . li Opht ha Imo s c opy , FF39o retinoscopv and 1922 refraction. Biomedical Library A 000 386 660 Biomedical Library m F5390 1922 VV*