DPHTHALM1C METHODS 
 EMPLOYED FOR THE 
 RECOGNITION OF NERVE 
 DISEASE. 
 
 BY 
 ARLES A. OLIVER, A.M., M.D.
 
 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES

 
 PLEASE RETURN TO 
 WM.WOTKYNS SEYMOUR, M n 
 
 TO COMPLETE FILE.
 
 A DESCRIPTION 
 
 OF SOME OF THE 
 
 MOST IMPORTANT OPHTHALMIC METHODS 
 
 EMPLOYED FOR THE 
 
 RECOGNITION OF PERIPHERAL AND 
 CENTRAL NERVE DISEASE. 
 
 BY 
 CHARLES A. OLIVER, A.M., M.D., 
 
 Attending Surgeon to Wills Eye Hospital ; Ophthalmic Surgeon to the Philadelphia Hospital ; 
 Consulting Ophthalmologist to the State Asylum for the Chronic Insane of Pennsylvania. 
 
 PHILADELPHIA: 
 
 UNIVERSITY OF PENNSYLVANIA PRESS. 
 1895.
 
 Copyrighted by 
 
 UNIVERSITY OF PENNSYLVANIA PRESS. 
 1895-
 
 PLEASE RETURN TO 
 
 C 
 
 TO 
 
 S. WEIR MITCHELL, M.D., LL.D., HARVARD, 
 
 WHO WAS THE FIRST TO THOROUGHLY APPRECIATE BOTH THE THEO- 
 RETICAL AND THE PRACTICAL BEARING OP HYE-STRAIN UPON 
 CENTRAL AND PERIPHERAL NERVE-DISORDER, AND TO 
 BRING THIS MOST IMPORTANT BRANCH OF SCI- 
 ENTIFIC MEDICINE INTO EVERY-DAY 
 THERAPEUTICS, THIS LITTLE 
 WORK IS, BY PERMISSION, 
 
 DEDICATED 
 
 AS A TOKEN OF THE RESPECT AND ESTEEM IN 
 WHICH HE IS HELD 
 
 BY THE WRITER.
 
 A DESCRIPTION OF SOME OF THE MOST IMPORTANT 
 
 OPHTHALMIC METHODS EMPLOYED FOR THE 
 
 RECOGNITION OF PERIPHERAL AND 
 
 CENTRAL NERVE DISEASE. 
 
 THE methods for the determination of the ocular signs of general 
 neuroses and related symptomatic local disorders divide themselves into 
 four groupings. The first, by reason of the comparative anatomical 
 simplicity of the structures to be studied and the ease of recognition of 
 related physiological action, constitutes the most important and the 
 most readily understood of all of the ophthalmic methods that are 
 employed in the objective plans for the determination of the physical 
 conditions of the sensory groupings of the visual apparatus. The 
 second, which in reality is a direct sequence of the first, consists in the 
 contrivances and plans that are intended for the recognition of the 
 various subjective sensory symptoms of the apparatus. The third, the 
 least complex and the easiest of comprehension of the entire grouping 
 of procedures, is the series for the determination of the objective motor 
 symptoms. The fourth, though in fact at times constituting the most 
 important of all the clinical methods, consists in the plans that are 
 necessary for evolving the existence, kind, and degree of the subjective 
 
 5
 
 6 Important Ophthalmic Methods Employed for the 
 
 motor groupings. 1 Thus subdivided, the methods for research can be 
 easily understood, and the significance of the findings can be readily 
 realized. Not that any one plan can be relied upon to give proper 
 answer as to the causal lesion : not that any single grouping of simple 
 procedures is sufficient to vouchsafe an adequate diagnosis. Each form 
 of relevant physiologic action and every variety of related anatomical 
 structure must be carefully studied and conscientiously looked at 
 seriatim by the aid of some of the most important and the best adapted 
 clinical methods. This, done not only once, but repeatedly and at 
 regular intervals from the very first suspicion of neural disorder, will, 
 when carefully performed by competent observers, frequently afford 
 much clinical data towards the correct and early diagnosis of grave 
 nerve-disease that ofttimes may thus be checked by appropriate hygienic 
 and therapeutic measures. 
 
 OBJECTIVE DETERMINATION OF SENSORY SYMPTOMS. 
 
 Taking the plan for the objective determination of the sensory 
 groupings first, we are at once placed before the most important, the 
 most comprehensible, and the most pretended of the procedures, 
 ophthalmoscopy. 
 
 1 The topics in this monograph are BO arranged that the reader may at a glance be able to 
 group those methods of precision that pertain to the recognition of allied conditions, thus placing 
 the entire subject-matter in a logical and definitive order, a plan that becomes eminently useful 
 In the careful study of the various neuroses. Of course, every case should be submitted to a routine 
 plan of examination.
 
 Recognition of Peripheral and Central Nerve Disease. 7 
 
 Given a good instrument and a carefully-trained eye, the observer 
 has an ample opportunity set before him in the vascular and the neural 
 circles spread before his gaze to formulate correct opinions not only as 
 to the character of local disease of the intra-ocular media and tunics, 
 but as to the character of many general disorders that are prone to 
 afford intra-ocular expression of their ravages. 
 
 For this purpose there are two methods. One is known as the 
 direct or upright method, where the observer looks directly upon an 
 upright image. The other is termed the indirect or inverted plan, 
 where an aerial image or an indirect picture, which is both inverted 
 and reversed, is seen. In the former, the observer, who should be 
 upon a somewhat higher level than the patient, sits at the side and 
 slightly in front of him. The source of illumination, which should be 
 single and steady, is to be placed at the back and to one side of the 
 patient, so that his eye is in shadow and that an angle of about fifteen 
 to thirty degrees is formed between the patient's eye, the observer's eye, 
 and the light. The observer should next so place his instrument before 
 his own eye with the mirror partly facing both the patient's eye and 
 the light in such a way that he can look directly through the sight- hole 
 of the instrument into the pupil of the patient's eye. If this has been 
 done correctly, the patient's pupil will, if clear, become almost uni- 
 formly red in appearance. The observer thus knows that he has 
 illuminated the interior of the patient's eye, and that he has, in conse- 
 quence, obtained the so-called red fundus-reflex. The increased power
 
 8 Important Ophthalmic Methods Employed for the 
 
 of magnification of the apparent size of the fundal elements over the 
 continental methods of ophthalmoscopic study by this method may, by 
 proper contrivances, 1 as suggested to the writer by Dr. S. Weir Mitchell, 
 be still more greatly enlarged, so as to examine almost microscopically 
 any specially desired detail, thus rendering this method far better than 
 the indirect plan. 
 
 To properly employ the direct method, the observer should first 
 search for changes in the cornea. By employing a sixteen- to thirteen- 
 diopter-strength lens in the instrument and gradually decreasing the 
 focus of the lens to twelve-, ten-, and nine- diopter strengths for the ante- 
 rior capsule, the cortex, nucleus, and the posterior capsule of the lens, 
 most of the structures in the anterior segment of the eye can be succes- 
 sively studied. The lens-strength should then be weakened as the 
 vitreous chamber is more and more deeply penetrated. As soon as the 
 fundus is reached, the optic-nerve-head is the first portion to be sought 
 for. This can be easily accomplished by following the course of one 
 of the main retinal stems up to that portion of the eye-ground that 
 appears like a pinkish-white gray plaque or disk. Found, its apparent 
 size, measured in a number of diameters of one and a half millimetres 
 each (which represents its real size), should next be noted. Its axis of 
 greatest length as gauged from a horizontal zero, the comparative tints 
 of its different quadrants, its irregularity of surface contour, the dis- 
 
 1 The writer, at the suggestion of Dr. Mitchell several years ago, is at the present time per 
 fecting such an instrument.
 
 Recognition of Peripheral and Central Nerve Disease. 9 
 
 tinctness of its borders, and the degree of pigment absorption beyond 
 its edges, should all be accurately recorded. In fact, any normal or 
 abnormal condition, both neural and vascular, that may seem worthy 
 of notice, should be carefully registered upon suitable blanks. The 
 comparative sizes of the retinal vessels, the relative tint of the contained 
 blood, the thickness of the channel- walls, their tortuosity and wavi- 
 ness, the widths of the light-streaks, and the visibility of the lymph- 
 sheaths next demand attention. The appearance of the macular region 
 with its contained yellow spot, the general tint of the fundus, the 
 amount of absorption of pigment epithelium, the degrees of choroidal 
 disturbance, the character of the general pacification of the retina, 
 especially any increase in the thickness and the visibility of its fibre- 
 layer, and the kind and amount of ametropia should be registered in 
 every case. If to these the ordinary variations in fundus-structure, 
 which serve as the basis upon which to build, as it were, any patho- 
 logical conditions be added all gross changes as tersely and as clearly 
 expressed as possible, this form of ophthalmoscopic record becomes, in 
 due proportion to its degree of completeness and correctness, a valuable 
 guide to both the general and the special student in neurology. 
 
 Should desire be had for a large field of vision in which accurate 
 details are not necessary, as, for instance, to obtain a general view of 
 the appearance of the fundus, just as is so frequently done by weak 
 objectives in topographical microscopy, the other method may be 
 employed, where, instead of directly approaching the patient's eye
 
 io Important Ophthalmic Methods Employed for the 
 
 with the ophthalmoscope and looking directly upon the fundus, the 
 instrument is held at some forty-five to fifty centimetres away from the 
 eye to be studied. By this plan, the details of the fundus are projected 
 into the air as an inverted and reversed image. As so much of the eye- 
 ground is given at a single glance by this plan, thus offering a better 
 idea as to the exact location of pathological changes, it should always 
 be employed by the special investigator. 
 
 To obtain the best results by the inverted method, there should be, 
 as in the first plan, a single source of illumination. If desired, an 
 incandescent loop of electricity of about sixteen to twenty candle- 
 power, which, whilst not being too intense in illumination, closely 
 simulates ordinary solar light, can, just as in the other method, be 
 used. 1 The source of light should be so placed at the back and to one 
 side of the patient that his eye is in shadow. An ordinary concave 
 mirror ophthalmoscope is then to be held directly in front of the 
 observer's eye, so that he can look through the sight-hole of the 
 instrument. The observer should be seated at about fifty centimetres' 
 distance in front of the eye to be examined. If a strong biconvex lens 
 is held in the observer's other hand between the eye to be examined 
 and the instrument, a small inverted and reversed aerial image of the 
 details of a large area of the patient's fundus or any other portion of 
 
 1 The writer prefers this illumination to the yellowish-red light by the burning of impure 
 carbohydrogen compounds. Of course, however, this is a mere personal preference that the 
 reader is not asked to coincide with.
 
 Recognition of Peripheral and Central Nerve Disease. 1 1 
 
 the interior of the organ situated in the so-called ophthalmoscopic field, 
 will be seen. By constantly changing the relative positions of the mirror 
 and the lens with the light and the patient's eye, both the lateral extents 
 and the antero-posterior portions of the ophthalmoscopic area can be 
 successively searched for pathological change. If an enlarged field of 
 illumination, though, of course, not so brilliantly an illuminated one, 
 be desired, a plain mirror can be substituted for the concave one. 
 
 If the observer is able to sketch or to paint, much aid may be 
 offered to him in the future conception of the ophthalmoscopic pictures 
 by making either careful drawings upon prepared sheets, as in Haab's 
 plates, which are composed of superimposed layers of chrome-yellow 
 and cinnabar over sheets of a dull white ground, or pen-and-pencil 
 sketches that are designative of the most important changes seen. To 
 assist him in this, Tiffany's sketching blanks, which are ruled in pro- 
 portionate size to the apparent magnification in the upright image, may 
 often be useful. Bellarminoffs method a mere modified revival of the 
 old plans of orthoscopic study of examining the fundus of the eye by 
 pressing a piece of plain glass against a cocainized cornea so as to 
 flatten that membrane and thus allow the details of the eye- ground to 
 become visible, might under certain circumstances be of value where 
 no better instrument of precision is at hand. Here, however, the 
 details are quite minute in size, a difficulty, nevertheless, that might 
 be lessened by the employment of a magnifying lens in front of the 
 sheet of glass.
 
 12 Important Ophthalmic Methods Employed for the 
 
 One of the most important methods for the objective detection of 
 changes in the sensory portions of the visual apparatus, is that known 
 as oblique, lateral, or focal illumination. In connection with ophthal- 
 moscopy, it lays bare, with the exception of a small ciliary zone, almost 
 the entire internal tunics and refracting media of the eye. With it, the 
 appearance of the entire anterior external segment of the eye, the 
 cornea, the aqueous, the iris, almost all of the lens, and much of the 
 forward part of the vitreous can be brilliantly illuminated and magni- 
 fied. Irritation signs of neural and vascular types, such as epithelial 
 thickenings, swellings, and venous and arterial engorgements, atrophic 
 areas, as shown by denudations of epithelium and blanching and dis- 
 coloration of tissue ; and evidences of old inflammation, as recognized 
 by vascular engorgements ; deposits of false material and thickenings 
 and thinnings of normal structure ; all can be made evident and are 
 readily differentiated by this method. 
 
 One of two plans may be pursued. The first, which is the less 
 preferred, is that by concentrating diffuse daylight upon the affected 
 portion of the organ. The second is that which is accomplished by 
 bringing some of the rays from an artificial illuminant to a focus upon 
 the area that is desired to be the more plainly seen. To do either of 
 these successfully, a strong planoconvex or biconvex lens is held at 
 or about its focal distance from the eye in such a position that the 
 impinging light rays may be concentrated upon the part that is desired 
 to be studied. A second lens of about the same strength or much
 
 Recognition of Peripheral and Central Nerve Disease. 13 
 
 stronger, as, for instance, the so-called "corneal loupe," can then be 
 held at right angles to the illuminating lens in such a position that the 
 observer can look through it at the underlying ocular tissues. If 
 properly done, a highly-magnified and brilliantly-illuminated image of 
 the part looked at will be obtained. 
 
 An excellent plan to determine the existence and the exact position 
 of any area of denudation of the deeper-lying conjunctival and corneal 
 tissues can be taken advantage of by the employment of a drop or two 
 of a 2-per-cent. solution of a sodium or potassium salt of fluorescin. 
 When employed, care should be taken to wash the excess away by some 
 distilled water. If this be done properly, it will be seen that the drug 
 has the power to stain any denuded surface of corneal tissue a deep 
 greenish yellow, whilst it causes breaks in the bulbar and tarsal con- 
 junctivse to become yellow in appearance. 
 
 Where gross lesions about the orbit, as, for instance, when neo- 
 plastic formations in the maxillary antra are suspected, advantage 
 might be taken of the recent proposition of transillumination by 
 electric light. A guarded loop of about five to ten candle-power can 
 be carried far back and up into the nasal fossa. When in this position, 
 the loop can be rendered incandescent. If the procedure be properly 
 done, a coarse configuration of the bony cavities can be well made out 
 and the globes may become partly translucent. In this experiment, the 
 pupil frequently remains dilated and emits a red glare known as 
 Davidson's sign. If there be any degree of lessening of luminous 
 perception, Gavel's sign is said to be present.
 
 14 Important Ophthalmic Methods Employed for the 
 
 In some cases, it may be of value to make a spectroscopic exami- 
 nation of the interior of the eye. This, it is said, can be done by inter- 
 posing a spectroscope in the path of the return rays from an ordinary 
 ophthalmoscope into the observer's eye. By some, it is believed to be 
 of use in the differentiation of hemorrhagic from other forms of intra- 
 ocular extravasation. 
 
 SUBJECTIVE DETERMINATION OF SENSORY SYMPTOMS. 
 
 Passing to the recognition of the next most important series of 
 symptoms, the subjective sensory, the observer will at once encounter 
 what at first sight seems the easiest and the least troublesome to obtain. 
 Owing to these facts, the various procedures are so loosely sought for, 
 and the different results are so imperfectly expressed, that a brief though 
 complete detail of the most important of the methods is necessary. 
 First in the list, is the determination of central vision for form. 
 
 To accomplish this properly, test-letters are to be employed. The 
 best are based upon the fact that as the smallest angle of distinct vi- 
 sion for a normal eye is equivalent to one minute in width, the exact 
 circular area produced by any pencil of light at increasing distances 
 increases in just such proportion, in other words, the greater the dis- 
 tance, the greater the area of the one-minute angle must be. In con- 
 sequence, therefore, every object to be seen distinctly under the angle 
 of minimum visibility, as it is called, must embrace the one- minute 
 area at its equivalent distance. Thus, a letter whose strokes repre-
 
 Recognition of Peripheral and Central Nerve Disease. 15 
 
 sent a width of one minute at one metre's distance from the eye, 
 must be double the size to be properly seen at two metres' distance, 
 etc. 
 
 These letters, known as optotypi or test-types, are so arranged 
 in sequential order of size, that fractional values of the degree of 
 visual acuity can be readily obtained. To do this correctly, the card 
 is to be suspended upon a well-lighted wall in such a way that the 
 patient has his back to the source of light, and his eyes on a level 
 with the smallest type that is intended to be seen at the chosen dis- 
 tance. One eye should be tried at a time. Care should be taken 
 that the fellow eye is secured from participation in vision by a band- 
 age or a shade. Preferably, the vision of the supposed weaker 
 organ is to be tried first. All the examinations should be made 
 both with the vision uncorrected, and when it is corrected by appro- 
 priate lenses. 
 
 If, as is preferred by some, artificial illumination be desired, the 
 source of light should be shaded from the patient by an appropriate 
 shade. Should the test-types be ruled to decimal divisions, as they 
 are in the writer's series, the patient is to be placed at five metres' 
 distance from the card. Should he be able to correctly call the letters 
 in the five-diopter line of type at the five metres' distance, his vision 
 is said to be normal. The way this is expressed is in the form of a 
 fraction, using the number of metres employed as the numerator, and 
 
 the size of the type seen as the denominator : thus, - or - , signifying
 
 1 6 Important Ophthalmic Methods Employed for the 
 
 - vision. If the smallest line of type seen at five metres' distance is 
 
 i 
 
 the ten-diopter line (that is, what a normal eye can recognize at ten 
 
 metres' distance), the fraction would read , denoting - vision. If the 
 
 10 e 2 
 
 forty-diopter line be the smallest type that can be seen at five metres' 
 distance, the fractional value would be one-eighth, as specified by 
 
 . Should it be necessary to bring the patient nearer to the card to 
 
 see the forty-diopter line of type, the actual distance necessary to bring 
 him to, should be used as a numerator with the 40 as the denominator. 
 Thus, if the new distance be two metres away from the card, the frac- 
 
 2 
 
 tional value would read , stating that the patient had but one-twen- 
 
 4 
 tieth of normal vision. If vision be still more defective than can be 
 
 obtained by the cards, the patient should be made to count the number 
 of fingers that the observer raises and constantly varies ; the first essay 
 being made at five metres' distance with the patient's back to the source 
 of light. If vision be still lower, the patient should be made to gaze 
 at a single source of definitely-graded illumination in a darkened room. 
 The farthest distance that the light can be recognized is to be noted as 
 
 "Light perception at metres." If vision be still more defective, 
 
 the patient is to be brought directly up to the source of illumination 
 and wheeled around so that he faces it. A strong convex lens is then 
 to be held directly in front of the eye, and varying strengths of con- 
 centrated light are to be brought to play upon the organ at different
 
 Recognition of Peripheral and Central Nerve Disease. 17 
 
 angles and meridians. If the patient fails to recognize any difference, 
 and if he cannot tell when the eye is shaded and when it is exposed, 
 it is probable that he cannot see at all, and the result should be noted 
 with the word "Blind." 
 
 In all of this work it must be definitely understood that, dependent 
 upon the patient's occupation and trained mode of employment of his 
 eyes, there is a marked difference of practical value between the real 
 visual equivalent and the necessary functional one. 
 
 In many instances, it is of value to study what is known as 
 direct vision for color. To effect this easily and properly, sheets of 
 gauged color squares, similar in size to those of the test-types, or 
 contrivances intended to expose definite areas of colors, are to be 
 employed. 
 
 The average area to be exposed for the recognition of a few of the 
 most important colors used at five metres' distance is 2f millimetres 
 exposure for red ; 8 r 3 F millimetres for blue ; loft- millimetres for green ; 
 and 22 T 9 e- millimetres for violet. Cards with these quotients arranged 
 at five- diopter differences in size can be made and used in the same 
 way for ordinary routine use as test-types. In all of these tests, 
 just as in those for the determination of central vision for form, note 
 should be made whether any manifest refractive error has been cor- 
 rected or not. 
 
 In all cases, especially where there is any suspicion of subnormal 
 color-perception, more careful testing becomes necessary. The easiest
 
 1 8 Important Ophthalmic Methods Employed for the 
 
 and most comprehensible method is that with the color yarns of Holm- 
 gren. Three large skeins, light green, purple, and red, known as 
 ' ' test-skeins, ' ' are to be separated from a bundle of smaller pure and 
 confusion skeins, which have been promiscuously thrown upon a large 
 flat table. The patient is first requested to match the green, then the 
 purple, and lastly the red skein as near as possible, without naming 
 the colors. If any abnormality in the color-sense be present, it will 
 soon evidence itself by the choices that the patient makes. Holmgren 
 says that if the first two tests show a decrease of the color-sense, the 
 last can be omitted. 
 
 An easier and more accurate method, and one that is less expen- 
 sive as to material and to time, is that almost daily pursued by the 
 writer. In this test, there are but twenty-three skeins, eighteen of 
 which are match-skeins, and the remaining five are test-skeins. The 
 five test-skeins are pure green, pure red, rose, pure blue, and pure yel- 
 low. One or two choices among the match-skeins are to be made for 
 each of the principal tests. Where absolute accuracy as to the degree 
 of the color-sense is not necessary, the first three tests only need be 
 employed. Each skein is designated by a mark that can be understood 
 by the educated examiner, and also, just as with the test-type, is made 
 intelligible to the whole ophthalmic world. Each skein is so dyed that 
 its color-equivalent is absolutely fixed, and all of the match-skeins are 
 of the same relative intensity, thus preventing the patient from judg- 
 ing a tint by differences of shading, a power that such subjects possess 
 to a remarkable degree.
 
 Recognition of Peripheral and Central Nerve Disease. 19 
 
 In many cases of hemicrania, where the patients are intelligent 
 (and, fortunately for the observer, this is the class of subjects in whom 
 this series of phenomena is most often found), much information can 
 be gotten as to the character and the position of the disorder by close 
 questioning as to the direction of movement of paresthetic and anes- 
 thetic areas, both in their onsets and disappearances. Study of the 
 coloration and the configuration of the phosphenes, the order of the 
 visible expressions of the attacks, etc., are all of value. 
 
 In contradistinction to the plans for the determination of direct 
 vision for form and color, those for the proper recognition of peripheral 
 or indirect vision should also be studied. The art of obtaining such 
 answers is known as perimetry. The procedure can be effected in three 
 different ways, all having the one principle of a fixed point upon 
 which the patient must gaze whilst a peripheral object is being brought 
 into view. The easiest, and the way that the observer will most fre- 
 quently be brought into contact with in the bedroom, is, where there 
 is not any special form of apparatus. Here the patient can be made to 
 gaze steadily at one of the observer's uplifted fingers, held at about 
 thirty centimetres from his eye. This done, the observer moves a small 
 color-slip or his own upraised finger-tip inward in various directions 
 towards the fixation-object. This plan is of frequent use where rough 
 and ready tests for the mere determination of gross changes in the field 
 of vision are desired. 
 
 The next most useful method is that with a ruled black-board which
 
 2O Important Ophthalmic Methods Employed for the 
 
 has been gauged into some definite form, as, for instance, into concen- 
 tric circles of five-degree differences of separation, or squares of seven 
 and a half centimetres each. 
 
 In the centre of the board there is a cross which serves as a fixa- 
 tion-point. Definitely-sized areas of squares or circles of various col- 
 ors, fastened on long black rods, are then to be gradually moved from 
 the periphery of the board in towards the central point until the color 
 is properly named. The moment that this is done, a chalk-mark 
 preferably the initial letter of the color employed is to be made on the 
 board at the point where the color has been correctly designated. All 
 the marks for the same color are to be connected to one another by 
 lines. Transcripts upon proportionately ruled miniature board-blanks 
 can then be made for future reference. One eye is to be tried at a time, 
 always choosing the more defective one first. The other is to be care- 
 fully excluded by a turn or two of a roller bandage or a handkerchief. 
 The board should be placed in a good light and at such an angle that 
 the patient's head and body do not cast any shadow upon it. The 
 physiological blind spot should always be searched for, and its posi- 
 tion and size are to be accurately noted. Areas of dimmed and blind 
 spots, or scotomata, as they are called, are to be carefully sought for, 
 especially for the colors red and green. This can be done by moving 
 the little color squares or circles over the entire field area. If blind 
 spots are determined, they should be noted in their respective positions 
 upon the blanks.
 
 Recognition of Peripheral and Central Nerve Disease. 21 
 
 The third plan, which is extremely valuable when careful scientific 
 study with the fewest loop-holes for error is necessary, is that where 
 some form of the so-called perimeter is employed. The plan is prac- 
 tically the same as in the other two methods, differing merely in the 
 technique that is necessary for the peculiar mechanism at hand. Some 
 of the best forms of perimeters have self-registering apparatuses into 
 which the little register-blanks can be slipped. 
 
 In all of this work, the color areas should be frequently changed, 
 tried at various distances from the eye, under varying grades of external 
 stimuli, and substituted for one another in numerous ways. 
 
 Should vision be so low that it becomes merely quantitative, and 
 no definite form can be recognized, the field of light-projection, as it is 
 termed, should be mapped out. This can be accomplished in the same 
 manner as with form and color, except that here the fixation-object is 
 made by having a point of strong light-stimulus, such as a candle- 
 flame. The movable object to register the periphery and the scoto- 
 matous areas of the field, should be some form of equally strong light- 
 stimulus. The registries are to be made in the same manner as in the 
 other methods, except that here the notes are designative of ' ' candle 
 field' ' or ' ' quantitative field for light. ' ' If possible, graduated beams of 
 light should be used. Another good plan to accomplish the same pur- 
 pose is to place the patient in the ordinary ophthalmoscopic position, 
 and have him gaze directly ahead. The unused eye should be carefully 
 covered. A beam of light from a concave, or if weaker stimuli be de-
 
 22 Important Ophthalmic Methods Employed for the 
 
 sired, a plane mirror, should be flashed upon the exposed eye from 
 various peripheral points whilst the patient is made to gaze directly 
 ahead. The varying positions of the light are then to be named with- 
 out allowing the patient to move the eye away from the fixing point. 
 A rough field of light-projection, which is often of incalculable value 
 in many cases of marked nerve-disease, is thus otained. 
 
 In addition to the above methods for the subjective determination 
 of the conditions of the sensory portions of the visual apparatus, there 
 are several other plans which are of importance in the recognition of 
 central and peripheral nerve-disease. These, which are frequently 
 omitted from routine ocular examination, are combined in the study of 
 the sensibility of the superficial portions of the organ and its adnexa. 
 For this purpose, esthesiometers of various kinds, with specially adapted 
 points for the cornea, can be used to determine sensibility. Wisps of 
 cotton, carefully twisted and coiled upon the corneal surface without 
 touching the lid-edges, may be employed to study the sensibility of 
 this membrane. I^ocal thermometry on and around the anterior face 
 of the eye, can frequently be used to great advantage in the ready recog- 
 nition of atrophic and degenerate areas from peripheral nerve-disease. 
 Again, if local inflammation be present, pressure with the finger-tips 
 upon or over the affected parts, may often evoke its presence by evi- 
 dences of tenderness and pain.
 
 Recognition of Peripheral and Central Nerve Disease. 23 
 
 OBJECTIVE STUDY OP MOTOR CONDITIONS. 
 
 Leaving the methods for the recognition of the sensory disturb- 
 ances, the observer is brought to what at first sight seems one of the 
 easiest portions of the examination, that is, the objective study of the 
 motor conditions of the visual apparatus. The muscular movements, 
 however, are so varied in monocular and binocular fixation, and the 
 association of nerve action is so complex in the different physiological 
 acts of the two organs, that the examiner must be mentally well 
 equipped to fully understand the significance of what to the uninitiated 
 may appear to be an indeterminate commingling of movement and 
 action. 
 
 Most important are the procedures for the determination of iris 
 movement. The comparative sizes and shapes of the pupils should 
 first be gauged, the former being accomplished by one of the many 
 forms of pupillometer, and the latter by the use of a twelve- to sixteen- 
 diopter convex lens in the sight-hole of an ophthalmoscope. Should 
 the pupil be round, as it seldom is, the horizontal width should be 
 carefully estimated in millimetre lengths. If the pupil be oval, the 
 lengths of the long and short axes should be determined, and the 
 degree of direction of the long axis should be noted. These deter- 
 minations are to be made during both monocular and binocular expo- 
 sure, whilst the eyes are gazing directly ahead at a distance, and whilst 
 they are fixed upon some near object, situated at about thirty-five
 
 24 Important Ophthalmic Methods Employed or the 
 
 centimetres' distance from the patient's face. This should be done 
 both immediately in front of the singly-exposed organ and on the 
 median line when both eyes are simultaneously exposed. The patient 
 should be made to face a window or some other source of diffuse day- 
 light. If artificial light be employed, a ground glass shade over the 
 source of illumination will be conducive to better results. 
 
 The significance of the size of the pupil itself, although fre- 
 quently unlike in the two eyes of the same subject, may often be 
 taken advantage of for diagnostic purposes. For example, in myopia 
 it is, by reason of relaxation of accommodation and consequent want 
 of impulse of the sphincter muscle of the iris, as a rule, larger than 
 ordinary. It is also large in most of the various forms of so-called 
 amblyopia and amaurosis. In sympathetic irritation, as may be found 
 in the earlier stages of aneurismal pressure on the nerve, it is large. 
 In paralysis of the third nerve, in glaucoma, cerebral compression, neu- 
 roses of functional type, peripheral irritations, it generally becomes 
 dilated. I^ocal application and internal administration of certain 
 drugs, ordinarily known as mydriatics, cause it ; moreover, it must be 
 remembered that it is larger in childhood and in youth than it is in 
 adult life and in old age. On the contrary, it is small in hyperme- 
 tropia. Especially is this so in cases where the patient is continuously 
 using the eyes for close work. In retinal hyperesthesia, in meningeal 
 inflammation, in cerebral irritation, and in certain stages of convulsive 
 seizures, it becomes contracted. It lessens in size during the local and
 
 Recognition of Peripheral and Central Nerve Disease. 25 
 
 general action of certain drugs popularly known as myotics. Decrease 
 of the area is an almost certain accompaniment of increasing age. 
 Frequently, as is so often seen in the early stages of posterior spinal 
 sclerosis and general paralysis of the insane, it will be found to assume 
 all manner of bizarre shapes and irregularities of size. 
 
 All of these conditions should be noted most carefully. 
 
 For the better differentiation of pathological or artificial pupillary 
 disturbances, some one of the numerous mydriatic and myotic agents, 
 such as cocaine, atropine, eserine, etc., can, at times, be employed to 
 advantage. 
 
 Having thus roughly determined the equilibrium of the iris series 
 of muscles, the actions of the sphincter muscles of these membranes 
 ate next to be studied. As these movements are associated ones, the 
 procedures for their determination must be made under definite condi- 
 tions. The first and the most important impulse or reflex act is that 
 known as iris-response to light stimulus thrown upon the retina. To 
 study it properly, the patient is made to face some source of diffuse day- 
 light or artificial illumination. He is then to be directed to keep both 
 eyes open and to gaze directly ahead into space. The two organs are 
 then to be covered and alternately exposed to the entering light stimu- 
 lus until surety is made that there is muscular response or not. If 
 there be any response, it will evidence itself by a more or less complete 
 contraction of a portion or of the entire pupillary area upon exposure 
 of the organ to the source of light. Frequently, in neuroses of degen-
 
 26 Important Ophthalmic Methods Employed for the 
 
 erative type, a series of slowly-decreasing secondary clonicisms may be 
 noticed. These can be best studied by a magnifying lens which has 
 been preferably placed behind the sight-hole of an ophthalmoscope. 
 
 The next so-called pupillary reflex act, or better, iris reflex act, to 
 study, is that existing between the ciliary and the iris muscles. Either of 
 these muscles, as can be determined experimentally, contracts its fibres 
 when its fellow is brought into play. When the reflex movement of the iris, 
 producing pupillary contraction, is brought into action by the contrac- 
 tion of the ciliary muscle so as to allow the lens to increase its power 
 of focussing for near vision, the impulse is known as pupillary response 
 to accommodation. To determine whether this reflex motion is in 
 proper working order, one eye is to be covered from use and the other 
 is first made to gaze directly ahead at a distance. When the pupil of 
 the gazing eye has become comparatively fixed in size, an object, such 
 as the finger-tip or a pencil-point, is to be quickly placed at about thirty- 
 five centimetres in front of the exposed eye, and the patient is requested 
 to look directly at the object. If the reflex be in proper working 
 order, the pupil will immediately contract, to dilate when the fixation- 
 object is removed and the eye is made to regaze into space. 
 
 A third pupillary response (better, iris response) is where the two 
 eyes are made to accommodate synchronously upon a near object, 
 situated upon the median line. Here, in addition to the relationship 
 of impulse between the ciliary and the iris muscles, there is another 
 factor, known as simultaneous contraction of the internal recti mus-
 
 Recognition of Peripheral and Central Nerve Disease. 27 
 
 cles, added. This compound reflex act, which is ordinarily, though 
 improperly, known as the pupillary reaction to convergence, 1 is ob- 
 tained in exactly the same way as it was during the previous method, 
 except that here the fixation object is situated upon the median line 
 and both eyes are coetaneously exposed. 
 
 A fourth response is that in which the pupil dilates when the skin 
 of the back of the neck is pinched. By some it is known as Parrot's 
 sign, and is said to be present in some cases of meningeal inflammation. 
 
 All of these examinations should be repeated frequently, often, 
 taking care in many cases to totally withdraw any form of stimulus 
 from the eyes by temporary bandaging of both eyes, until certainty of 
 result can be vouchsafed. This cannot be too strongly insisted upon, 
 as nowhere in all of the methods of ocular precision, when the reflexes 
 are carefully or properly studied, can so much information be gained 
 as to deep-seated nerve and vascular disorder of motor type as in these 
 most delicate and evanescent tests. 
 
 One of the most important methods of diagnosis is that known as 
 the hemianopic iris inaction sign, or what is popularly known as the 
 Wernicke sign. Here, by the study of the peculiarities of movement 
 of the iris in certain types of hemianopsia, much localizing data can be 
 had as to the position of intracranial mischief. As is well known, the 
 reflex arc for iris movement, when light stimulus is thrown upon the 
 
 1 It would be more fitting to say iris reaction to convergence, as the pupil, being a void, cannot 
 have a reaction.
 
 28 Important Ophthalmic Methods Employed for the 
 
 retina, extends back along the in-going optic nerve-fibres, until when 
 about in mid-brain it associates with the out-going motor nerves of the 
 iris. This, as has been proven anatomically, takes place before the 
 position of the corpora quadrigemina has been reached. This being 
 so, it is certain that, should some break occur within this reflex sen- 
 sory-motor loop back of the optic nerves themselves, that is, in the 
 optic chiasm or in the optic tracts, the want of proper physiological 
 act to any appropriate external stimulus would immediately manifest 
 itself by a failure of response of iris movement, should light stimulus 
 be thrown through the pupil upon the retina. Knowing these facts, so 
 here in hemianopsia, or, in fact, any related field defect, should the 
 lesion be situated in the chiasm or optic tracts anterior to the corpora 
 quadrigemina, the iris muscle will fail to respond when light stimulus is 
 carefully thrown upon the non-receiving portions of the retina. 
 
 To produce the symptom satisfactorily, many plans have been 
 urged. In the writer's experience, the easiest and most practical 
 method consists in simply having the patient placed in the ordinary 
 ophthalmoscopic position, except that the source of light is so situated 
 that the rays will come from over his head. One eye should be tried 
 at a time, it being made to gaze straight ahead into a darkened space. 
 The fellow eye is to be excluded from the entrance of all rays of light 
 into it. The observer, standing in front of the patient, is to faintly 
 illuminate the iris that he wishes to study by means of a piece of plain 
 looking-glass such as is employed in the fundus-reflex test This can
 
 Recognition of Peripheral and Central Nerve Disease. 29 
 
 be done by some permanent arrangement of mirror or by holding a 
 glass in the hand. An ordinary concave ophthalmoscopic mirror is to 
 be held in the other hand and a narrow beam of concentrated light is 
 to be thrown upon the pupil from the periphery of the blind area of 
 the field of vision. This beam is then slowly moved in towards the 
 position of the line of fixation. If the sign be present, there will not 
 be any iris movement until the edge of the retained field area has been 
 reached. At this point, an immediate pupillary contraction will take 
 place. This contraction will persist as long as the light stimulus is 
 kept within the persistent field area. Should the lesion be situated 
 posterior to the corpora quadrigemina, pupillary contraction will ensue, 
 even though the stimulus be presented from the blind portion of the 
 visual field, thus showing that the motor-sensory arc is untouched and 
 unharmed. 
 
 Another sign, known as the Knies pupil-symptom, is well worth 
 searching for. It consists in a hemianopic inaction without a hemi- 
 anopic field-defect, and shows that there is some localized disturbance 
 in the different pupillary reflex path between the third-nerve nucleus 
 of one side and its related tract. In some cases of grave nerve-disease, 
 especially where there is coexistent pupillary dilatation, and no an- 
 swers can be obtained from the patient, much valuable data as to the 
 condition of the ciliary muscle can be objectively obtained by the 
 so-called catoptric test. As is well known, if a small beam of extraneous 
 light be allowed to fall very obliquely upon the pupillary area, and this
 
 3O Important Ophthalmic Methods Employed for the 
 
 area be properly magnified and looked at, three images of the beam will 
 be plainly seen. These images, in their order of succession, are formed 
 upon the anterior convex surface of the cornea, the anterior convex 
 surface of the lens, and the inner concave surface of the posterior 
 portion of the lens. The first two images are large and upright, whilst 
 the third image is small and inverted. In the act of accommodation, 
 which necessarily means a contraction of the ciliary muscle, the con- 
 vexity of the lens increases. This increase in the strength of the lens 
 shows itself by a separation and a change in comparative size of the 
 lenticular reflexes. The lenticular reflex, which is the second reflex 
 seen in the test, becomes larger and slightly moves anteriorly. The 
 posterior lenticular reflex, which is the third reflex of the test, becomes 
 smaller and markedly recedes posteriorly. 
 
 At times, when the pupil is small and when it is impossible to 
 properly study the catoptric images, the plain mirror can be employed 
 to advantage to determine the degree and the amount of accommodative 
 action of the ciliary muscle. If, whilst the instrument is being used 
 to study the play of the movements of the lights and shadows in the 
 fuudus-reflex test, it be gradually approached to the patient's eye, there 
 will be a point that is dependent upon the degree of accommodative 
 power possessed by the organ, at which the movements of the reflexes 
 will be reversed. This point, measured from the anterior surface of 
 the eye, will determine both that there is ciliary muscle action and its 
 degree of power.
 
 Recognition of Peripheral and Central Nerve Disease. 31 
 
 The objective study of the equilibrium, and the determination of 
 the visible motions of the extrinsic muscles of the two eyes, next de- 
 mand attention. In many instances, principally in the incipient and 
 in the irritative stages of nerve- disease, the recognition of minor de- 
 grees of disturbances of these muscles is extremely difficult. Hidden 
 from view, associated in the most complex way in their normal actions, 
 and so readily compensated for among themselves in their faults, their 
 peculiarities of balance and the disturbances of their action are much' 
 less readily recognized upon mere inspection than the peculiarities of 
 their related interior groupings. 
 
 Often, however, a quick observer may notice abnormalities of facial 
 expression, and take advantage of peculiar movements of the head and 
 trunk muscles when certain ocular motions are attempted. Should the 
 patient complain of double vision, one eye will often be found unable 
 to fix upon some object held at about occupation distance (such as 
 reading or sewing) upon the median line. The clinical demonstration 
 of this sign, which can be very readily determined by alternately ex- 
 cluding one of the eyes whilst its fellow is made to gaze at an object, 
 such as a pen-point, held directly ahead of the patient at about thirty- 
 five centimetres' distance, is ordinarily known as the method by exclu- 
 sion. If desired, the degree of deviation of the faulty eye can be esti- 
 mated by the aid of a strabismometer, held in front of each eye. This 
 experiment can be repeated in any meridian of the field of vision that 
 may be desired. In fact, if due allowance for situation be taken, it
 
 32 Important Ophthalmic Methods Employed for the 
 
 may be tried in any position of muscle equilibrium that may seem to 
 be desirable. Again, the degree of rotation effected by the globe and 
 the character of the movement when the eye is made to follow the up- 
 raised finger, is of the greatest importance as an objective test. If 
 there be an irritated or hypertrophied muscle, the movement of the eye- 
 ball in the direction of the muscle will be greater than the movement 
 of the opposite eyeball in the direction of the corresponding muscle. 
 Should there be a paresis of the affected muscle, the movement of the 
 globe to which it is attached will be limited in the direction of the pull 
 of the muscle. An excellent routine in the determination of these 
 conditions is to first consider the monocular movements in the hori- 
 zontal meridian. This is to be followed by a study of the movements 
 in the vertical meridian and at oblique angles. These observations 
 should be repeated with the two eyes simultaneously, taking care in all 
 instances to add the associated physiologic movements, as, for instance, 
 the two interni in maximum convergence and the related external and 
 internal groupings in conjugate deviation. If these tests be properly 
 and intelligently conducted, they will often, especially if the observer 
 be quick and certain in his finger movements, brin^j to light many 
 minor discrepancies of both peripheral and central type that otherwise 
 might escape attention. 
 
 Watch should be made for slight ataxic movements during extreme 
 action of the suspected muscle. Here the eyeball seems to succes- 
 sively recede several times back along its excursional route and regain
 
 Recognition of Peripheral and Central Nerve Disease. 33 
 
 for a second or two its point of limitation of movement, before being 
 able to accurately and steadfastly fix upon the observer's upraised 
 finger. 
 
 In all of this work, it should be remembered that the degree of 
 movement in different directions of any two or more groups of muscles 
 is greatly at variance, not only in respect to the individual strength of 
 the muscles, but also as to the physiological acts that are being re- 
 quired of the muscle-grouping at the time of action. For instance, the 
 lateral movements of the globes, both separately and combinedly, are 
 far greater than the vertical, whilst the utmost degree of the movement 
 of the two interni during the effort for binocular convergence is far 
 less, especially in hypermetropes and in old subjects, than it is when 
 these muscles are separately employed in association with the externi 
 during conjugate deviation. Again, the observer should remember that 
 errors of refraction may so mask the apparent results of the most care- 
 fully performed work that, at times, the most bizarre and seemingly 
 incongruous findings may be obtained. For this reason, therefore, no 
 tests for muscle-balance and motion, unless so marked that they cannot 
 be mistaken by the merest novice, should ever be undertaken until all 
 or as much refractive error as possible has been expunged. 
 
 If the observer be an adept in the art of ophthalinoscopy, and 
 knows so well how to handle the instrument that it offers no inconven- 
 ience in any way, or even if its use iu this particular jconnection is 
 repeated sufficiently often until all technique has been thoroughly 
 3
 
 34- Important Ophthalmic Methods Employed for the 
 
 mastered, the presence of muscular deviation may often be objectively 
 decided. To do such work properly, the patient is to be seated in the 
 ordinary ophthalmoscopic position. The light is to be placed directly 
 over and back of his head. The observer is to stand directly in front 
 of the patient and to face him. The patient should now be made to 
 gaze steadily at the sight-hole of the instrument or the forehead of the 
 observer. The observer is to gaze alternately at the two eyes of the 
 patient and study the relative situations of the bright light-reflex upon 
 the patient's cornese. The feeblest nystagmic motions may ofttimes 
 be brought to view by recourse to one of these methods. If the mirror 
 be not at hand, a candle-flame so shaded from the observer that it does 
 not interfere with the sight of the patient's cornese, may be substituted. 
 This latter plan, although somewhat more difficult and necessitative of 
 more practice, has several times served the writer at the bedside. 
 
 A spasmodic action of the superior elevator muscle of the upper 
 lid, known as Abadie's sign, may, at times, be distinguished in cases 
 of Basedow's disease. Lessening of the palpebral fissure, described 
 by Jacobson as sympathetic ptosis and probably due to paralysis of the 
 sympathetic, may appear during the course of posterior spinal sclerosis. 
 Imperfect action of the orbicularis muscle with pupillary movements 
 dependent upon a minor degree of facial palsy, which has been called 
 attention to by Berger as appearing in the same disease, should be 
 sought for in suspected cases. 
 
 At times, in exophthalmic goitre, the upper lids lag when the
 
 Recognition of Peripheral and Central Nerve Disease. 35 
 
 eyes are made to direct their gaze downward. This, known as the 
 "von Grafe sign," has, in the hands of the writer, been the easiest 
 recognized, whilst the patient is made to lie flat upon his back, with his 
 head slightly elevated and inclined forward upon a firm, hard pillow. 
 While the patient is in this position, he should be made to gaze with 
 his two eyes at the observer's finger-tip, which is to be held at about 
 seventy centimetres directly above the patient's face. The observer 
 is then to slowly move his finger in a curvilinear direction towards the 
 patient's breast. If the sign be present, the upper lids will lag, whilst 
 the eyeballs will follow the finger. Dalrymple's sign, or Stellwag's 
 symptom, which consists in an abnormal widening of the fissure be- 
 tween the lids, can often be seen in the same disease. 
 
 In some instances, a valuable clinical guide as to the degree of 
 smoothness and evenness of the movements of the extra- ocular mus- 
 cles through their tendinous sheaths and coverings, can be obtained by 
 the employment of auscultation. The writer has sometimes felt that he 
 has thus added an additional diagnostic factor in so-called muscular 
 paralyses that later have been found to have been mere mechanical 
 impediments to muscle-action. This he has several times observed in 
 cases of rheumatism and gout. 
 
 SUBJECTIVE STUDY OF MOTOR CONDITIONS. 
 
 The last grouping of studies of the motor series of ocular symptoms 
 (the subjective motor) is in reality the most vague, and frequently the
 
 36 Important Ophthalmic Methods Employed for the 
 
 most confusing. Here, not only must the answers depend upon the 
 patient's assertions, which often are the sequences of incomprehensible 
 questions to his uneducated mind, but frequently, especially in the 
 seriously ill and the mentally unfit, the apparent results are useless and 
 valueless. When properly obtained, however, and fortunately, as a 
 rule, in subjects whose disease is in its very incipiency, the results are 
 most valuable. Brief training of the patient with a couple of the pro- 
 cedures, and explanation of what is to be expected in a few of the 
 easiest methods, before any attempts at examination are made, have, in 
 the writer's experience, saved much subsequent useless labor upon his 
 part, and given answers that have been eminently satisfactory. 
 
 Commencing with the easiest and the most easily comprehended, 
 the plan for the determination of the disturbances of the extra-ocular 
 muscular groupings will be taken first. The muscles should be tested 
 both when they are used to fix the eyes upon near and when they are 
 made to have them gaze upon distant objects. In every instance, care 
 must be taken to note the circumstances under which the test is being 
 performed. Taking the study of the deviations where the eyes are 
 gazing at a distance first, the simplest and easiest plan to render any 
 disturbance apparent, and one which can be accomplished without the 
 employment of any delicate or complicate apparatus, is to have the 
 patient placed in a darkened room. He should then be made to gaze 
 at a minute point of light, situated at about five metres' distance from 
 his eyes and upon a level with them. A ten-degree prism, base up or
 
 Recognition of Peripheral and Central Nerve Disease. 37 
 
 down, is next to be placed before one of his eyes. Preferably, as a 
 routine, the left eye should be the one chosen. The relative positions 
 of the false light thus produced and the true one are then to be ascer- 
 tained. For example, if the prism be placed base up before the left 
 eye, the false image thus produced and seen by the left eye, will be 
 thrown below the true light. Should the inferiorly-situated false light 
 be also thrown to the right, there is, by reason of the left false light 
 having been crossed over to the right of the true right light, a condi- 
 tion known as crossed or heteronymous diplopia. This shows that the 
 patient has either an enervation of the left internus muscle or a spas- 
 modic contraction of the right externus muscle. So, similarly, with 
 any series of muscles, the position of the false image as compared with 
 the true one will always give immediate and almost certain answer as 
 to the character of the fault and the determination of the muscle that 
 is disturbed. These obtained, the degree of apparent variation can 
 then be readily determined by the superposition of increasing strengths 
 of correcting prisms with their apices placed towards the supposed 
 affected muscles. 
 
 Should the false light, when the prism is placed either base up or 
 down before one eye, appear upon the side towards the eye before 
 which the prism is placed, the double vision, or diplopia, as it is termed, 
 would then be known as homonymous. If, under the same circum- 
 stances, the two lights be situated immediately in vertical line, there is 
 said to be orthophoria or perfect binocular equilibrium in that meridian.
 
 38 Important Ophthalmic Methods Employed for the 
 
 If desired, a gauged card can be substituted for the correcting prisms, 
 and the amount of apparent deviation can be readily designated by the 
 patient. To assist in the determination of the relative positions of the 
 two images, the true one can be made to appear as " red" to the patient 
 by placing a piece of plain red glass before the eye that has not any 
 prism before it, thus more readily differentiating it from the false one 
 that has been produced by the prism -bearing eye. 
 
 In vertical deviation obtained by horizontally-placed prisms, the 
 prism-strengths must be necessarily greatly increased. This is so, by 
 reason of the preponderant powers of the lateral muscle-groupings over 
 the vertical muscles to overcome stronger prisms. In this series of 
 experiments, the faulty findings are to be estimated by vertically-placed 
 correcting prisms. If, during such experiments, a tendency for vertical 
 deviation of one of the visual lines be found, hyperphoria is said to 
 exist. 
 
 Another rough and ready test for the determination of muscle- 
 balance that is peculiarly applicable to the sick-room is what is known 
 by Duane as the parallax-test. After having placed the patient and a 
 distant light upon a proper level, he is to be requested to alternately 
 expose the two eyes whilst he endeavors to steadfastly gaze at the 
 light. If muscle-balance exists, the right and the left image of the 
 light will not apparently undergo any movement. If any muscular 
 deviation be present, the images of the lights will appear to jump into 
 a new position the moment that the covered eye is exposed. If desired,
 
 Recognition of Peripheral and Central Nerve Disease. 39 
 
 the degree of muscle disturbance can be easily estimated in this test by 
 means of correcting prisms. 
 
 With properly-constructed apparatus, the tests for the determina- 
 tion of muscle-balance become more beautiful and more certain. Com- 
 mencing with the simplest, the glass-rod test of Maddox, much 
 important data, especially from previously instructed and intelligent 
 subjects, can be obtained. The contrivance essentially consists of one 
 or more short cylinders of clear glass that distort the image of the light 
 into one or more lines that are situated at right angles to the direction 
 of the placing of the rod. The image of the lines is so different in out- 
 line and shape from the untransformed image of the light as seen with 
 the opposite naked eye, that it cannot be confounded or fused with the 
 undisturbed image of the fellow eye. Consequently, if no impulse for 
 fusion exists, the muscles of each eye will assume their individual state 
 of equilibrium. This is immediately shown by the relative positions of 
 the projections of the two series of images. Should any deviation 
 exist, its angle and its degree can easily be estimated, just as in the 
 previous test, by the addition of the prismatic strengths that are neces- 
 sary to superimpose the lines exactly upon the untransformed candle- 
 flame. 
 
 If the patient can be seen at a consultation room, where more deli- 
 cate contrivances can be employed, some one of the better grade pho- 
 rometers and revolving prisms, such as Prince's, Risley's, Jackson's, or 
 Stevens's, may be used. Where greater delicacy or where scientific
 
 40 Important Ophthalmic Methods Employed for the 
 
 accuracy is necessary, some more complex and more expensive contri- 
 vance, such as Brayton's optomyometer, may become useful. 
 
 The above-mentioned simpler tests, when used in their various 
 forms by an accurate observer, can hardly fail to elicit adequate data 
 as to almost all forms of muscle discrepancy, after sufficient repetition 
 and due explanation have been given to the patient. In many of the 
 grosser and more marked cases, the mere superposition of a plain red 
 glass before one of the eyes will be all that is necessary to study the 
 kind and the degree of diplopia. 
 
 In numerous instances, the writer has found that it is a good plan 
 to estimate one faulty meridian, as, for example, the horizontal, and 
 then, after this has been corrected, to search for any disturbance in the 
 opposite meridian and to estimate this. By this plan, the combined 
 correction frequently evinces a less difference of necessary strengths in 
 each of the two meridians than would be found were they to be sepa- 
 rately estimated. This should always be remembered, as it is a plan of 
 procedure that may be of the utmost etiological importance and even 
 of subsequent therapeutic value in special cases under study. 
 
 Another method that may at times be adopted, is to estimate the 
 amount of prism-deviation that the different extra-ocular muscles can 
 overcome. This is done by having the patient look at a distant light 
 with his two eyes, and then substituting stronger and stronger prisms 
 before one eye with their apices pointed towards the muscle of that eye 
 which is desired to be studied, until double vision is complained of.
 
 Recognition of Peripheral and Central Nerve Disease. 41 
 
 As a rough guide, the internal rectus muscles are said to generally 
 overcome about forty to fifty degrees of prism strength ; the external 
 rectus muscles about eight degrees ; the inferior rectus muscles about 
 four degrees ; and the superior rectus muscles about three degrees. 
 
 In all cases, the subjective determination of the degree of the 
 power of the ciliary muscle, thus evidencing the amount of consequent 
 lenticular action, is necessary. To do this properly, one eye should be 
 tried at a time. It is always best to commence with the supposed 
 more affected one. A series of small test-words are to be first approxi- 
 mated so closely to the patient's face that he cannot recognize any of 
 the type. By now slowly moving the card away from the eye, the dis- 
 tance of the point of the first correct naming of the letters or spelling of 
 the smallest words upon the card away from the eye is to be noted in 
 centimetres. This distance or measurement gives the near point, or 
 punctum proximum (p.p.), as it is termed. This represents the utmost 
 strength of the accommodative or focussing apparatus of the eye, and 
 shows the amount of action of the ciliary muscle. After this has been 
 registered, the card of type is to be removed beyond the limit of dis- 
 tinct vision for the same size of letters that has been used to obtain 
 the near point. The letters are then to be slowly approached towards 
 the patient's eye until another similarly-sized word or combination of 
 letters is correctly read. This gives the farthest point, or the punctum 
 remotum (p.r.;. The two series of findings are to be noted in the fol- 
 lowing manner: for example, "Ace. (accommodation) = type 0.50
 
 42 Important Ophthalmic Methods Employed for the 
 
 D (the size of one series of letters), 20-35 c.m. (centimetres)." Where 
 presbyopia is supposed to exist, or where there are high and extreme 
 degrees of ametropia, the superposition of correcting lenses, taking 
 care to specify them in the notings, should be employed to enable the 
 patient to read the test-words. 
 
 In addition to these four varieties of procedures for the determina- 
 tion of the motor and sensory symptoms of the visual apparatus, the 
 observer should never fail to obtain a clear and a concise history of any 
 pre-existing and present ocular symptoms. A brief record of the gross 
 objective condition of the organ should be noted. The deeply-seated 
 and the more superficial vascularity of the sclera and overlying con- 
 junctiva should be studied. Fatty degeneration areas around the 
 periphery of the cornea should be searched for. The state of the 
 lacrymal apparatus should be determined. Marks of inflammatory 
 thickenings, and the degree of intra-ocular tension, should both be 
 recorded. 
 
 If to these the relative prominence of the eyes be gauged, and 
 palpation and auscultation be practised for the detection of orbital 
 bruit, the work will be more complete. At times, it must be remem- 
 bered that patients may either intentionally or unwittingly feign cer- 
 tain ocular symptoms. The determination of the truth or falsity of 
 their assertions can be accomplished by experiments and procedures 
 which are intended to either actually deceive or confuse the patient. 
 Plans of all kinds, dependent upon the ingenuity of the examiner, 
 can be tried for this class of subjects.
 
 Recognition of Peripheral and Central Nerve Disease. 43 
 
 In parting, the writer can give no better advice to the reader 
 than to study every ocular symptom that may appear of importance to 
 the elucidation of the cause of any related neural disturbance. The 
 examiner should understand that it is the entire grouping of the ocular 
 conditions that alone can furnish proper data. This must be done 
 repeatedly and sufficiently often to allow an understanding of the course 
 taken by the symptoms, and to formulate some generalization as to their 
 significance. In fact, if in all of his work the reader should con- 
 stantly employ the most careful and painstaking technique, and exer- 
 cise proper judgment as to the meaning of the findings, he will soon 
 realize that the reputation and certainty of his results will far more 
 than repay him for his trouble and his care.
 
 IKDBX. 
 
 Abadie's sign, 34. 
 
 Acommodation, fundus-reflex test in de- 
 " termination of, 30. 
 
 " iris response to, 26. 
 
 Anesthetic areas, recognition of, 19. 
 Arcus senilis, 42. 
 Ataxic movements of exterior muscles 
 
 of eyes, 32. 
 Auscultation, 42. 
 Axis of pupil, 23. 
 
 Bellanuinoff's method, n. 
 Berger's sign, 34. 
 
 Candle-field, 21. 
 
 Catoptric test, 29. 
 
 Central vision for form, determination 
 
 of, 14. 
 Ciliary muscle, determination of power 
 
 of, 41. 
 Color, direct vision for, 17. 
 
 " perception, averages of, 17. 
 
 " " subnormal, 17. 
 
 Color perception, methods of determi- 
 nation of, 18. 
 
 Convergence, iris reaction to, 27. 
 Corneal loupe, 13. 
 
 Dalrymple's sign, 35. 
 Davidson's sign, 13. 
 Designation of visual acuity, 15. 
 Diplopia, 37. 
 Double vision, 31. 
 
 Equilibrium of irides, 23. 
 
 Esthesiometry, 22. 
 
 Evenness of movement of extra-ocular 
 muscles, 35. 
 
 Extrinsic muscles of eyes, determina- 
 tion of movement of, 31. 
 
 Extrinsic muscles of eyes, study of equi- 
 librium of, 31. 
 
 Facial expression, abnormalities of, 31. 
 Far-point, 41. 
 Fluorescin, value of, 13. 
 
 45
 
 46 
 
 Index. 
 
 Focal illumination, 12. 
 Fundus-reflex, 7. 
 
 Gavel's sign, 13. 
 
 Glass-rod test, 39. 
 
 von Grafe's sign, 35. 
 
 Groupings of ophthalmic symptoms, 5. 
 
 Haab's plates, n. 
 Hemianopic iris inaction sign, 27. 
 Heteronymous diplopia, 37. 
 Heterophoria, 36. 
 Holmgren's method, 18. 
 Homonymous diplopia, 37. 
 Hyperphoria, 38. 
 
 Illumination in ophthalmoscopy, 7. 
 
 Indirect vision, 19. 
 
 Intraocular tension, 42. 
 
 Iris movement, determination of, 25. 
 
 Jacobson's sign, 34. 
 Knies pupil-symptom, 29. 
 
 Lacrymal apparatus, state of, 42. 
 Lateral illumination, 12. 
 Light-perception, 16. 
 Light-projection, field of, 21. 
 Light-stimulus, iris response to, 25. 
 
 Maddox rod, 39. 
 Malingering, 42. 
 Minimum visibility, angle of, 14. 
 Motor conditions, objective study of, 23. 
 " subjective study of, 35. 
 Muscular deviation determined by oph- 
 thalmoscope, 33. 
 
 Near-point, 41. 
 
 Nystagmus, determination of, 34. 
 
 Oblique illumination, 12. 
 Ophthalmoscopy, 6. 
 
 " direct method of, 8. 
 
 " indirect method of, 9. 
 
 " inverted plan of, 9. 
 
 1 ' magnification of image in, 8. 
 
 " sketching in, n. 
 
 " upright method of, 8. 
 Optic disc, apparent magnitude of, 8. 
 
 " " real size of, 8. 
 Optomyometer, 40. 
 Optotypi, 15. 
 Orthophoria, 37. 
 Orthoscopic study, n. 
 
 Palpation, 22, 42. 
 Parallax-test, 38.
 
 Index. 
 
 Paresthetic areas, recognition of, 19. 
 Parrot's sign, 27. 
 Perimetry, 19. 
 
 " methods of, 20. 
 Peripheral vision, 19. 
 Phorometers, 39. 
 Phosphenes, 19. 
 Power of accommodation, 41. 
 Presbyopia, 42. 
 Prominence of eyes, 42. 
 Punctum proximum, 41. 
 
 " remotum, 41. 
 Pupillometer, 23. 
 
 Quantitative field for light perception, 21. 
 
 Region of accommodation, 41. 
 Revolving prisms, 39. 
 Rotation of eye, 32. 
 
 Scotomata, determination of, 20. 
 Sensory symptoms, objective determi- 
 nation of, 6. 
 
 Sensory symptoms, subjective determi- 
 nation of, 14. 
 
 Size of pupil, 24. 
 
 Smoothness of movement of extraocular 
 muscles, 35. 
 
 Spectroscopic examination, 14. 
 
 Stellwag's symptom, 35. 
 
 Strabismometer, 31. 
 
 Strength of accommodation, 41. 
 
 Sympathetic ptosis, 34. 
 
 Tenderness, ciliary, 22. 
 Test-types, 15. 
 Thermometry, 22. 
 Tiffany's sketching blanks, n. 
 Transillumination, 13. 
 
 Vascularity of sclera and conjunctiva, 
 42. 
 
 Wernicke's sign, 27.
 
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