THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 LOS ANGELES 
 
 GIFT OF 
 
 SAN FRANCISCO 
 COUNTY MEDICAL SOCIETY
 
 HETEROPHORIAS AND 
 INSUFFICIENCIES 
 
 A CLINICAL STUDY 
 
 BY 
 
 H. H. SEABROOK, M.D., 
 
 SURGEON, NEW YORK EYE AND EAR INFIRMARY, ETC. 
 
 Cbc Ikmchcrbocfccr press 
 1900
 
 Library 
 
 WtO 
 
 HETEROPHORIAS AND 
 INSUFFICIENCIES 
 
 A CLINICAL STUDY. 
 
 CHAPTER I. 
 
 GENERAL CONSIDERATIONS AND METHODS OF 
 TESTING. 
 
 TH E class of cases to be considered here has been 
 recognized as having had an existence since 
 \^ the dawn of modern ophthalmology. Von Graefe at- 
 tempted to solve the problems they presented, and 
 : although he furnished some valuable ideas for his 
 : successors to work upon, his knowledge upon the 
 tf subject would be a poor equipment for an ophthal- 
 .* mologist of to-day. Donders saw the fallacies of the 
 work being done in this field, solved in general 
 Jfc terms the problem of accommodative asthenopia, 
 
 624398
 
 2 Hctcrophorias and Insufficiencies. 
 
 and found that " as soon as insufficiency of the in- 
 ternal or external recti muscles in binocular vision 
 threatens to give rise to muscular asthenopia, it is of 
 importance that the mutual distance of the glasses 
 should not aggravate this but rather counteract 
 it." If spherical glasses are insufficient, we are to 
 combine with prisms or operate according to 
 Von Graefe. There is agreement with Helmholtz's 
 statement that displacement of glasses in a vertical 
 direction causes more asthenopia than the same 
 amount of lateral displacement. Except for the op- 
 erative method indicated, the statements here made 
 are entirely sound, but cannot be said to suffer from 
 over-elaboration ; they seem, however, sufficient to 
 more than cover what is usually done for muscular 
 asthenopia to-day in practice upon the European 
 continent. In England signs of interest began to be 
 manifested regarding these cases over fifteen years 
 ago, and thanks to the work of Maddox and others 
 many principles of value were evolved. Previous to 
 this, Stevens in America had succeeded in attracting 
 attention by means of his work, his highly enthusi- 
 astic followers, and his bitter opponents. A portion 
 of his nomenclature came into general use, and is 
 here followed. Orthophoria, muscular balance ; het- 
 erophoria, tendency to deviation ; esophoria, conver- 
 gence tendency ; exophoria, divergence tendency ; 
 hyperphoria, upward tendency. These terms were
 
 A Clinical Study. 3 
 
 taken to be equivalent to and supersede the old ones 
 of insufficiency of the interni and externi, even 
 Duane, whose masterly classification of these condi- 
 tions has earned deserved recognition, taking this 
 view ; yet heterophoria means merely a tendency of 
 the fixation lines away from the object of fixation, 
 while insufficiency means lack of power. The old 
 terms for exophoria and esophoria were dynamical 
 divergence and convergence. It is the intention of 
 the writer to show that certain forms of heterophoria 
 may be due to errors of refraction or other optical 
 defects, others to habit, others to the nervous sys- 
 tem, and others still to muscular spasm, excess, or 
 insufficiency. Much has been written upon this 
 subject in addition to that so briefly mentioned, 
 some of it of value, and the writer proposes to treat 
 all of the authors in the most impartial manner, as 
 he appropriates their ideas whenever he can make 
 use of them, without regard to their source. He has 
 no instruments to exploit, no special method of treat- 
 ment to push, no new general disease which he has 
 cured through the eye muscles. If, in spite of this, 
 an original idea or so should creep in among the 
 others, anybody is welcome to use it as his own. 
 
 In discussing the question of correcting the refrac- 
 tion except as incidental to the treatment of muscu- 
 lar anomalies, there is of course no intention to 
 belittle this very important consideration in the
 
 4 Heterophorias and Insufficiencies. 
 
 treatment of eye strain. Important as this branch 
 of the subject undoubtedly is, correction of the re- 
 fraction may be carried to the point of absurdity. 
 When a patient with undoubted exophoria and in- 
 sufficiency of the interni complains of severe head- 
 ache, dizziness and nausea, excited or increased 
 when convergence is attempted, it is perfectly silly 
 to correct .12 or .25 D. of hypermetropia in such 
 eyes, and yet many have done such things. 
 
 In studying the effect of correction of the refrac- 
 tion upon the ocular muscles, it is absolutely neces- 
 sary to separate this secondary effect of glasses from 
 the prismatic effect of a decentred lens. In order 
 that the optical centre of a lens may be found, the 
 lens should be held in front of a horizontal line in 
 such a position that the line is continuous through 
 the glass without deviation at either edge. The 
 position of this line is then marked upon the glass 
 and the process repeated at right angles to the first 
 position ; the lines cross at the optical centre and 
 show in a sphero-cylindrical lens the axis of the cyl- 
 inder and the maximum curve at right angles to it. 
 In a simple cylinder the axis only can be found, as 
 there is no prismatic displacement of a line at right 
 angles to the axis ; a cylinder with horizontal axis 
 cannot be decentred horizontally, and similarly with 
 the axis in other meridians. Two lines crossing at 
 right angles may be used to find the optical centre
 
 A Clinical Study. 5 
 
 instead of the above-described method, or the lens 
 may be held in front of an object, as a candle flame, 
 in such a position that the reflected images from the 
 surfaces of the glass are superimposed, when the po- 
 sition of the images shows the optical centre. The 
 last method may be used for rapid verification 
 under certain circumstances, but I prefer the first for 
 several reasons. The base and apex of a prism are 
 marked by a line continuous through the glass, just 
 as the axis of a cylinder is. When the cylinder is 
 revolved upon its centre, we notice a peculiarity of 
 prismatic action due to the varying curves, which re- 
 sults in torsion of lines oblique to the axis, being 
 most marked at an inclination of 45. While there 
 are causes for the distortion of objects caused by 
 glasses other than simple prismatic effect, yet this 
 prismatic action of the transparent cylinder has not 
 only an important bearing upon the asthenopia pro- 
 duced by cylindrical lenses, but, taken in connection 
 with other prismatic effects of curved surfaces and 
 applied to the human eye with its frequently de- 
 centred astigmatic refractive media, it throws an 
 entirely new light upon many observations in physio- 
 logical optics and opens up a new field in the ex- 
 planation of muscular anomalies. A very plausible 
 connection could be shown between apparent diver- 
 gence and convergence, the decentred biconvex 
 lens system between the anterior corneal surface and
 
 6 Heterophorias and Insufficiencies. 
 
 the posterior surface of the crystalline lens, and con- 
 vergent and divergent squint ; its bearing upon the 
 subject in hand will be shown later. 
 
 The primary position of a pair of glasses in front 
 of the eyes when it is desired to study their effects 
 upon the ocular muscles is with the optical centres 
 in the lines of fixation. This position can be ob- 
 tained with considerable accuracy by sighting ; that 
 is, by making each examined eye fix the examiner's, 
 when the optical centre of the glass is placed in the 
 line which seems to correspond to the line of fixation 
 of the former and the line of vision of the latter. If 
 there is a question as to the correctness of this, discs 
 with vertical stenopaeic slits may be placed in an 
 adjustable frame, and the distance between their 
 centres measured when both eyes can see through 
 the slits at the same time. This distance between 
 the optical centres (o. c.) should not be confounded 
 with the distance between the geometrical centres 
 of glasses to be worn (p. d.), which should come op- 
 posite the pupils for the sake of appearance and 
 because there will be less annoyance to the patient 
 from the refraction and reflection at the edges of the 
 lenses when they are symmetrical with the pupil. 
 
 The prismatic effect of a decentred spherical lens 
 is obtained by multiplying the distance between the 
 optical and geometrical centres, taken in centimetres 
 and tenths, by the dioptric strength of the lens.
 
 A Clinical Study. ^ 
 
 Thus, a 2 D. lens decentred 3 mm. equals a .6 D. 
 prism, 2. X -3 = .6. In a pair of glasses the difference 
 between the primary and secondary position is taken. 
 Thus, if the glasses are 60 mm. o. c., and the lines of 
 fixation cut them 57 mm. apart, the prismatic action 
 of a pair of 2 D. lenses is .6 D., one half in each 
 eye. If the number of centimetres of decentring 
 to produce a certain prism is desired, the formula 
 is v -~ = cms., in tenths. The base of the prism is, of 
 course, toward the periphery of a concave lens, 
 toward the centre of a convex one. If the curve of 
 the lens and the position of the line of fixation are 
 kept in mind, or put on paper, there can be no con- 
 fusion. In a cylindrical lens the number of dioptrics 
 can be found in any direction by means of the lens 
 measure and prismatic action then figured as for a 
 sphere. 
 
 This easy method of figuring the prismatic action 
 of a decentred lens is one of the merits of the prism 
 dioptry system proposed by Mr. Charles Prentice, a 
 layman, and adopted by many manufacturing opti- 
 cians throughout the country on account of its sim- 
 plicity and accuracy when applied to the manufacture 
 of prisms. I began to use it soon after it was first 
 suggested. The unit is the prismatic power which 
 causes I cm. of light deviation at I metre. A lens of 
 i D. refractive power decentred I cm. = I P. D. 
 (A D. or D.), i.X i.= i. The best scale I know for
 
 8 Heterophorias and Insufficiencies. 
 
 measuring prisms in this system is that of Dr. Ziegler. 
 I propose to speak of heterophorias in terms of prism 
 dioptrics, just as we speak of hypermetropia and 
 myopia in terms of the correcting glass. It is not 
 necessary in either case to add dioptrics or D. to the 
 figures in decimals which designate the strength of 
 the glasses, and it will generally be omitted in the 
 following pages. 
 
 There are a few things regarding the action of 
 prisms necessary to remember in clinical work. 
 Prisms beyond a certain strength can not be used in 
 correcting anomalies of the ocular muscles for several 
 reasons, some relating to the effect upon the muscu- 
 lar action, others to mental effect upon the patient, 
 and yet others to distortion due to prismatic astig- 
 matism from the varying ratio between the angles of 
 incidence and refraction. There is a position of 
 minimum deviation in which a ray of light passes 
 symmetrically through a prism and other rays suffer 
 greater deflection. In testing for an object in the 
 direction of the line of fixation, prisms should be 
 placed with the surface toward the eye perpendicu- 
 lar to that line, in order to secure as nearly as possi- 
 ble the position of minimum deviation. The position 
 of the prism may assume some importance in the case 
 of a vertical prism, as, if this is placed in the posi- 
 tion of minimum deviation for distance, its action is 
 stronger for near points, the increase amounting to
 
 A Clinical Study. 9 
 
 about one-tenth of its strength for the nearest point 
 at which the eyes are likely to be used. 
 
 As will be shown later, patients with inefficient 
 ocular muscles do not bear prisms as well as those 
 with strong muscular action ; stronger prisms may 
 be worn base in for near work than base out for dis- 
 tance, and with axis horizontal than vertical, and a 
 3 D. prism over each eye is about the limit of 
 strength under favorable conditions. 
 
 Secondary images due to reflection from the sur- 
 faces of the glass cause more annoyance in glasses 
 containing prisms than in those without them, but 
 the colors due to dispersion, diminution in size and 
 change of shape of an object, occur to a considerable 
 extent only when a strong prism is placed before 
 one eye, as in testing muscular power, or at least are 
 remarked upon by patients mostly under this con- 
 dition. 
 
 The eye moves toward the apex of a prism in or- 
 der to overcome the deviation of rays of light 
 toward the base, and when it is unable to do this 
 diplopia results, with the image from the eye before 
 which the prism is placed in the direction of the 
 apex. The action of the interni in overcoming 
 prisms base out is called adduction, the externi with 
 prisms base in, abduction. These terms are easily 
 confounded, and the mind becomes so confused and 
 fatigued by them that I propose to use instead the
 
 io Heterophorias and Insufficiencies. 
 
 terms convergence and divergence. This can cause 
 no confusion as the amount is always given in 
 terms of measurement. P. D's of convergence and 
 divergence cannot possibly be confounded with 
 metre-angles or degrees, and those who use the term 
 degrees, except as applied to perimetric measure- 
 ments, cannot be cast into any more confusion by 
 the innovation than that under which they now are 
 laboring. 
 
 There is one point upon which there is agreement 
 among all investigators in this direction : it is that 
 abduction or divergence for distance with well bal- 
 anced and strong eye muscles should be 7. or 8- 
 [These figures are the same whether the old degree 
 system, dioptry, or centrad is used. It is beside the 
 purpose of this treatise to argue regarding these sys- 
 tems and the new system in degrees of Landolt. 
 Whatever its demerits, the dioptric system has been 
 (unofficially) adopted.] The student who finds that 
 his investigations seem to contradict this standard 
 for divergence should doubt the accuracy of his ob- 
 servations ; with an abducting prism the double 
 images may easily pass unnoticed when they first 
 appear and then suddenly be observed a consider- 
 able distance apart at the time a stronger prism than 
 represents divergence is being used. In such a case 
 prisms of gradually decreasing strength should be 
 used until single vision results, then gradually
 
 A Clinical Study. 1 1 
 
 increased again. After some experience the exam- 
 iner will begin with the prism which is to his mind 
 most likely to represent the divergence to be ex- 
 pected from the examinations previously made of the 
 refraction and muscular balance. Until this experi- 
 ence is acquired it is well to start with a prism of 6., 
 7., 8., or 9. It has already been said that divergence 
 which varies from 7. or 8. may be considered ab- 
 normal. A certain number of cases show but 6., in 
 which the only criticism is that divergence and con- 
 vergence are neither of them at their best. In other 
 words, amplitude of convergence is slightly below 
 the standard, and there is no other defect. An oc- 
 casional case may be found in which the amplitude 
 of convergence is so great that divergence of 9. or 
 even 10. is equalized by correspondingly strong con- 
 vergence and muscular balance is good. Such cases 
 are liable to develop exophoria later, but for the 
 time being are sometimes to be complimented upon 
 their strong ocular muscles. Cases like this are 
 perhaps not so infrequent as would appear from 
 our histories. Persons with ocular muscles of that 
 sort would not be apt to be weak or neurasthenic, 
 and would hardly be bothered by trivial errors of 
 refraction. 
 
 When it is said that divergence for distant vision 
 should be 7. or 8., what is really meant is that this is 
 what should be shown by the candle test at a
 
 1 2 Heterophorias and Insufficiencies. 
 
 distance of about twenty feet, which is the usual test. 
 It is in reality about I. more than the actual power 
 of divergence for infinity, as I D. of convergence is 
 necessary for binocular fixation at twenty feet. It 
 is fortunate that there should be such a definite 
 standard of divergence for distance, since the power 
 of divergence for distant vision is an important mat- 
 ter ; divergence power for any near point theoretic- 
 ally would equal the amount required to bring the 
 lines of fixation parallel, added to that which is still 
 possible with parallel fixation lines when the eyes 
 are adjusted for infinity. This total is obscured in 
 making a test at a near point by the accommodative 
 convergence and certain other factors, but while 
 neither so definite nor important as divergence ob- 
 tained for distance, it is a help in comparing the 
 variations of the muscular action for near and far. 
 At about thirteen inches (taken as the average read- 
 ing distance) the prism test shows generally some 6 
 to 8 D's more of divergence than is shown by the 
 test at twenty feet, the difference being less than 
 this in cases of esophoria without insufficiency of 
 convergence, greater in some cases of exophoria. 
 Where divergence at thirteen inches is 18. or more, 
 insufficiency of convergence power at that distance 
 is almost sure to be present. 
 
 Convergence power for near work is of far more 
 importance than it is for distance, which is also
 
 A Clinical Study. 13 
 
 fortunate, as the prism test for convergence at a dis- 
 tance is very variable. This variability is due mostly 
 to the much greater difficulty some persons have 
 of disassociating convergence and accommodation 
 than others. If the only precaution taken in making 
 the test is that of dividing the prisms between the 
 examined eyes (a prism over one eye not only causes 
 dissimilar images but often convergence in the 
 armed eye alone, the other fixing), the proportion 
 between convergence and divergence in eyes with 
 orthophoria is apt to be as low as three to one. Con- 
 vergence 1 8., divergence 6. is about the limit for use- 
 ful ocular muscles on the one hand, while 70. versus 
 10. or even more can in rare instances be found 
 among the strong muscles. 
 
 Convergence does not represent the strength of the 
 interni alone, but the nervous energy put into them 
 as well. In testing this power, being of too impa- 
 tient a nature to wait for prism exercises or other 
 slow methods, I have my patients fix a finger, or a 
 lead pencil, which is gradually approached while the 
 eyes are armed with converging prisms, and often 
 with the exclamation, " Oh, that is what you want me 
 to do," they proceed to converge at distance at least 
 half as much again as they had succeeded in doing 
 but a moment before. The rapidity and simplicity 
 of this will absolutely prevent its acceptance as a 
 cure, so I shall not elevate it to the dignity of a
 
 14 Heterophorias and Insufficiencies. 
 
 method by giving it a name, as the principle itself is 
 already in use under many high-sounding titles. 
 
 A moment's reflection will show anyone that the 
 prism test at distance does not necessarily represent 
 the real convergence power as shown by the near 
 point for convergence. For the latter test I use a lead 
 pencil or a penholder, as being an object which is 
 always at hand during an examination, necessitates 
 accommodation on the part of the patient in order 
 that it shall be clearly seen, and allows the examiner 
 to watch the action of the eyes without distracting 
 his attention. The ease with which convergence for 
 the near point is accomplished, and the steadiness 
 with which the eyes hold an object, are of more im- 
 portance than the exact measure of its distance from 
 the eyes, and the sensations produced by this mus- 
 cular action, with the attitude of the patient regard- 
 ing them, are valuable diagnostic indications. I 
 would, moreover, as soon trust my observation as to 
 when convergence is no longer possible as a patient's 
 statement regarding the production of diplopia. 
 Tests for the near point usually will show more 
 power of convergence than the prism test at distance, 
 because in the latter instance the convergence 
 without accommodation is an unwonted, as it is usu- 
 ally an unnecessary, accomplishment. Teaching a 
 patient how to converge with prisms is simply train- 
 ing for a test, and has something of the same relation
 
 A Clinical Study. 15 
 
 to a cure of weak convergence as training a sensitive 
 throat for the tongue depressor has to the treatment 
 of hypertrophied tonsils. 
 
 The near point of convergence varies with the 
 refraction and becomes more and more distant as 
 age advances and accommodation and the interni 
 become weaker. Undoubtedly valuable as the test 
 for the near point of convergence may be, I confine 
 my use of it mostly to certain purposes already 
 mentioned, and as a check upon other tests. Thus 
 if convergence with prisms for a distance seems 
 below normal, I should reject a diagnosis of insuffi- 
 ciency of the interni, or of excess of the externi, 
 if the same eyes showed easy and comfortable 
 convergence up to two inches or less from the 
 root of the nose, with or without the correction 
 of the refraction. The prism test for conver- 
 gence at the reading distance is unsatisfactory, 
 although some information may be gained thereby, 
 as in cases in which hyperphoria occurs only with 
 convergence. 
 
 Sursumduction, or upward movement of an eye, is 
 tested on the same principle as convergence and 
 divergence : right sursumduction with the prism base 
 down right eye, or base up left eye ; left sursumduc- 
 tion base down left eye, base up right eye. It is hardly 
 necessary to call attention to the necessity of verify- 
 ing the base apex line of the prism and having this
 
 1 6 Heterophorias and Insufficiencies. 
 
 axis exactly horizontal or vertical in the above 
 mentioned tests. 
 
 Although it has been convenient to consider here 
 the muscular strength as shown in divergence and 
 convergence before the muscular balance or tendency 
 to deviation, the latter should be tested before the 
 former and preferably after examination of the re- 
 fraction. The test for balance which is most time- 
 honored is that by which vertical prisms produce 
 diplopia, when if the images have a homonymous 
 or crossed position as regards each other the correct- 
 ing prism which brings them into equilibrium is con- 
 sidered the measure of the esophoria or exophoria. 
 This test should be made at a distant and near point, 
 first without, then with, the refraction corrected. I 
 give the conclusions for a near point based upon 
 tests at 13 inches, as this is the distance I have 
 chosen for years, although now satisfied that it is 
 somewhat too near for most cases. The near test 
 would be best taken at reading distance, which 
 varies in different individuals. 
 
 The test for equilibrium with prisms has been per- 
 fected, especially by Stevens, and has resulted in the 
 phorometer with its two prisms of 5 D's base in, 
 which can be rotated, after the test for vertical 
 equilibrium has been obtained, for the test of 
 the lateral tendency, and shows the amount and 
 nature of the deviation upon its anterior surface
 
 A Clinical Study. 1 7 
 
 in prism dioptrics when the images show equi- 
 librium. It thus gives the novice information 
 of the deviation with which he has to deal with 
 some certainty, as he can hardly turn the instru- 
 ment upside down or otherwise misplace it in 
 making a test. When the axis of the prism is hori- 
 zontal, if single vision still obtains it is a fair con- 
 clusion that divergence is excessive, and another 
 prism may be added in order to obtain the lateral 
 images, the prisms in the phorometer only being 
 rotated in obtaining the measurements. An arm 
 upon the instrument is very handy for getting the 
 muscular balance at a near point, although the test 
 object is more horizontal to the eyes than the position 
 of the other objects most often seen at this distance 
 in ordinary work. As a rule, deviations remain latent 
 with this test to an extent that they do not with the 
 rod test, although occasionally the reverse is true. 
 
 The Maddox glass rod, or series of rods, will pro- 
 duce a line of light at right angles to the axis when 
 placed before an eye. This test has the advantage of 
 indicating the fixing eye (the unarmed one) and al- 
 lows it to be changed at will by changing the rod from 
 one eye to the other. When the correcting prism 
 is obtained its amount and direction are patent, thus 
 saving the beginner in ophthalmology some mental 
 effort in ordering correcting prisms. When a devia- 
 tion has been corrected with a prism in one direction
 
 1 8 Heterophorias and Insufficiencies. 
 
 the rod test will show the effect upon the deviation 
 at right angles to it, a very important consideration 
 in certain instances, as when with a correcting prism 
 for hyperphoria we wish to test exophoria or eso- 
 phoria as compared to the same deviation before 
 the correction. The rod test also allows of an ex- 
 amination toward the periphery of the field more 
 accurate than that of the phorometer, when we 
 wish to see if the deviations are comitant, but is of 
 no definite use in testing for reading distance. I 
 can hardly see how either of these tests can be 
 dispensed with. 
 
 The old screen test, in which one eye is covered, 
 then uncovered, and its deviation noted while the 
 other fixes, was in my hands so contradictory and 
 unreliable long ago, that when Duane modified its 
 use by adding a subjective element, giving the paral- 
 lax test, I lacked sufficient confidence in the latter to 
 use it, in which I may be wrong. Maddox rejected 
 the double prism with bases meeting at the centre 
 for the rod test, and various attempts have been 
 made to revive its use for certain purposes, with but 
 little success. 
 
 Having attempted to indicate the methods of ex- 
 amination which were followed in obtaining the 
 clinical data here used, I shall treat the subject of 
 heterophorias under the following heads: Hyper- 
 phoria; Esophoria, first, the accommodative, second,
 
 A Clinical Study. 19 
 
 esophoria from habit, lastly, esophoria from insuffi- 
 ciency of the externi or excess of the interni; Exo- 
 phoria, accommodative and muscular; and lastly 
 Insufficiency of Convergence, Inefficiency of the Ocular 
 Muscles, or Neurasthenic Muscular Asthenopia. It 
 may be observed that this class of cases is not in- 
 tended to comprise, except as occasional reference 
 may occur, those which have spontaneous diplopia, 
 since I regard these as either cases of periodic squint, 
 paresis of an ocular muscle, or of an associated move- 
 ment ; neither are other cases of evident strabismus 
 without diplopia to be considered in detail. Although 
 in practice it is difficult to draw the dividing line, 
 it is primarily my desire to further definite knowl- 
 edge regarding a class of cases in which individual 
 muscles may of course be affected, yet the deviation 
 can only be demonstrated by the heterophoria 
 shown with appropriate tests. 
 
 It is lack of definite knowledge concerning devia- 
 tions of both eyes above or below the horizontal 
 plane, or inclinations of the physiological vertical 
 meridian, which prevents consideration of these sub- 
 jects here; at present, although the germs of ideas 
 may be working in the brains of investigators upon 
 these subjects, we can hardly accept information as 
 definite where the diagnosis depends upon unproven 
 points in physiology and optics and treatment con- 
 sists of muscular exercises with oblique prisms, or
 
 2O Heterophorias and Insufficiencies. 
 
 tenotomy of the upper half of one lateral muscle and 
 lower half of its opponent. Torsion will receive 
 some incidental consideration in dealing with muscu- 
 lar deviations connected with oblique astigmatism. 
 Before proceeding to the symptoms of the special 
 deviations to be considered, it seems well to draw 
 attention to certain signs of ocular asthenopia com- 
 mon to the different errors. They are mainly head- 
 ache, dizziness and sensations of nausea, pain in the 
 eyes, retinal asthenia or hyperesthesia, congestion 
 of the palpebral or ocular conjunctiva. Any of 
 these may be due to muscular anomalies; pain in the 
 eyeballs seems often to occur from nutritive disturb- 
 ances, as may conjunctival congestion, although the 
 latter is generally connected with chronic nasal 
 catarrh. Relief of conjunctival congestion by 
 glasses may be due to protection of the eyes from 
 dust and chemical rays of light, has occurred with 
 plane glasses, or ridiculously weak spherical lenses, 
 and is no proof of relief of eye strain. Asthenopic 
 symptoms sometimes disappear when conjunctivi- 
 tis is successfully treated. Temporal headache is 
 usually due to astigmatism, the pain being most 
 severe on the side of the functionally better eye, 
 this being in men the right when refraction and 
 vision are practically equal, because their habit of 
 "sighting" objects with this eye renders them 
 more " right eyed " than women. Next to eye
 
 A Clinical Study. 2 1 
 
 errors, tobacco and whiskey in men, uterine trouble 
 in women, are the most important factors in tem- 
 poral headache. Frontal headache, when dull, may 
 be due to errors of refraction, but if severe and per- 
 sistent suggests insufficiency of the interni, or dis- 
 ease of the frontal sinus. Supra-orbital neuralgia 
 with tenderness over the nerve is usually unilateral 
 and is best treated with quinine unless the pain is 
 severe, radiating and persistent, with much lacrima- 
 tion, when it should be referred to nasal obstruction, 
 ethmoidal disease, or disease of some other of the 
 accessory sinuses. In this latter condition there 
 may be ciliary pain and lowered intra-ocular tension. 
 A feeling of pressure over the top of the head 
 about the fronto-parietal suture is from anaemia, not 
 eye strain, and localized pain over one parietal pro- 
 tuberance is not an eye symptom, although its pres- 
 ence with accompanying tenderness is not a positive 
 diagnostic sign of tumor of the brain, as is sometimes 
 stated. Very severe headache with vomiting, com- 
 ing on suddenly in persons who have not been sub- 
 ject to headaches, should always be regarded with 
 suspicion, and if persistent, it will perhaps be neces- 
 sary for a diagnosis between beginning cerebral dis- 
 ease and some lesion of the digestive organs to wait 
 for further developments. 
 
 In " bilious attacks " there is sometimes paresis 
 of an ocular muscle or of an associated movement
 
 2 2 Heterophorias and Insufficiencies. 
 
 at the time of an attack which recurs with such 
 attacks for years, and just such conditions of the 
 muscles may occur and prove very misleading to the 
 oculist in cases of central disease of the nervous 
 system. Take, for instance, a case of recurrent 
 pachymeningitis in an early stage, with headache 
 and spasm of convergence from irritation of the con- 
 vergence centre, or some other muscular trouble 
 from central lesion which resembles some muscular 
 excess or insufficiency in which treatment usually 
 causes relief, and in such a case relief to the head- 
 ache follows treatment of the eye muscles. It is 
 hard to avoid mistakes in such cases, yet in them 
 mistakes are very awkward ; it weakens a man's local 
 influence as an authority on muscular asthenopia 
 when some of his medical neighbors have attended 
 autopsies upon the late subjects of some of his late 
 cures, and have not exercised that charity regarding 
 faulty diagnosis which seems so often to begin at 
 home. 
 
 Pain in the back of the neck, with dizziness and 
 nausea, should immediately excite suspicion of 
 heterophoria, or insufficiency of the ocular muscles. 
 Tenderness over the upper portion of the spine, or 
 the adjacent sensory nerves, does not argue against 
 this. Similar pain with or without general head- 
 ache has been known to occur in disease of the 
 sphenoidal and ethmoidal sinuses, is present in brain
 
 A Clinical Study. 23 
 
 disease and lesions of the upper portion of the spine, 
 and is given as a common symptom in nephritis, 
 gout, stomach, intestinal and liver diseases, and 
 especially in neurasthenia. In neurasthenia these 
 symptoms I am satisfied should usually be referred 
 to the eyes, and in particular to the ocular muscles. 
 In cases in which these symptoms are especially 
 dwelt upon as diagnostic of the general nervous con- 
 dition they are frequently helped by treatment of 
 eye strain, and I have myself sometimes in this 
 manner received credit for curing neurasthenia 
 through the eyes, although so far as I know I have 
 never seen a case in which I could positively and 
 justly claim any such cure. The same holds good 
 in other conditions; the so-called gouty headache, 
 and that of nephritis, may not uncommonly be re- 
 lieved through eye treatment, because it was a 
 symptom of an eye condition, not of gout, or kidney 
 trouble ; yet it would be absurd to claim that the 
 general disease had yielded to cylinders, prisms, or 
 operations upon the eye muscles. In patients with 
 digestive disturbances, dizziness and nausea are more 
 apt to occur from muscular asthenopia than in other 
 cases, and these sensations no doubt occur frequently 
 from other causes; yet so many of these cases are 
 more or less benefited by eye treatment that, as 
 before mentioned, the symptoms should excite sus- 
 picion of eye strain. Cases are seen by the eye
 
 24 Heterophorias and Insufficiencies. 
 
 specialist in which eye treatment has been unduly 
 delayed while general treatment was kept up for eye 
 symptoms; he has no good opportunity to know 
 the other side of the question. 
 
 The general rule of double causation must be ap- 
 plied in these cases; there are cases of eye devia- 
 tions of the same character as those which cause 
 trouble, which with just as hard use of the eyes 
 cause no asthenopic symptoms whatever; hence 
 these symptoms must be referred, when they occur 
 from eye errors, to such errors working upon some 
 general condition susceptible to these symptoms. 
 
 In the cases of choreic blepharospasm, or spasm 
 of the facial muscles, occurring with or without other 
 choreic symptoms, we are often able to obtain relief 
 by treatment of heterophoria, refractive error, or 
 inflammatory lesion of the eye or appendages, yet 
 in an active stage of general chorea it has seemed 
 to me that treatment of the ocular muscles some- 
 times did more harm than good ; prisms cannot be 
 kept straight in front of the eyes, the conditions 
 of the muscles are so variable that it is hard to tell 
 the nature of the original tendency, and muscle 
 operations are likely to increase general nervous 
 irritability. 
 
 Dizziness may go on to vertigo in certain cases of 
 eye strain. Dizziness and giddiness are used prop- 
 erly as synonymous terms, while by vertigo is meant
 
 A Clinical Study. 25 
 
 temporary loss of consciousness. Vertigo in this 
 sense is not of frequent occurrence from hetero- 
 phoria, yet in occasional instances may take the 
 form of fainting spells accompanied by falling. 
 This is the only kind of epilepsy I have personally 
 known to be relieved by eye treatment. 
 
 When a patient who is in the habit of reading 
 himself to sleep gets eye strain and cannot sleep be- 
 cause he cannot read with comfort, correction of his 
 eyes may cure his insomnia; yet eye treatment as a 
 cure for insomnia has usually failed in my hands. 
 
 I have seen cases of nervous unrest accompanying 
 hyperphoria or esophoria in which the patient said 
 she felt like throwing herself out of the window, and 
 met with one case in which there was ground to be- 
 lieve that the muscular deviation had actually helped 
 to cause a temporary suicidal mania. 
 
 Statements on record to the effect that severe 
 general headache, spinal irritation, dizziness and 
 nausea are common symptoms of refractive error, 
 because they disappear with correction of the refrac- 
 tion, are to be received with caution; a careful con- 
 sideration of this matter convinces me that these 
 symptoms are in such cases usually due to hetero- 
 phoria which is incidentally relieved by correction 
 of the refraction, as in accommodative esophoria. 
 
 Although the muscular deviations accompany- 
 ing errors of refraction will receive our first
 
 26 Heterophorias and Insufficiencies. 
 
 consideration, the symptoms will not be described 
 from this class so much as from those cases in which 
 the refractive error played no part, even if it existed. 
 
 It is well to remember that a headache which 
 wakes a patient from sleep is not likely to be due to 
 the eyes, and if it markedly decreases or disappears 
 after the patient has been up and about for a time 
 the eyes may be eliminated as a causative factor, 
 except in a few cases where there is an eye error for 
 near work which does not cause strain for distant 
 vision ; these latter cases are free from headache 
 when they do no near work, but after hard use of 
 the eyes in the evening may wake with a headache 
 the next morning, which passes off later in the day. 
 
 It seems to be accepted as a matter of course that 
 the asthenopia due to muscular deviations will cease 
 if one eye only is used. The closing of one eye 
 long enough for diagnostic purposes in the usual 
 class of patients who suffer from asthenopia, with 
 their weak nerves and strong desire for binocular 
 fixation, is fraught with difficulty, and this principle 
 finds its application mostly in the treatment of aniso- 
 metropia. There may be an occasional case in which 
 it is advisable to shut off one eye with a piece of 
 ground glass in a spectacle frame for the diagnosis or 
 relief of asthenopia, and personally I prefer this 
 method to the removal of an eye which must neces- 
 sarily be possessed of useful vision, a feat which I
 
 A Clinical Study. 27 
 
 am forced to believe by reliable authority has been 
 performed for the relief of symptoms supposed to 
 be due to heterophoria. 
 
 Of course the symptoms of muscular asthenopia 
 depend upon binocular vision, and the man who ex- 
 pects to cure strain in one eye by tiring them both 
 would hardly be expected to meet with success ; yet 
 I frequently find a patient with a plane or nearly 
 plane glass over one eye and a strong lens over the 
 other, who announces that the oculist who gave these 
 glasses found that one eye was doing all the work, 
 and corrected the other with a glass so that it might 
 relieve the strain from which the first one was suffer- 
 ing. Many men have gone through the phase of 
 full correction of each eye, as their seniors did not 
 properly warn them, not caring to dwell upon that 
 time when they too had discovered the secret of the 
 cure of all asthenopia with good vision in either eye. 
 A patient with anisometropia with much difference 
 between the refraction of the eyes will bear full cor- 
 rection of the two eyes just so long as he does not 
 use them together. There are many other diffi- 
 culties of fusion in such a case in addition to the 
 esophoria in one lateral direction, the exophoria in 
 the opposite one, the hyperphoria on one side upon 
 looking down, on the other when looking up, from 
 the prismatic action of one lens in excess of the 
 other; even if the patient looks through the centre
 
 28 Heterophorias and Insufficiencies. 
 
 of the lens, or the English proposition is carried out 
 to have the strength of the lenses similar at the 
 periphery with a central paster to correct the eye 
 with greater error, the unequal antero-posterior 
 shifting of the nodal points, with other reasons for 
 dissimilar retinal images, will still obtain. 
 
 To my mind the most satisfactory combination 
 of eyes for a life's work would be to have one em- 
 metropic, the other myopic about 3 D's. In cases of 
 anisometropia in which the difference corresponds 
 to this, yet astigmatism is present, it is well to 
 consider the astigmatism alone ; in myopia with a 
 difference of 2. or 3. between the eyes it is well to 
 have a pair of glasses in which the eye with less 
 myopia is fully corrected by a glass and the other 
 lens matches this or nearly so. I carry this idea 
 so far as to occasionally correct in hypermetropic 
 and presbyopic cases the eye with the greater error 
 for distance, and with a glass which equals this in 
 strength, as nearly as the case will allow, the pres- 
 byopia of the other as well. It is absolutely nec- 
 essary to determine that the first eye does not 
 strain its accommodation in order to read with the 
 other, and render such correction impracticable. 
 
 The scope of this treatise will not allow a full dis- 
 cussion of this class of cases, in which any man is 
 liable to meet with disaster, further than to give a 
 few additional points regarding correction. The
 
 A Clinical Study. 29 
 
 deviation of the eye with poorer vision (fortunately 
 the one with greater error in most instances) is deter- 
 mined by certain conditions in the better eye as 
 well as its own weaknesses. Note in this connec- 
 tion the effect upon the defective eye of correcting 
 glasses upon the better eye in squint cases. It is a 
 matter of great importance to find out in such cases 
 just how strong is the impulse to binocular fixation 
 and the ability to ignore or suppress the image of 
 one eye; if the muscular condition is bad and the 
 tendency to binocular fixation can be strengthened, 
 it is justifiable to cultivate the latter in the interests 
 of vision, although muscular asthenopia may result 
 which demands treatment. 
 
 The difference in strength between two glasses to 
 which the eyes may accustom themselves depends 
 upon the age and character of the patient and the con- 
 dition of the ocular muscles, with some other factors 
 which cannot be determined clinically at present. 
 With one exception, cylinders with considerable 
 amount of difference are borne better than spheres 
 with like differences because there is no prismatic 
 effect in the direction of the axis ; differences between 
 cylinders with the axes vertical are better borne than 
 in those with the axes horizontal. Patients with 
 strong muscular action, especially in the direction 
 of difference (for instance, strong sursumduction 
 with horizontal cylinders) bear differences better than
 
 30 Heterophorias and Insufficiencies. 
 
 those with weak muscular action ; this is partly local, 
 partly because the latter condition accompanies neu- 
 rasthenia. Sursumduction of i. is weak, 2. ordinary, 
 2.50 and above strong. People who turn the head 
 and look through the centres of their glasses bear 
 glasses better than those who look at objects through 
 or beyond the edges. Difference of glasses of 2. may 
 be well borne by young people (under twenty years 
 of age), while I. may be the limit past middle life. 
 The best borne differences are in cylinders with verti- 
 cal axes as before mentioned, and the worst are a 
 vertical cylinder over one eye, horizontal over the 
 other, in this case concave cylinders being worse 
 borne than the convex; in myopic astigmatism cyl- 
 inder .5 in each eye, one vertical, the other horizon- 
 tal, is usually not a complete success. 
 
 Let me repeat for the benefit of those who have 
 had no trouble so far in giving glasses with great 
 differences, that almost invariably the patient in 
 such cases suppresses the image of one eye, or at 
 least does not have binocular vision. The only 
 cases in which such a correction is really indicated 
 occur among patients with no tendency to asthenopia 
 where it is desirable to better the field on the side 
 of the defective eye.
 
 CHAPTER II. 
 
 HYPERPHORIA. 
 
 THE symptoms of hyperphoria differ from those 
 of other forms of heterophoria mostly in de- 
 gree. The headache is below the occiput, or may 
 be general and accompanied by dizziness and nausea ; 
 it is pretty constant, although varying in intensity, 
 in many cases perhaps passing away during a night's 
 rest and increasing toward evening, unless the pa- 
 tient rests with the eyes shut during the day; 
 occasionally in hyperphoria cases supra-orbital or 
 ciliary pain on one side is present, but it is doubtful 
 whether this can be due to the muscular deviation 
 alone. In this form of heterophoria congestion of 
 the eyeball accompanying low grade conjunctivitis 
 is more apt to occur than in other forms, and it is 
 more likely to be present in those cases occurring 
 with oblique astigmatism ; the conjunctival trouble 
 is made worse by caustics and astringents, and is 
 often in literature grouped with cases described as 
 gouty lids, or in some instances among cases of 
 spring catarrh as an atypical type in which the 
 
 31
 
 32 Heterophorias and Insufficiencies. 
 
 anatomical signs of true Saemisch's catarrh are 
 absent. 
 
 The marginal blepharitis which occurs in some 
 cases of increased lacrimal secretion is due to 
 irritation from the discharge, which runs over the 
 edges of the lids by day, when they are open, and 
 also at night because there is a predisposing ana- 
 tomical condition in blepharitis cases, consisting 
 of a shortness of the vertical measure of the lids, 
 compared to the horizontal length, which prevents 
 proper closure at night. This fact, which has been 
 strangely overlooked by recent writers on lid in- 
 flammations, was fully proven by Fuchs and can be 
 verified clinically with great ease ; the lower edge 
 of the cornea even may be exposed at night, and 
 ulcerations in this situation may sometimes be rap- 
 idly cured by a night bandage, while resisting other 
 treatment. It is by consideration of the shortened 
 lids that we understand why relapses occur when 
 ointments are no longer applied in cases of blephari- 
 tis marginalis, and why correction of the refraction 
 or a muscular defect may sometimes permanently 
 improve the condition by decreasing conjunctival 
 congestion and lacrimation. 
 
 In hyperphoria hyperesthesia retinae and some 
 nervous irritability are apt to be present. A sign 
 which should always excite suspicion of hyper- 
 phoria is a tipping of the head toward the shoulder.
 
 A Clinical Study. 33 
 
 The head is tipped downwards toward the right 
 shoulder in most cases of left hyperphoria and some 
 of right hyperphoria; in other cases of the latter 
 anomaly it is tipped toward the left shoulder. The 
 cause of this tipping is not entirely clear; on first 
 thought it would seem as if it might occur in order 
 to bring the eye with the higher image more nearly 
 on a level with the other, but this fails to explain 
 all cases. It should be remembered that men are 
 in the habit of tipping the head toward the right 
 shoulder in aiming rifles, and also in sighting lines 
 and objects in many occupations ; the right shoulder 
 is lower than the left in right-handed people, and I 
 believe that the sterno-mastoid and other muscles on 
 the right side of the neck and head are also more 
 powerful. May not the position of eyes and head 
 be sometimes due to a common cause ? 
 
 The right ear is usually lower than the left and 
 consequently spectacles sag downward on this side ; 
 eye-glasses having chains attached to the right lens 
 also sag in the same direction. That vertically de- 
 centred lenses are a common cause of hyperphoria 
 I have little doubt, having known it to occur from 
 a misplaced glass, in cases where there had been 
 orthophoria, and disappear after the glass had been 
 straightened and worn correctly for a time; on the 
 other hand there is a connection in some cases be 
 tween the position of the glass and the hyperphoria
 
 34 Heterophorias and Insufficiencies. 
 
 which is due to a displacement by the patient in or- 
 der to correct the deviation and obtain comfort. I ex- 
 amined at one time glasses made by leading opticians 
 and found about one half with the optical centre of 
 one glass above that of the other; there is very 
 much variation in the number of these errors be- 
 tween different manufacturers; glasses of a pair 
 made at different times, as when a broken glass is 
 replaced, are more apt to be incorrect in this way. 
 
 Another certain cause of hyperphoria is muscular 
 anomaly, which may be a paresis or an excess. 
 Take a recent case in which I found right hyperphoria 
 of 5. manifest, 2. latent; right sursumduction 10., 
 left sursumduction 2. ; myopic astigmatism .5 
 right eye, .25 left ; axis of glass 135 and 60 
 respectively. The left eye seemed to lag behind 
 in upward movement of the eyes, and there was 
 diplopia in the left upper quadrant of the field ; in- 
 sistent questioning regarding diplopia brought out 
 the statement that the patient thought that she 
 remembered seeing double about three years ago. 
 This appears to be a case of paresis of the left 
 superior rectus, though why a healthy woman of 
 forty-six years should have developed paresis of an 
 isolated muscle is a mystery. Investigations upon 
 injuries to the eyes during childbirth may throw light 
 upon the etiology of this class of cases as it is now 
 doing with congenital amblyopia. Another test of
 
 A Clinical Study. 35 
 
 the muscles of a woman of fifty-six years with 0.75 
 D's of hypermetropic astigmatism against the rule in 
 one eye, 1.50 in the other, and orthophoria, showed 
 that divergence varied from 10. to 14., convergence 
 from 13. to 1 6., right sursumduction was 4., left 
 sursumduction n. This seemed to be a case of 
 excess of the left superior rectus. 
 
 Assuming it to be evident that low degrees of 
 hyperphoria may be due to misplaced glasses and 
 high ones to muscular defect, I think I may add 
 one more positive cause for its production. I 
 have found a number of cases with the right eye 
 functionally or optically stronger than the left, in 
 which left hyperphoria first appeared only upon 
 convergence, then became manifest with fixation 
 lines laterally parallel. This I believe to have been 
 due to the fact that the right eye not only con- 
 verged more strongly than the left, but also that the 
 depressor muscles of the cornea were stronger; that 
 it tended to go below the left first upon convergence, 
 then permanently; I am sure this is the mechanism 
 in some cases of convergent squint with sursum- 
 vergens, and although the squinting eye deviates 
 upward it is really because the other went below it 
 in the first instance. 
 
 The other causes now to be given to account for 
 hyperphoria I consider rather speculative. The first 
 is that when eyes are on a different level the muscles
 
 36 Hcterophorias and Insufficiencies. 
 
 become abnormal by attempting to bring the visual 
 lines on a horizontal plane; this may be an occa- 
 sional cause, as the two conditions coexist; yet if 
 there is orthophoria, hyperphoria is not caused by 
 tipping the head, in the few cases that I have studied 
 in order to note the effect of difference in level of 
 the eyes upon the ocular muscles, which brings us 
 to the connection between hyperphoria and wry neck. 
 In hyperphoria the head is inclined to the side 
 with a twist, the base line (between the centres of 
 rotation) sharing in the inclination ; in the limited 
 observations of spasmodic wry neck I have made, 
 there was a more or less successful attempt to adjust 
 the eyes (having no hyperphoria) by bringing them 
 up on a horizontal line by giving a compensatory 
 twist of the head away from that of the neck. 
 
 The head tipping in hyperphoria causes lateral 
 curvature of the spine; the mechanism is perfectly 
 apparent ; I have seen such cases, and I think they 
 occur somewhat frequently. The present methods 
 of keeping a child's head straight in school work, 
 and the introduction of vertical script do not meet 
 the conditions in hyperphoria any more than in cer- 
 tain cases of astigmatism, and may in some instances 
 result in the very troubles they are intended to 
 prevent. 
 
 The next speculative consideration in the produc- 
 tion of hyperphoria is optical. That anomalies of
 
 A Clinical Study. 37 
 
 the elevator and depressor muscles of the eyes may 
 change the axis of astigmatism by a rotary action of 
 the cornea in some instances may be true, but that 
 does not account for the production of the hyper- 
 phoria. I have looked over one thousand cases 
 tested for refractive and muscular errors in the last 
 three years and find 465 (46.5 %) with oblique astig- 
 matism ; all other refractive errors 535 (53.5 $). By 
 oblique astigmatism I mean with the axis not ex- 
 actly vertical or horizontal, and the above proportion 
 is about what I have found in my cases for many 
 years. If the cylinder gives no better vision at an 
 oblique axis than when straight, or than a spherical, 
 the case is not counted as oblique astigmatism. 
 Hyperphoria occurred in 20.8% of all cases; in the 
 oblique astigmatic cases 26.6$, in the others 14$. 
 Hence there is evidently a connection between an 
 oblique axis of astigmatism and the production of 
 hyperphoria. There were nearly double the number 
 of hyperphorias in women that there were in men, 
 but as the proportion of women to men was not 
 much less than that, the percentage may be con- 
 sidered nearly equal. In women right hyperphoria 
 occurred in general more often than left by about 
 20%. In oblique astigmatism it was rather more fre- 
 quent by comparison than in other cases. In men 
 left hyperphoria was more than twice as frequent as 
 right, in refractive errors other than oblique astig-
 
 38 Heterophorias and Insufficiencies. 
 
 matism the proportion being more than 2.5 to i. 
 The explanation of the more frequent occurrence of 
 left hyperphoria in men has been already touched 
 upon. Men are more right eyed because of their 
 habits and training than women (about half of whom 
 are so binocular that they cannot wink), and have 
 more tendency to depress the right eye. If men 
 and women with better vision in the left eye, and 
 women with equal vision in the two eyes are elimi- 
 nated, the proportion of left hyperphoria to right 
 perceptibly rises; this is even more apparent if left- 
 handed persons, who use the left eye in shooting, 
 are also left out of the count. It is perfectly evi- 
 dent from a study of these cases of hyperphoria, 
 leaving out the purely muscular cases, which may or 
 may not cause torsion of the vertical meridian, that 
 there is a class of cases caused by oblique astig- 
 matism. There are three ways in which this may 
 be explained; first by inco-ordination of muscular 
 action ; second, by an attempt on the part of the 
 rotating muscles to change the axis to a better po- 
 sition; this latter explanation seems plausible until 
 it is applied to the cases singly, when it is seen to 
 be inapplicable to many. Some of these hyper- 
 phorias disappear with the proper correcting glasses, 
 and the disappearance is not always due to pris- 
 matic action, although this is hard to eliminate; 
 a third way to explain the combination we are
 
 A Clinical Study. 39 
 
 considering is to suppose that in some of these cases 
 the muscles are normal, but the vertical deflection of 
 light caused by difference in the height of the 
 corneal centres gives the vertical displacement 
 shown by the test, which is optical, not muscular. 
 This idea has a practical side, which is that oblique 
 cylinders can be sometimes adjusted so as to cause 
 hyperphoria to disappear, and that accuracy in find- 
 ing exactly the proper axis of a correcting cylinder 
 is an important consideration. 
 
 Latent muscular trouble is like latent hyperme- 
 tropia. It is that portion of the ocular error which 
 the observer fails to find ; what is latent at one time 
 to one man is manifest to another under other con- 
 ditions. When the amount of hyperphoria equals 
 the difference between right and left sursumduction 
 it is usually all manifest ; when hyperphoria is less 
 than this difference, there is probably some of it 
 latent, which is likely to become manifest later. 
 This sounds correct, and has proven so to my mind, 
 but it presupposes a diagnosis of hyperphoria, which 
 is not always easy to make. It is my purpose to 
 present as nearly as possible a composite picture 
 of the more frequent and ordinary weaknesses of 
 muscular action, since neither the writer nor reader 
 could stand a detailed statistical description of some 
 thousand cases ; an occasional history to emphasize 
 the rule by showing the exception, or to illustrate
 
 4O Heterophorias and Insufficiencies. 
 
 the occurrence of what is frequently denied to exist, 
 seems to be indicated. I used to share in the sneers 
 of my medical friends regarding latent hyperphoria 
 even after being convinced of the frequency and im- 
 portance of the trouble itself. In June, 1892, a boy 
 of thirteen years who had been under the care of a 
 careful and competent ophthalmologist and fitted by 
 him two years before with sph. .5 O c yl- -5 
 changed to me as a matter of convenience. Under 
 atropine I found myopia of 2.50 with myopic astig- 
 matism of i. in addition, vision = f$; there was or- 
 thophoria with prism convergence at 20 feet of 16., 
 divergence 7. A diagnosis of slowly progressing my- 
 opia with congestion of the choroidal and conjuncti- 
 val vessels was made and some asthenopia which was 
 present seemed natural under the circumstances. 
 Although the myopia and astigmatism increased 
 only about 1.50 in the next two years, still the cho- 
 roidal condition in connection with it was held to 
 fully account for the increasing hyperesthesia of 
 the retina, and with changes in the nasal mucous 
 membrane for the lacrimation and recurrent attacks 
 of follicular conjunctivitis, which latter came on 
 several times in the two years and were apparently 
 successfully combated with astringents, although 
 treatment of the nose was instituted during one 
 attack before it began to yield. Vision by this time 
 hovered about f$, being usually rather below this,
 
 A Clinical Study. 41 
 
 and the headaches and eye weakness had increased 
 so that the boy was kept out of school and not per- 
 mitted to go into business. Twenty-seven months 
 after I first saw him he came into my office suffering 
 from an exacerbation of his trouble, which was by 
 now pretty constant as regarded lacrimation and 
 severe headache, and as he attempted to look at me 
 with his congested eyeballs some sort of a chemical 
 change occurred in my memory cells which insisted 
 to me that there must be hyperphoria here. A test 
 with the Maddox rod showed i^ (old style) of right 
 hyperphoria, which is usually more potent for mis- 
 chief than left hyperphoria. A little coaxing 
 brought out 2 the next day, and prisms of .75 were 
 ordered in each eye, base down right eye, base up 
 left, with the sphere-cylinders as before. The re- 
 sult was cessation of headache and decreased 
 conjunctival congestion and lacrimation almost im- 
 mediately ; the patient read f $ -f- with either eye 
 one week later and went into business; had one 
 headache in a year, but found that he had fever at 
 the same time and went to his family doctor. In 
 eighteen months all elements in the glass were 
 slightly increased in strength, the prism now being 
 i. o. u. Two and a half years after this, Septem- 
 ber, 1898, the eyes began to be uncomfortable again, 
 and examination showed V. = f$ with sphero-cylin- 
 ders slightly increased in strength, right hyperphoria
 
 42 Heterophorias and Insufficiencies. 
 
 3.50. In the glass ordered prisms were increased to 
 1.50 each and the patient told that should his head- 
 ache return after a time an operation would be indi- 
 cated, as stronger prisms would not do as well as the 
 others. I have heard of the patient once lately 
 and he was reported comfortable. This is a case of 
 hyperphoria which had been latent to me; to some 
 men all hyperphoria is latent. 
 
 There is some interest taken in the usual course 
 of hyperphoria ; it shares with some other things a 
 tendency to appear or disappear, increase or de- 
 crease or remain stationary. It usually increases, 
 and I doubt whether the high amounts ever disap- 
 pear without operation, unless they are caused by 
 transient paresis of an ocular muscle. 
 
 Hyperphoria of .25 should, I think, be ignored, 
 and I wish I could say the same of hyperphoria of 
 .50, but this causes occasionally some trouble, de- 
 pending upon the sensitiveness of the patient and 
 weakness of sursumduction ; thus, if sursumduction 
 shows respectively I. and 1.50, a deviation of .50 is 
 apt to cause discomfort. Larger amounts are potent 
 sources of mischief until among the higher grades 
 some of them become strabismus sursumvergens and 
 muscular asthenopia becomes improbable. It is well 
 to correct the manifest hyperphoria entirely with 
 prisms, or only leave .25 or .50 uncorrected, up to an 
 amount of 2 Ds. From 2.50 to 3.50 or above from
 
 A Clinical Study. 43 
 
 three fourths down to two thirds may be corrected. 
 In hyperphoria of 3. and upwards it is better in gene- 
 ral to operate, but it is often convenient to try prisms 
 in order to note the effect and convince the patient 
 of the necessity for operation when more hyper- 
 phoria becomes manifest, as it is likely to do in a 
 year, more or less. If manifest hyperphoria of i. 
 or less is to be corrected, I order the prism over the 
 eye with poorer vision, and in cases with equal 
 vision over the left. This leaves a chance to change 
 only one glass when increased prismatic correction 
 is indicated at a later time. Correction of 1.50 or 
 over it is well to distribute between the eyes, base 
 down over one, base up over the other, unless the 
 deviation is decidedly limited to one eye. Other 
 indications for varying the position of the prisms 
 are limitation of upward or downward movements, 
 use to be made of the glass, and other minor 
 considerations. Take for instance the common 
 condition of left hyperphoria with I. of hyperphoria 
 with the rod over the right eye, 1.5 when it is over 
 the left eye. In this case the right eye is more used 
 to fixing, and were it a case of squint the left eye 
 would deviate. A prism of I. base up right eye in 
 such a case would be likely to cause more difficulty 
 when first worn than one of 1.50 base down left eye, 
 for obvious reasons. 
 
 It is easy to demonstrate the necessity of vertical
 
 44 Heterophorias and Insufficiencies. 
 
 prisms in many cases; if the prism correcting the 
 hyperphoria is placed over one of the glasses correct- 
 ing the refraction, then reversed, most patients can 
 tell which direction is comfortable and which dis- 
 tressing without any hypnotic suggestion. 
 
 It is usually presupposed that there is an error of 
 refraction to correct in considering the ordering of 
 prisms. If no correcting glasses are needed it would 
 be better to operate in suitable cases, as many pa- 
 tients cannot be depended upon to wear glasses 
 which do not help vision, even when symptoms are 
 relieved by them. I have seen simple vertical 
 prisms dropped in a case of hyperphoria because the 
 headache was better; two years later the child af- 
 fected was under treatment for lateral curvature of 
 the spine. The headache returned after a time but 
 the glasses seemed if anything to make it worse; 
 inquiry showed that one prism had dropped out of 
 the frame and been replaced with the base in the 
 same direction as the one on the other side. This 
 sort of thing is of frequent occurrence and produces 
 curious consequences. A patient of mine aged 
 eighty -two had hyperphoria of 3.50 and had suffered 
 all her life from severe and frequent attacks of head- 
 ache, with nausea and vertigo; measures for her 
 relief had proved futile, the condition being de- 
 scribed as " very bad for the last thirty years." I 
 introduced prisms into the corrections for hyper-
 
 A Clinical Study. 45 
 
 metropia and presbyopia (+2.75 and +5., with 
 which latter glass Jaeger No. I could be read up to 
 8"), which were about the same as were then being 
 worn. Two months later the old lady reported with 
 great delight that her headaches were relieved. 
 Three years later this patient returned with evident 
 senile hebetude, and upon being asked about the 
 headache said that the relief had been only tempo- 
 rary ; it turned out that she had dropped the glasses 
 for distance, and when told that such a course had 
 caused the return of the trouble, was very positive 
 that she did not need any distant glasses, as she 
 could see well enough without them. Spherical 
 -f-6. was ordered for near work, with prisms, and 
 energetic orders given that the distant glasses should 
 be worn. This energy was not thrown away, for 
 eighteen months later the patient again appeared 
 with glasses on and said that her eyes were trouble- 
 some still; the young lady who now accompanied 
 her corroborated this by saying, " Yes, grandma's 
 eyes are uncomfortable, and she does not see well 
 either." The old lady was wearing constantly the 
 -{-5. formerly given for near work. 
 
 Prisms are very successful in relieving asthenopia 
 and headache when properly applied in hyperphoria 
 cases, yet sometimes fail when the vertical trouble 
 is secondary to a lateral deviation, or when with 
 vertical and lateral deviations the latter is causing
 
 46 Heterophorias and Insufficiencies. 
 
 the symptoms. Some ophthalmologists ignore hy- 
 perphoria altogether in corrections, while others al- 
 ways correct or operate upon it first, knowing the 
 dire consequences which sometimes follow the oppo- 
 site course. It is safer to correct the hyperphoria 
 first in doubtful cases, and watch the effect upon the 
 lateral muscles ; if the vertical deviation is small in 
 amount proportionately to the lateral and only occurs 
 with esophoria or exophoria as the case may be, and 
 not in the centre of the field, it may safely be set 
 down as secondary. In a case of hyperphoria of 
 this type with severe and constant headache, which 
 had remained after careful correction of the refrac- 
 tion under atropine and trial of various vertical 
 prisms during a year, I took out the prisms, gave 
 the less hypermetropic correction without atropine 
 at a first examination, as there was exophoria, and 
 the headache quickly subsided unless near work was 
 done, then after a time entirely. My colleague of 
 a neighboring city, who had been so carefully study- 
 ing and treating the case before he came very prop- 
 erly to the question of operation, would be a little 
 surprised, perhaps, if he knew how easily relief was 
 obtained. 
 
 In considering the relative importance of the ver- 
 tical and lateral deviations it may sometimes be ad- 
 visable to order an oblique prism. I have this day 
 seen a patient who was wearing a prism base out
 
 A Clinical Study. 47 
 
 over one eye, base up over the other. An easy way 
 to figure an oblique prism is to take some unit of 
 measure (as a centimetre) and draw a vertical line 
 with the same number of units as the number which 
 marks the strength of the prism desired to correct 
 the hyperphoria. At the end of this line another 
 at right angles is drawn with the number of units 
 corresponding to the horizontal prism desired, then a 
 parallelogram constructed. Keeping the direction 
 of the prisms in mind, a diagonal line is now drawn 
 from the corner where the apices would meet to that 
 between the bases, which in the units of measure 
 will show the strength of the oblique prism, and by 
 its direction the axis. This oblique prism is the 
 exact equivalent of the combination of the two 
 others. 
 
 In operating for hyperphoria, tenotomy of the 
 stronger superior rectus is usually done, for what 
 seem to the writers upon the subject good and suffi- 
 cient reasons. I have not as yet had to advance an 
 inferior rectus except in cases of strabismus. In 
 order to do the operation the eye is rendered super- 
 ficially insensible to pain by cocaine or holocaine. 
 I use the latter because it penetrates more deeply 
 and has no effect on the circulation and pupil. 
 There is apparently less secondary subconjunctival 
 hemorrhage and oedema than from cocaine, but I 
 have seen many more attacks of faintness following
 
 48 Heterophorias and Insufficiencies. 
 
 its use than I ever saw after cocaine, so I incline to 
 think it more toxic and have whiskey close by when 
 I use it. After the eye is flushed with neutral salt 
 solution the upper lid is supported by the ring finger 
 of the left hand, which holds a pair of fine-pointed 
 forceps between the forefinger and thumb. The little 
 finger is understudy for the ring finger, the middle 
 finger goes with the forefinger. As the eyeball is 
 directed downwards the conjunctiva is grasped over 
 the middle of the insertion of the superior rectus 
 muscle, and with the tenotomy scissors in the right 
 hand a cut is made. Through this the centre of the 
 muscle tendon is grasped by the forceps and cut ; 
 from this laterally cuts are made, with the tendon 
 grasped between the blades of the scissors, until 
 orthophoria is obtained, the eyes being tested after 
 each cut. A bandage should be worn, for comfort 
 and to control hemorrhage, but a few hours; if the 
 patient then uses the eyes the full effect of the 
 operation may remain, or may be kept by forcing 
 downward motion. The deviation may partly re- 
 turn, one third of the original being the most I have 
 as yet seen come back, but allowance cannot be 
 made for this without risk of over-correction. In 
 this tenotomy there is usually a scarlet-looking eye 
 by the second day, as the blood under the conjunc- 
 tiva settles downwards on both sides over the sclera ; 
 the main trouble I have experienced from this
 
 A Clinical Study. 49 
 
 operation has been annoyance from the complaints 
 concerning the red eye from patients and their 
 friends. The fine-bladed scissors of Stevens I have 
 had to give up after trials of several pairs; they 
 tangle up in the muscle fibres and do not cut cleanly 
 through them when the muscle is well developed, 
 and considerable effect is desired, as in most cases 
 upon which I operate.
 
 CHAPTER III. 
 
 ESOPHORIA. 
 
 DESCRIPTIONS of that type ot headache 
 called migraine all need to be remodelled 
 from the standpoint of recent knowledge of eye 
 strain, and especially with reference to the type of 
 headache occurring from esophoria. The only 
 headaches of the " sick headache " type which are 
 extremely unlikely to occur from esophoria are those 
 in which gastric or intestinal disturbances of a marked 
 type precede the headache, and this occurs in the 
 form of very severe hemicrania ; in this type of head- 
 ache there is sometimes a suspicion of some station- 
 ary and chronic change in the bones of the skull, 
 causing pressure or irritation of the brain, its mem- 
 branes, or its blood-vessels, in which case paresis of 
 an external rectus muscle may occur with the head- 
 ache attacks. Possibly spasm of convergence may 
 occur from irritation of the convergence centre in 
 migraine cases, but it is rare. A good illustration 
 of a form of sick headache not due to ocular anomaly 
 may be found in cases of arterio-sclerosis ; these 
 
 50
 
 A Clinical Study. 5 1 
 
 latter headaches increase with age and are to be 
 differentiated not so much from the headaches of 
 esophoria as from those of exophoria. 
 
 The regular history of the headache of esophoria, 
 which is uncomplicated by other forms of eye error, 
 is that it is periodic, and accompanied by dizziness 
 and nausea. Its occurrence may be usually traced 
 to prolonged use of the eyes in distant vision ; thus 
 it occurs after attendance at a theatre and is apt to 
 be referred to the close air ; after shooting at a rifle 
 range, when it is supposed to be due to exposure to 
 draughts of fresh air; after a course of art study or 
 the like, when it is known to come from lack of exer- 
 cise ; after bicycle rides, when it is considered evident 
 that it is due to too much exercise. During or 
 preceding the attacks the latent esophoria is apt to 
 become manifest, and in some cases, whether mus- 
 cular or accommodative, homonymous diplopia may 
 result. In most cases of headache from esophoria 
 the trouble tends to diminish toward middle age as 
 the interni become weaker and the refractive error 
 becomes manifest ; and this result is referred to all 
 sorts of causes except the real one, which is spon- 
 taneous improvement or disappearance of the 
 esophoria. 
 
 It must be kept in mind in all cases of heterophoria 
 that there may be no symptoms at all (in which case 
 the deviation requires no treatment,) or all of the
 
 5 2 Heterophorias and Insufficiencies. 
 
 usual symptoms, or any combination of them. It 
 has happened to me to observe much dizziness, with 
 or without nausea, from esophoria, and more cases 
 of vertigo in this than other heterophorias; in fact 
 this and hyperphoria have so far furnished the few 
 cases of vertigo with falling that I have seen relieved 
 by eye treatment. 
 
 Accommodative Esophoria. Esophoria with Hy- 
 permetropia. Esophoria is usually accommodative 
 and due to spasm of convergence, accompanying 
 spasm of accommodation, in uncorrected hyper- 
 metropia. When i. or less it may be ignored ex- 
 cept in cases of neurasthenic muscular asthenopia 
 with weak action of the interni and externi ; in rare 
 cases esophoria of i. or less may be due to false pro- 
 jection, the eyes converging for 20 feet and the 
 mind projecting the images to infinity. In many 
 cases of accommodative esophoria in young people 
 the case may be diagnosed with ease. Divergence 
 is not below normal, and when a proper correction 
 for hypermetropia is put upon the eyes orthophoria 
 or even exophoria and excess of divergence may im- 
 mediately result, or develop after the glass correction 
 has been worn for some time. 
 
 In view of the peculiar expression some ophthal- 
 mologists have at the mention of esophoria with in- 
 sufficiency of the interni or excess of the externi, 
 as well as the peculiar statements in some quarters
 
 A Clinical Study. 53 
 
 about the lack of effect upon convergence through 
 the accommodation, let me present the case of a lad 
 who came into my office a few days ago and saved 
 me the trouble of deciding which of the many cases 
 among the histories of such should be described, as 
 I do not expect any other to present a more marked 
 example of divergence excess and esophoria. The 
 boy's age is sixteen, and +2.75 spherical is being 
 worn. There is -|~4-5O of hypermetropia, and .50 
 of astigmatism in addition, with better accommoda- 
 tion in the right eye than the left. V. = f$, R. E., 
 f$, L. E. At 20 feet there is an esophoria of 4.5, 
 convergence 20., with forcing after instruction and 
 practice 35., a little left hyperphoria with conver- 
 gence. Divergence 15. The convergence near point 
 is 5 inches, at which distance the eyes begin to 
 diverge, although by an effort fixation can be recov- 
 ered and the eyes forced to converge nearer. Exo- 
 phoria at 13", 4 D's. With full correction of the 
 refraction there is orthophoria, divergence still 15., 
 convergence not so good as without the glass. If I 
 may judge by experience these eyes will have exo- 
 phoria before long, and perhaps divergent squint 
 later, although without proper correction of the re- 
 fraction there is now periodic convergent squint 
 which the patient has observed. These cases should 
 be treated for the accommodative esophoria first by 
 correcting the refraction, later for the exophoria and
 
 54 Heterophorias and Insufficiencies. 
 
 excess of the extern! by tenotomy of the latter 
 muscles; always provided there is muscular asthe- 
 nopia or the condition is passing into strabismus. 
 
 The diagnosis of accommodative esophoria is not 
 always easy. As time goes on in these cases, if the 
 refraction is not corrected, divergence becomes 
 weaker and may be as little as 5., seldom lower. It 
 may well be asked why divergence of less than 5. 
 should be arbitrarily given as not belonging to ac- 
 commodative esophoria when it is well known that 
 convergent squint is often if not usually of accom- 
 modative origin. It seems to me that in cases 
 where the desire for binocular fixation is so strong 
 that it will allow esophoria only to result, and where 
 the spasm of accommodation and convergence ex- 
 cept for this desire would cause squint, the externi 
 would hardly fall below a standard of power suffi- 
 cient to insure binocular fixation, with a margin left 
 for emergencies, unless they were insufficient ; for 
 practical purposes, divergence of 4. or less should be 
 considered as a muscular insufficiency, unless conver- 
 gence is also correspondingly weak, when the case 
 belongs to another class to be considered later. 
 
 All cases of esophoria with headache, dizziness, or 
 nausea after use of the eyes for distant vision, in 
 which the muscular deviation does not yield to cor- 
 rection of the manifest hypermetropia, should (un- 
 less surely myopic) be put under atropine. In
 
 A Clinical Study. 55 
 
 certain young persons, with a moderate amount of 
 hypermetropia and spasm of accommodation which 
 entirely conceals the refractive error, there is eso- 
 phoria with periodic headaches, accompanied by 
 dizziness and nausea, which are relieved by correct- 
 ing the refraction as shown under atropine less .25 
 or .50; after a time the esophoria disappears entirely 
 and the glass is dropped without a return of the 
 symptoms. A certain amount of the hypermetropia 
 I consider the artificial production of the atropine ; 
 some patients may bear the full correction found 
 under atropine, but more do not; if a correction is 
 given which does not allow of clear distant vision 
 after the atropine is no longer used, the patient, 
 especially if still in the years of childhood, is likely 
 to look over the glasses for distant vision and thus 
 defeat the desired effect upon the muscles through 
 the accommodation. The effect of accommodation 
 upon convergence depends upon structural or edu- 
 cational connection between the centres in the brain, 
 and is very variable in different people. 
 
 It may be of interest to know the slow mental 
 processes by which the writer arrived at some of these 
 conclusions which he has set forth. Under an able 
 and thorough chief, during some years I tested the 
 refraction of several thousand patients under atro- 
 pine; as time went on and I found that the tests 
 without atropine tallied with those found or
 
 56 Heterophorias and Insufficiencies. 
 
 expected under atropine, the use of the drug was 
 dropped. Certain cases did not do as well as re- 
 garded the asthenopia and headache as formerly, 
 when atropine was used, and after rinding that this 
 resulted when the glasses were of no different 
 strength, and after eliminating the question of rest 
 to the ciliary muscle as an explanation, I found that 
 this result was due in certain cases to the relaxation 
 of accommodative esophoria, and began to use atro- 
 pine in esophoria cases again, as I had always 
 properly been taught to do in cases of convergent 
 squint. 
 
 A few cases show more esophoria under atropine 
 than before its use. Duane has explained that this 
 is due to extra efforts of accommodation induced by 
 attempts to contract the ciliary muscle. Reason- 
 able as is this explanation, I am not prepared to 
 accept it ; long ago, in the case of a child with con- 
 vergent squint, in which atropine increased the de- 
 formity, the mother told me that she had noticed 
 increase of the squint when her child was excited 
 or agitated, and that the girl had been very angry 
 about the drops, the eyes crossing more just as soon 
 as she knew that they were to be instilled. I have 
 been able in the cases under discussion to trace the 
 result to spasm of convergence, or weakness of 
 divergence, caused by nervous irritability or ex- 
 haustion; within a few weeks I had this occur, my
 
 A Clinical Study. 57 
 
 patient, a neurotic woman of forty, being in a very 
 excited state because the atropine had dried her 
 throat and kept her awake; at the beginning of the 
 examination under atropine esophoria had increased, 
 but at the close when the patient's excitement 
 had gone down the esophoria had decreased with 
 it. 
 
 Cases of accommodative esophoria may occur up 
 to the age of fifty-five years. In hypermetropic 
 presbyopes with esophoria spasm of accommodation 
 may be suspected when the glass required to correct 
 the presbyopia is stronger than usual. In cases of 
 accommodative or spasmodic esophoria operations 
 are, of course, contra-indicated, although frequently 
 performed. It is in just this class of cases that 
 tenotomy of the interni does the most harm. If it 
 is doubtful whether the case is accommodative or 
 muscular, and symptoms are not relieved by mere 
 correction of the refraction, prisms of just sufficient 
 strength to bring divergence up to the minimum for 
 that case (6. or 7.) may be given. It may be some 
 years before relaxation of the interni in these cases 
 causes the esophoria to disappear, but it usually 
 occurs, sooner or later. 
 
 In accommodative spasm, as in any other spasm 
 (if such exist) of the interni, strychnine, rest, and 
 general tonic treatment often increase the esophoria 
 and the ocular symptoms.
 
 5 8 Hetcrophorias and Insufficiencies. 
 
 It would be very erroneous for any one to sup- 
 pose that the typical symptoms of esophoria head- 
 ache, dizziness, or nausea, with a tendency to 
 periodicity occurring after prolonged use of the 
 eyes for distant objects are usually met with un- 
 accompanied by other ocular disturbances. In ac- 
 commodative esophoria especially are there often 
 other disturbances due to other ocular conditions ; 
 thus hypermetropia and astigmatism may cause 
 frontal and temporal headache for distance and near 
 work, and as in some other forms of esophoria, in- 
 sufficiency of the interni, or of convergence, may 
 cause asthenopia when near work is done, and 
 intense and constant headache may occur when 
 esophoria at the reading distance is present, which 
 error may be greater than that for distance. 
 
 Esophoria of Habit. Esophoria with Myopia. My 
 attention was first attracted to this class of cases in 
 June, 1894. A young lady of twenty-three years 
 came to me with the statement that she saw double 
 at times, and that all glasses given to her heretofore 
 caused much dizziness and discomfort. There was 
 myopia of 2.25 with a little astigmatism. Eso- 
 phoria of 8. increased to 12. with the glass (2 D.) 
 now being worn; convergence 25., divergence 5. 
 At 13* esophoria 5., convergence 45., divergence 
 1 1 . After atropine no change in refraction , esophoria 
 9., convergence 38., divergence 6. There was
 
 A Clinical Study. 59 
 
 apparent divergence; especial note should be made 
 of this; in myopia with esophoria there is apt to be 
 apparent divergence and the glasses are often centred 
 too broadly, while in myopia and exophoria there is 
 usually apparent convergence and the opposite error 
 -ef~toe great an .,o...c. in the glasses often occurs. 
 Glasses were ordered in this case with prisms 1.50 
 o.u. base out and o.c. in proper position; in other 
 words, 3 D's of prismatic action at the fixation lines. 
 These glasses caused no discomfort from the first, 
 but three months later the patient asked if she could 
 not have a less clumsy glass, as the thick outer edges 
 of the present one attracted attention. Esophoria 
 was now 6. This was accomplished by making the 
 p.d. narrower, the centre of glasses being 3 mm. 
 inside the lines of fixation, and no prism ordered. 
 Three weeks after this the left eye having a little 
 neuralgic pain when the glass was worn, esophoria 
 was found to be down to 2. without any glass, and 
 also with the last glass. The discomfort subsided 
 shortly after, and the patient brought in her mother, 
 who had high myopia and convergent squint, the 
 eyes converging for the far point of accommodation, 
 which was 2^" from the root of the nose, and not 
 diverging for distant objects. Convergent squint 
 with myopia had before this excited my interest, 
 and after concluding that it resulted from the habit 
 of fixing near objects, I found that this explanation
 
 60 Heterophorias and Insufficiencies. 
 
 and no other had been given by all writers who had 
 considered its causation. 
 
 After this esophoria and myopia attracted my at- 
 tention, and soon after I had an opportunity to 
 treat two sisters with this combination; one had 
 already had twelve operations done in the vain en- 
 deavor to straighten the eyes, the only result having 
 been much fatigue to the nervous system ; the other 
 had long been troubled with dizziness and had been 
 treated for " the liver " without relief to that symp- 
 tom. In the latter case, as the decentred lenses 
 ordered seemed to cause asthenopia, I ordered prisms 
 for the same muscular effect (combined with the 
 correction for the refraction, practically the same 
 that was being worn before I saw the case), and the 
 dizziness subsided slowly, disappearing within a 
 month. It returned about three years later, when 
 it was found that orthophoria was present instead 
 of esophoria of 3., and the prisms of I. base out were 
 taken from the glasses, when the dizziness and 
 asthenopia again disappeared. In the case of the 
 first sister there was esophoria of /., right hyper- 
 phoria of i., and it is not necessary to narrate the 
 details of the glasses decentred inwards, and the 
 good effects, except to say that in three years 
 the hyperphoria disappeared, as it was a converg- 
 ence hyperphoria, and esophoria was I. instead of 
 7. The father of these girls has hypermetropic
 
 A Clinical Study. 61 
 
 astigmatism and orthophoria, the mother has com- 
 pound myopic astigmatism and no appreciable devi- 
 ation, and another sister has myopic astigmatism, 
 with a little exophoria and excess of divergence. 
 
 Since these cases I have treated several scores of 
 others with myopia and the esophoria of habit, all in 
 the same way. This includes cases in which I had 
 formerly failed to appreciate the condition. As a 
 rule convergence is not excessive, and there is some- 
 times asthenopia for near work from insufficiency of 
 convergence; there is a fairly definite relation be- 
 tween the amount of myopia and esophoria; I de- 
 centre the glasses from 2 to 4 mm., so that there 
 is prismatic action at a distance with the prisms base 
 out, and usually some prismatic action in the oppo- 
 site direction for reading distance. This is not done 
 at haphazard ; the object is to get the least prismatic 
 action that will cause comfort to the patient, in the 
 expectation that improvement or cure of the devia- 
 tion will result as the eyes become accustomed to 
 fixing at a distance. The trouble occurs in persons 
 who have gone with their myopia uncorrected in 
 youth ; the symptoms in some cases do not begin 
 until glasses are worn, and may pass off without 
 any especial attention to adjustment of the lenses, 
 although not infrequently they persist. The most 
 usual symptom is dizziness with distant glasses, 
 occasionally headache, and I have seen one case of
 
 62 Heterophorias and Insufficiencies. 
 
 conjunctival congestion and blepharitis marginalis. 
 In this latter case a patient whose refraction had 
 been corrected returned to me because of increas- 
 ing eye strain. For the esophoria, which had pre- 
 viously been ignored, appropriately centred glasses 
 were ordered. I had no chance to verify the cor- 
 rectness of their manufacture, and nearly a year 
 later my patient returned, complaining that the 
 glasses had done him no good. The feeling of 
 strain and the lid trouble were worse, and I found 
 that his optician had taken the liberty of correcting 
 my error about the centre, or paid no attention to 
 the directions ; I saw that the lenses were decentred 
 as I wished, after which the symptoms promptly 
 subsided, and the lid congestion as well. 
 
 It will be noticed that a distinction was made in 
 two of these cases between prisms and decentred 
 lenses; I have given up any attempt to keep up 
 such a distinction in clinical work, except for certain 
 purposes, as when I find it much easier mentally, as 
 above shown, to fit a decentred lens than figure 
 prisms, or when, as in the case where vertical pris- 
 matic action is desired, I order prisms instead of 
 decentred lenses because I find this method easier 
 as well as more likely to insure correctness in the 
 work of the optician. The decentred biconvex lens 
 portrayed in books which state that such a glass is 
 equivalent to a prismosphere is dissimilar to the
 
 A Clinical Study. 63 
 
 glass ground by the manufacturers when spheres 
 and prisms are ordered in combination, as the latter 
 has one plane surface and may be considered as a 
 decentred plano-convex or concave lens. It is cer- 
 tainly wrong to consider such lenses as identical, 
 or a decentred meniscus as the exact equivalent 
 of either ; the differences are not only optical, 
 but prismatic as well when the eyes are turned 
 toward the periphery of the glass, yet the pain in 
 one eye caused in the patient above mentioned 
 when prisms were replaced by decentred lenses 
 should be referred to the different position of the 
 weak oblique cylinder in the lens, or some optical 
 influence, rather than difference of prismatic action. 
 It is only by consideration of such points that re- 
 ported cases of asthenopia relieved by toric lenses 
 in place of the usual kind, or a change of frames for 
 the glasses, can be given any value. 
 
 In muscular asthenopia we are dealing largely 
 with subjective symptoms caused by variation in 
 physiological and anatomical conditions; the con- 
 servative observer, until he or some member of his 
 family suffers from severe muscular asthenopia, is 
 apt to remain somewhat skeptical regarding the im- 
 portance of these difficulties, to regard a necessarily 
 artificial classification with some suspicion, and may 
 question the propriety of the introduction of a sepa- 
 rate class for cases which it might seem possible to
 
 64 Heterophorias and Insufficiencies. 
 
 include under old headings by means of some elas- 
 ticity of distribution ; yet the myopic esophoria of 
 habit has strong claims for recognition as a clinical 
 entity ; when it is recognized and considered in 
 glass corrections it is easily treated and benefited ; 
 when not, the fatigue of the externi often continues 
 and the symptoms may go on from bad to worse. 
 The esophoria is out of all proportion to the weak- 
 ness of divergence, and exceptionally may be in- 
 creased by stimulation to the accommodation when 
 concave glasses are worn. Thus it will be noticed 
 in a test given above that esophoria of 8. increased 
 to 12. with the correcting glass, while divergence of 
 6. remained unchanged. It will also be noticed that 
 prism i. only was ordered ; I never order a prismatic 
 effect in such cases which increases divergence to 
 more than 8. no matter what the esophoria. I fol- 
 low the same rule in all forms of esophoria, but in 
 no other is there any such disproportion between 
 esophoria and divergence after correction of the 
 refraction as in the esophoria of myopia. It must 
 always be kept in mind when prisms are ordered 
 that the prism strength is added to the muscular 
 power in the direction of the base and deducted 
 from that in the direction of the apex. 
 
 Passing over a considerable number of these cases 
 which present no special features it may be proper 
 to present a case with a fairly complete history
 
 A Clinical Study. 65 
 
 which showed the deviation and its effect to a 
 marked degree ; in view of the astigmatic element in 
 some of these cases it may be well to state that a con- 
 siderable number had the condition, the symptoms, 
 and the results without any astigmatism being found. 
 A hard-worked financier of forty-eight years had 
 been ordered sph. 9. right eye, 8.50 left, in 
 the spring of 1898, by a careful ophthalmologist of 
 high standing. He had signs of nervous fatigue 
 with some dyspepsia, but his most troublesome 
 complaints were of headache, mostly posterior and 
 basilar, and attacks of vertigo, without falling, when 
 attempts were made to look at distant objects. 
 His physician, having found no relief to his symp- 
 toms after a summer's vacation, concluded to resub- 
 mit him to an eye examination, and I saw him in 
 October, 1898. Vision with the old glasses (62 mm, 
 o.c.) wasf$ o.u. With 9. 50 and 9. ^cyls. i. 
 and .75 axis 90 in the right and left eyes respec- 
 tively V. = $- -f- in each. The eyes without glasses 
 showed an indeterminate amount of esophoria and 
 convergence; divergence I. and homonymous diplo- 
 pia under a red glass. There was right hyperphoria 
 of i., but the natural sag of the glass corrected this. 
 It was found that with the glasses at 56 mm. o.c. 
 orthophoria was at least temporarily present, and 
 they were thus ordered, a near glass less the presby- 
 opic correction being ordered with o.c. at 60
 
 66 Heterophorias and Insufficiencies. 
 
 as convergence was weak. This was done without 
 making unnecessary tests, as the already prolonged 
 examination had pretty well exhausted the patient. 
 The glasses caused much distress at first, but this 
 wore off, and the vertigo and severe headache were 
 relieved within a week. Nine days later the eyes 
 with the glass on showed for distance orthophoria, 
 with convergence 20., divergence 7. It is well to 
 note that the prismatic action of the glass upon the 
 eyes was 4., and also to call attention to the fact 
 that the hyperphoria was no doubt one cause for the 
 inco-ordinate action of the muscles of the eyes with- 
 out glasses, and perhaps had a contributing influ- 
 ence in producing symptoms; as to the astigmatism 
 as a cause of the vertigo this was thrown out, since 
 a duplicate pair of glasses were made later by the 
 patient's optician at 60 mm. o.c. and they brought 
 back the vertigo quickly; another similar mistake 
 was made later, with the same result. When the 
 eyes (or externi) were fatigued, as after attendance 
 at theatre, the esophoria partly returned with a 
 feeling of ocular fatigue, and about 2. of esophoria 
 could be found the next morning (with the glass 
 worn). This patient had clonic blepharospasm on 
 the left side and I treated his conjunctivitis and 
 blepharitis ; when this failed to relieve the twitching, 
 as a little more astigmatism had become manifest in 
 the left eye, I ordered a cylinder .25 stronger for
 
 A Clinical Study. 67 
 
 that eye. In June, 1899, the patient returned, as 
 he had begun to have some increasing discomfort 
 from his eyes, and he had been warned to expect 
 that as his esophoria disappeared ; he reported that 
 his blepharospasm, headache, and dizziness had re- 
 mained away after the last glass was worn, and his 
 ability to read without fatigue had gradually im- 
 proved. I found hyperphoria 2. (i. being corrected 
 by the glass). With the glasses on there was now 
 exophoria of 2., divergence of 10. New glasses 
 were ordered at 60 mm. o.c. with vertical prism I. 
 (base up, left eye), and the patient told to report if 
 not entirely comfortable. This case is the only one 
 seen by me, except the first one mentioned, in which 
 periodic squint with diplopia occurred and the only 
 one in which hyperphoria increased during the time 
 the case was under observation. 
 
 Full correction of the refraction is indicated to 
 give the best distant vision and stimulate proper 
 binocular fixation at a distance, and operations are 
 contraindicated in the esophoria of habit, which 
 occurs always, or nearly always, with myopia. 
 
 Muscular Esophoria. Esophoria from muscular 
 causes is due to excess of the interni or insufficiency 
 of the externi, and may occur with any or with no 
 error of refraction. In the first condition conver- 
 gence is powerful, divergence may be secondarily 
 omewhat weak, nervous irritability or strychnine
 
 68 Heterophorias and Insufficiencies. 
 
 increases the defect, and there is esophoria also for 
 near points unless insufficiency of convergence co- 
 exists. It may have been noticed that a distinction 
 is made between insufficiency of the interni and 
 externi, and insufficiency of convergence and diver- 
 gence; by the first terms I mean that there is a 
 muscular defect, by the latter a deficiency, shown 
 by the tests, of an associated action, which may be 
 muscular, nervous, or secondary to an error of re- 
 fraction. For instance, insufficiency of convergence 
 may be due to optical, accommodative, or general 
 nervous causes, excess of the externi, fatigue, or 
 insufficiency of the interni. Whether the oft- 
 mentioned spasm of convergence occurs without 
 excess of the interni, or insufficiency of the externi, 
 except in general disease, as meningitis, hysteria, or 
 chorea, or from local conditions, as from hyper- 
 metropia, hyperphoria, or improper glasses, is some- 
 what doubtful. There are rare cases which show 
 good balance of the ocular muscles and normal 
 divergence at times, which at others show esophoria 
 and weak divergence. Probably these are mostly 
 instances of latent esophoria becoming manifest, 
 like the other more numerous cases in which eso- 
 phoria is increasediunder just such general conditions. 
 It would be as rational to refer them to exhaustion 
 of divergence as spasm of convergence, the excess of 
 convergence being*simply a secondary result.
 
 A Clinical Study. 69 
 
 In cases of esophoria and excess of convergence 
 it is well to treat the deviation with caution, espe- 
 cially when hypermetropia coexists, using atropine 
 and attempting to relax the interni ; over-correction 
 of hypermetropia, or convex glasses for reading in 
 non-presbyopic cases, I do not particularly favor, 
 although the latter plan may sometimes be followed 
 with benefit. Prisms do well in the proper cases; 
 those in which the insufficiency of divergence and 
 the esophoria practically agree, and the muscular 
 condition for far and near are similar and prisms of 
 from i. to 2. over each eye nearly correct the diffi- 
 culties. In such cases three fourths or even all the 
 deviation may be corrected, the prism being ordered 
 in combination with the glass properly correcting 
 the refraction. In cases where the deviation tends 
 to increase, and prisms having been of relief are so 
 no longer, a tenotomy of one internus, perhaps fol- 
 lowed by a tenotomy of the other later, may be in- 
 dicated. The operation is similarly done to that for 
 hyperphoria, but usually needs to be complete. In 
 these operations strength is sacrificed for position, 
 convergence is usually weakened for a time out of 
 proportion to the good effect upon the esophoria, 
 and near work is apt to cause considerable discom- 
 fort for a week or two at least, even when the opera- 
 tion was done delicately. After this the severe 
 headache and symptoms are likely to be relieved,
 
 70 Heterophorias and Insufficiencies. 
 
 and although from the nature of the anatomical 
 conditions the esophoria is prone to return, weeks, 
 months, or years later, the headache and other 
 symptoms may not return. I am not conscious of 
 reason for regret in having done this operation in 
 the few cases in which I thought it necessary, but I 
 have treated a considerable number of post-operative 
 cases after they had passed out of the hands of col- 
 leagues, and I am not highly enthusiastic about the 
 results. 
 
 Most cases of muscular esophoria are, in my 
 opinion, due to insufficiency of the externi. Strych- 
 nine sometimes will help the asthenopia in these 
 cases; divergence is 4., or less, and convergence is 
 not excessive. The proper operation is an advance- 
 ment of an externus, picking out the weaker if this 
 can be done, as is often possible. The usual ad- 
 vancement for insufficiency is a detachment of the 
 central part of the muscle from its insertion, loosen- 
 ing of the subconjunctival tissue toward the cornea, 
 and the tightening and tying of a single horizontal 
 stitch which is passed through the middle of the 
 muscle near its cut end and the tissue above the 
 sclera up to the corneal margin. This single stitch 
 is entirely effective for the readvancement of a teno- 
 tomized muscle when the effect is too great, but for 
 cases where the opposing muscle is strong I prefer to 
 lift the muscle upon a tenotomy hook after making a
 
 A Clinical Study. 7 1 
 
 small opening above and below, and then pass the 
 needles at each end of a stitch through this upheld 
 fold toward the cornea, grasping conjunctiva and 
 muscle in a loop which holds more than half the 
 breadth of the muscle. The stitch is tightened, 
 and tied when orthophoria is obtained ; the result is 
 certain and permanent, and no bad result follows 
 should the stitch cut through, as it may occasionally 
 after some days. The operation is easy and pain- 
 less, and the fold in the muscle disappears gradually, 
 leaving the effect of the operation with no deformity. 
 Notwithstanding the good points about this advance- 
 ment it is not likely to come into general use, as it 
 is not so picturesque as some others at the time 
 of and immediately following the operation. The 
 stitch of an advancement should be kept in place 
 for five or six days, the eye being kept bandaged. 
 Motions of the eyes are uncomfortable because of 
 the stitch, and are avoided by the patient while it 
 remains in position, so I advance, or, strictly speak- 
 ing, fold, a muscle in my office, using no speculum, 
 and let my patient go home with a single bandage. 
 It is absolutely necessary to test the eyes at inter- 
 vals while doing tenotomies and advancements for 
 heterophoria, and this cannot be so well done if the 
 patient does not sit up for the operation in the office. 
 I find confinement in bed unnecessary. 
 
 It will be seen by the above that the old motto
 
 72 Heterophorias and Insufficiencies. 
 
 " It is better to be sure than sorry " applies to the 
 treatment of esophoria. I am in no greater hurry 
 to operate in these cases as time goes on than I was 
 formerly, and I am constantly surprised by the im- 
 provement in, and disappearance of, certain eso- 
 phorias without operation where such a result could 
 hardly have been predicted. Any centra-indication 
 will deter me from operation in these cases, and I 
 will here mention the case of an ophthalmologist 
 who had suffered severely for ten years from extreme 
 asthenopia and headache, mostly temporal and fron- 
 tal. This gentleman had consulted colleagues in 
 various cities about his ocular muscles and the last 
 one had proposed to straighten his physiological 
 vertical meridian, which tipped a little ; this last 
 opinion immediately gave me a clue, as I had seen 
 such cases before. The patient was wearing -\- I. 
 and 1.25 cyls. axes 90, which he had fitted, and 
 which all the consultants had accepted without spe- 
 cial investigation, and he had astigmatism which 
 was most perfectly corrected by cyls. -|- 1.25 and 
 1.75, axes 85 and 100 respectively. There was 
 decided vertical insufficiency of the lids, with con- 
 junctival congestion and blepharitis marginalis. At 
 twenty feet esophoria 2., convergence 16., diver- 
 gence 4. At 13" exophoria 10. and upwards, from 
 convergence insufficiency ; convergence 25., diver- 
 gence 14. There was no hyperphoria, and I told him
 
 A Clinical Study. 73 
 
 that I was conscious enough of my limitations to let 
 the muscles alone in all such cases as his, even if the 
 symptoms were more indicative of a muscular cause 
 than in this. I ordered the proper cylinder and told 
 him to treat his blepharitis, for whether the com- 
 pression theory be true or not, certainly asthenopia 
 comes from lid irritation in some cases; advised 
 strychnine to be used for the insufficiency of con- 
 vergence and the effects noted. The latter treat- 
 ment had of course already been tried. This 
 physician followed the first two suggestions, and 
 reported with apparent delight one week later, be- 
 fore he left for home, that he and his eyes had not 
 been so comfortable for years. There was no change 
 in the muscle test. It is doubtful whether those 
 eyes now have the comfort and endurance that 
 would be likely to be present in a case with strong, 
 well-balanced ocular muscles, yet a moral of a certain 
 sort may be drawn from the history. 
 
 It may be well here to call attention to the fact 
 that occasionally cases with weak externi momen- 
 tarily overcome prisms base in far in excess of those 
 which represent the real muscular power, while 
 rather more often just the opposite condition obtains 
 in eyes with abnormally strong externi. For in- 
 stance the externi may overcome prism 7. or 8. as 
 the test is first made, yet, in case they are weak, 
 diplopia quickly results should the prism be kept
 
 74 Heterophorias and Insufficiencies. 
 
 before the eyes, after which it is found that weaker 
 prisms are not overcome ; on the other hand with 
 strong externi prisms which at first produce diplopia 
 are overcome soon after, and divergence may thus 
 turn out to be much in excess of that which a rapid 
 and superficial test would have shown. This tendency 
 to concealment of latent deviations results from the 
 very nature of the case; these eyes are not only 
 forced into binocular fixation, but necessarily also 
 in exercising that faculty into a condition which 
 would be orthophoria if our tests should not succeed 
 in relaxing the strain put upon the weak muscles. 
 In measuring muscular ability endurance should be 
 considered more than temporary strength.
 
 CHAPTER IV. 
 
 EXOPHORIA. 
 
 THE headache of exophoria may only occur 
 when near work is done, or is increased by 
 near work unless there is divergent squint for near 
 points. It may be frontal, general, or consist of 
 pain in the posterior cervical region, and be accom- 
 panied by dizziness or nausea. There may be rapid 
 exhaustion of the eyes for near work, with or without 
 headache, from exophoria and weak convergence, 
 and sometimes the symptoms may be produced by 
 simple convergence for a near object or tests with 
 prisms base out. This production of symptoms by 
 prisms which bring a strain upon the weaker muscles 
 is not confined to exophoria, but is more easily de- 
 tected in this than in other deviations. For these 
 reasons weak convergence was the first of the in- 
 sufficiencies to be recognized, and has received an 
 amount of attention not as yet accorded to the more 
 obscure but not less potential muscular weaknesses. 
 As will be noted above, the asthenopic symptoms 
 in esophoria have nothing distinctive of the source, 
 
 75
 
 76 Heterophorias and Insufficiencies. 
 
 since combinations of other muscular and refractive 
 errors may cause them. 
 
 While divergence as an associated action has un- 
 doubted claims to a cerebral centre, yet I am posi- 
 tive that in normal conditions it cannot be forced 
 beyond a well-known limit set by habit and the 
 exercise of binocular fixation. I accept unquali- 
 fiedly the dictum of Hansen Grut that divergence 
 of the visual lines cannot be produced at will 
 and when found must result from abnormality, but 
 that latent divergence is often concealed by con- 
 vergence which exists both as a voluntary and reflex 
 act. 
 
 Exophoria always means then comparative excess 
 of strength of the externi, or of divergence (although 
 not necessarily as a permanent condition), if we keep 
 in mind the fact that the eyes tested at nearer points 
 than infinity may not converge for the test distance. 
 Thus for twenty feet if parallelism for infinity is 
 present and fixation is for infinite distance, either 
 through lack of accommodation in myopia or for 
 any other cause, it will take about a I. prism, base 
 in, to produce vertical equilibrium. The men who 
 originally stated that the difference between twenty 
 feet and infinity could be ignored in testing the 
 ocular muscles little foresaw that this would some 
 time be applied to tests with weak prisms. 
 
 Exophoria of I. at twenty feet I have often seen
 
 A Clinical Study. 7 7 
 
 occur in eyes where every other consideration led 
 me to consider the action of the ocular muscles 
 normal; more than that amount represents a real 
 tendency to divergence, and with exophoria r. only, 
 manifest, there may be any amount latent. 
 
 Accommodative Exophoria. Accommodative ex- 
 ophoria can only occur with myopia, unless it is 
 produced by too strong convex lenses in hyper- 
 metropia, or is acquired in the same manner from 
 reading glasses in presbyopia. In myopia the 
 exophoria will only disappear in young persons 
 when full correction is ordered, and in later life be- 
 comes permanent, although in an occasional case it 
 yields somewhat to correction of the refraction in 
 patients up to the age of forty and a little beyond 
 it. There is of course no intention on my part to 
 deny that certain anatomical conditions assist in the 
 production of exophoria and excessive divergence 
 in myopic cases. In cases of true accommodative 
 exophoria there is likely to be little or no increase 
 of divergence for distance, although prism conver- 
 gence may not be up to the standard, while exopho- 
 ria and weakness of convergence for near points are 
 out of proportion to these conditions for distance. 
 In fact it is the old, well-known condition of relative 
 divergence. 
 
 These cases are so well known and have been dis- 
 cussed so often, that anything I have to offer may
 
 78 Heterophorias and Insufficiencies. 
 
 be briefly stated. To prevent exophoria and insuffi- 
 ciency of convergence in myopia the refraction 
 should be fully corrected ; at a later period full cor- 
 rection, the glass being worn all the time, will give 
 stimulation to the convergence and favorable pris- 
 matic action for near work. Fortunately this class 
 of cases are not troubled much with muscular as- 
 thenopia unless there is an evident muscular defect 
 for distance which admits of operation, an astigma- 
 tism which admits of correction, or nervous exhaus- 
 tion of convergence power which needs appropriate 
 general treatment. Perhaps the following will serve 
 as a fairly typical case of accommodative exophoria. 
 An athletic schoolboy, aged fourteen at the time of 
 my first examination, October i, 1898, had f$ o.u., 
 with sph. 1.25 ^ cyl. .5 axis 105 R., sph. 
 1.50 L. = -. Exophoria 3., no asthenopia. 
 Further examination of refraction and muscles con- 
 sidered unnecessary. The glass ordered was only 
 worn in the schoolroom, and on December 22, 1899, 
 the myopia had increased to 2.25 o.u., with astig- 
 matism as before in the right eye. Exophoria 4. 
 As I supposed this to be a good sample case of ac- 
 commodative exophoria the muscles were further 
 tested in order to give the tests here. Convergence 
 at twenty feet, 12., easily brought up to 25. as soon 
 as the patient was shown how to converge; diver- 
 gence, 7. For 13", exophoria 10., 12., or more; a
 
 A Clinical Study. 79 
 
 test for the near point of convergence showed fixa- 
 tion at first at 10", but when the patient was told to 
 fix his attention and turn the eyes in for the pencil 
 he had no difficulty in converging to within 3" and 
 holding the eyes in that position. Cases of this 
 sort are, in my opinion, exophorias without muscu- 
 lar insufficiency ; they are more likely to have mus- 
 cular asthenopia from overwork than those cases of 
 myopia in which the eye muscles become more 
 correctly adjusted to the new accommodative con- 
 ditions, unless binocular fixation for near objects is 
 sacrificed. 
 
 The production of accommodative exophoria by 
 means of convex glasses is a common occurrence and 
 can in many cases be avoided. It frequently occurs 
 from full correction of the hypermetropia found 
 under atropine, and over-correction of hypermetro- 
 pia of about .50 in cases in which atropine has not 
 been used is of no uncommon occurrence. Patients 
 sometimes accept an over-correction of about .50 
 when hypermetropic, especially if after each eye is 
 tested separately the highest correction is forced 
 with both eyes open, the test letters with the glasses 
 perhaps appearing somewhat faded or washed out, 
 although vision is not diminished. I have in this 
 manner occasionally succeeded in getting a stronger 
 glass to correct hypermetropia than could be ob- 
 tained later with the eyes under atropine. Another
 
 8o Heterophorias and Insufficiencies. 
 
 class of cases in which accommodative exophoria 
 occurs are those in which (perhaps under atropine) 
 the spherical lens which represents the meridian of 
 greatest hypermetropia, is accepted with vision of 
 f$, or so, while the addition of a weak concave 
 cylinder would give better vision. In other words, 
 there is a small amount of astigmatism, and the 
 spherical over-correction given results in an artificial 
 myopic astigmatism. I have noted several cases 
 during the past year in which exophoria was pro- 
 duced or increased by over-correction of hyperme- 
 tropia and prisms base in had been added to the 
 glasses for the refraction, the total result to the 
 exophoria being an increase ; these cases had asthe- 
 nopic symptoms which were often relieved when the 
 convex lenses were made weaker and the prisms re- 
 moved. Analysis of the results in such cases show 
 them to be in part due to mental causes connected 
 with the difference in vision, in part to refractive 
 causes, and hence the effects of the difference in cor- 
 rection take on an exaggerated aspect if referred to 
 the muscles alone. In the case of a physician with a 
 little exophoria, who gave up medicine twenty years 
 ago because he found no glasses to relieve his asthe- 
 nopia, and who had been much better with the last 
 glasses ordered for him than any previous ones, the 
 first glasses (for he had saved them) turned out to be 
 convex cylinders .75 and .50 fitted under atropine;
 
 A Clinical Study. 81 
 
 the others were given on the same principle, except 
 the last, which was a concave cylinder, opposite 
 axis; this patient has since been able to use his 
 eyes freely and comfortably with treatment for the 
 muscular error. In cases in which the effect is out 
 of all proportion to the cause it is safe to refer 
 something to the imagination of the patient. 
 
 Accommodative exophoria from glasses also occurs 
 in presbyopic cases, and although the principles in 
 connection with accommodative exophoria as first 
 laid down by Bonders for such cases cannot be 
 successfully attacked, if any man expects to satisfy 
 his presbyopic patients by any attention to detail in 
 their glasses he will find himself sadly disappointed, 
 if he is alive to the results. Many of these patients 
 demand one glass with which they can see at far and 
 near points, and may consider an oculist incompe- 
 tent or obstinate if he fail to satisfy what they con- 
 sider a reasonable request. Convergence power is 
 usually weak in presbyopes ; convex glasses increase 
 this weakness by their effect upon the accommoda- 
 tion, and are usually centred too broadly, adding 
 an adverse prismatic effect to the other difficulties. 
 If muscular asthenopia already exists from weak 
 convergence the glasses may be centred in for a near 
 reading distance, but if the object is to avoid asthe- 
 nopia from glasses it will be safer to centre them 
 for the far point at which they may be used, since 
 
 6
 
 82 Heterophorias and Insufficiencies. 
 
 it is easier to exercise convergence than divergence, 
 for evident reasons. Thus suppose a glass of -|- 2.25 
 about 15 mm. in front of each cornea or 30 mm. in 
 front of the centre of rotation, with a base line of 
 60 mm. It would be safer to centre these glasses at 
 60 mm. - -^ mm. = 56 mm., i. e., for their far 
 point of 1 8" or 450 mm. instead of nearer, so as not to 
 increase the asthenopia caused by looking off through 
 them, of which there is usually so much complaint. 
 Glasses for near work may be centred by sighting, 
 in a similar manner to those for distant vision. 
 
 There is one point in addition to those which 
 have received attention elsewhere concerning bifocal 
 glasses, and that is that the principal complaint con- 
 cerning these glasses is of the distortion of objects 
 and diplopia at the upper part of the junction of 
 that portion of the glass used for distance and the 
 paster. While the formula for proper centring to 
 prevent this prismatic action depends upon the dis- 
 tance of the upper edge of the paster from the 
 geometrical centre of the whole glass, and is tedious 
 to work out mathematically, it is a comparatively 
 easy matter for the manufacturer to cut his paster 
 so as to neutralize prismatic action at its upper edge. 
 I have had no complaints and seen no bad results 
 due to the symmetrical prismatic action of glasses 
 of equal strength decentred upwards or down- 
 wards. It takes more knowledge than I possess to
 
 A Clinical Study. 83 
 
 successfully meet the demands of anisometropes 
 who desire comfortable non-distorting bifocals. 
 
 There is no definite agreement regarding what 
 should be considered normal balance for the ocular 
 muscles at a near point, such as the reading dis- 
 tance. Among healthy young adults with good 
 muscular strength and no particular refractive error, 
 who do not unduly use their eyes, as soldiers, 
 orthophoria is the rule at near points up to 12" or 
 less. This is indeed the best condition, yet is 
 found only exceptionally among patients applying 
 for eye treatment, with whom exophoria is the rule ; 
 while exophoria at a near point may easily occur 
 simply from relaxation of convergence and accom- 
 modation, I regard exophoria of over 2. at 13" as a 
 sign of probable weak convergence, and feel sure 
 that eyes with more dynamical divergence than this 
 are usually more or less asthenopic from weak con- 
 vergence. In this I differ from some other observers, 
 who regard 4. or 5. of exophoria at reading distance 
 as having no significance. 
 
 Much has been said regarding the production of 
 heterophoria by glasses, but nothing much about 
 the cases in which the eyes are forced into equilib- 
 rium notwithstanding the adverse prismatic effect 
 of a decentred lens, on the principle which causes 
 normal muscles to readjust themselves to differences 
 in the height of the eyes. The following case is an
 
 84 Heterophorias and Insufficiencies. 
 
 example of accommodative exophoria to which was 
 added an adverse prismatic action of over 6 D's from 
 decentred glasses, the whole error being rendered 
 latent by spasm of the weak interni. A young lady 
 with constant severe frontal headache, dizziness, 
 which had lasted for years, and chorea, was wearing 
 eye-glasses with 5.50 o.u. in such a manner that 
 a tight spring far forward on the nose brought the 
 p.d. (and o.c.) at 2", the base line being 2%" '. V. 
 O.U. = f$. There was weak convergence for near 
 points, but at 20 feet there was no appreciable 
 heterophoria, convergence 14., divergence 7. Sph. 
 6. at 2%" o.c. was ordered, and one month later 
 there was esophoria 3., convergence 12., divergence 
 8. at 20 feet. Orthophoria at 13" with convergence 
 30., divergence 14. The headache was no better 
 and I began to doubt my diagnosis of exophoria 
 and spasm of convergence from improperly centred 
 glasses, and favored choreic spasm, or accommoda- 
 tive spasm from concave glasses, more than I had at 
 first ; however I persisted, and one month after the 
 last examination exophoria of 2. with convergence 
 of 30. and divergence of 10. appeared and the condi- 
 tion of the eye muscles has changed but little 
 since; the headache became better at this time, and 
 each time it began to reappear the glasses were 
 ordered with o.c. 3 mm. farther out. The last order, 
 eighteen months after the first, was with the
 
 A Clinical Study. 85 
 
 o.c. 24". Divergence was then 11. with an ex- 
 
 o o 
 
 ophoria of 3., and with the glasses 1.50 of exophoria 
 still remains; the headache has not returned during 
 the year and a half since then, and as choreic move- 
 ments of the head and neck have disappeared, or 
 greatly diminished, the correcting glass has not 
 been further disturbed, or other eye treatment in- 
 stituted in the vain hope of helping the general 
 nervous difficulty. 
 
 The above points taken from the written history 
 of this rather unusual case do not show the main 
 reason why a diagnosis of spasm of the interni from 
 misplaced glasses was made in the first instance, 
 and I add from a clear recollection upon that matter 
 that the orthophoria at the first test was shown 
 without the glasses, with the glasses at 2" o.c., or 
 at 2-f" o.c., with the same action upon accommoda- 
 tion, yet a variation of 6 D's of prismatic action. 
 A side issue in the case was the demonstration 
 of the fact that people cannot be expected to 
 wear the nose-piece of eye-glasses in a position to 
 which habit and the shape of the nose have not 
 previously accustomed them ; if a new position of 
 the glass is desired it must be obtained by variation 
 of the length and shape of the posts connecting the 
 nose-piece with the glasses. 
 
 Muscular Exophoria. Exophoria with insuffi- 
 ciency of the interni or of convergence will be
 
 86 Heterophorias and Insufficiencies. 
 
 considered in the next chapter. Exophoria with 
 excess of divergence can be diagnosed by the 
 tests for the muscles at 20 feet. Divergence of 
 12. or more always constitutes excess, and from 9. 
 to ii. usually. Convergence commonly decreases as 
 age advances, and so soon as divergence excess with 
 asthenopia is known to be permanent there should 
 be a tenotomy of one externus, followed if neces- 
 sary by a tenotomy of the other. This should be 
 done on the principles already described, and in 
 marked cases of excess needs to be complete, and 
 not infrequently the attachments of the insertion 
 loosened, to produce orthophoria in the middle of 
 the field, with divergence of 7. or 8. A single 
 tenotomy of an externus carefully done upon a well- 
 developed muscle, care being taken to divide the 
 tendon at its insertion and not loosen the attach- 
 ments, will seldom give more than 5 D's of effect. 
 As a rule the effect at the time of operation dimin- 
 ishes but little, if any, at a later period, if the cut 
 muscle is put upon the stretch for a few days after 
 operation by forced convergence; the most effec- 
 tive method of accomplishing this is to have the 
 eyes converge for a near object, as the finger, 
 several times a day, and once a day have this done 
 while the eyes are armed with converging prisms ; 
 observations upon cases months or years after this 
 operation show in general no more increase of
 
 A Clinical Study. 87 
 
 exophoria than usually occurs in the natural course of 
 exophoria without operation. As a result of this 
 operation, increase in the power of convergence is 
 usually more than the decrease of divergence. 
 There is less apt to be this increased conver- 
 gence in myopic eyes, and in those where the 
 muscles are poorly developed. In the following 
 case increase of convergence was less than decrease 
 of divergence, and it is the only one in which I 
 have seen this occur. A poorly developed school- 
 boy of thirteen years of age, with myopia of 1.75, 
 showed in December, 1896, exophoria 2., con- 
 vergence 9., divergence 9. Nine months later exo- 
 phoria 3., convergence 7., divergence 9. Tenotomy 
 of the left externus was done and orthophoria re- 
 sulted. Six weeks later there was exophoria 2., 
 convergence 9., divergence 9. Three months later 
 tenotomy of the right externus, resulting a week 
 after in orthophoria, convergence 10., divergence 6. ; 
 one month later, exophoria .5, convergence 9., di- 
 vergence 8. This condition has continued since, 
 the severe headaches which the patient had after 
 studying having been better, but, as general treat- 
 ment including arsenic and strychnine has been 
 used, it is doubtful whether the operations can claim 
 any appreciable credit. 
 
 Another case of a similar character shows that so 
 little result as this cannot be foretold. This was
 
 88 Heterophorias and Insufficiencies. 
 
 the case of a man of twenty-five with severe and 
 constant headache made worse by near work. He 
 was of the same neurotic, ill-developed type, had 
 compound myopic astigmatism, which had been 
 carefully corrected one year before I saw him in 
 April, 1898, and had exophoria 4., convergence 6., 
 divergence 10. Tenotomy of the left externus gave 
 but temporary relief as orthophoria only lasted a 
 week; so one month after the first operation I 
 over-corrected the exophoria by tenotomy of the 
 right externus, attaining esophoria 2., convergence 
 14., divergence 3., changing to orthophoria with 
 convergence 16., divergence 7., in two months. 
 The proportions changed to 12. versus 8. nine 
 months after the second operation, when the patient 
 reported that he had only had a few slight head- 
 aches when he was tired and had overused his eyes. 
 In contrast to these let me give the most marked 
 case of increase of convergence I have seen, in eyes 
 with hypermetropic astigmatism of .50 in one eye 
 and .25 in the other. A young lady of twenty-four 
 years came to me in May, 1899, a f ter a season of 
 operations upon the ocular muscles done for the 
 purpose of relieving her of extreme headaches, dizzi- 
 ness and nausea. She was wearing sph. -j- I. with 
 prisms of 2.50 base in over each eye for reading; 
 exophoria of 5. at 13" being increased to 8. by this 
 combination. She had, at 20 feet, exophoria of
 
 A Clinical Study. 89 
 
 I D. with the phorometer, 7. or more with the 
 Maddox rod; convergence 20., divergence 20. I 
 first tried correction of the slight astigmatism, and 
 removal of the objectionable glasses, but with little 
 relief, so three weeks later I divided the left exter- 
 nus; all the exophoria I could get after this by any 
 test was 4., and the first result and that five months 
 after varied only I., convergence going to 38., diver- 
 gence to 16. This improvement in the eyes and a 
 summer's vacation gave no relief to the symptoms, 
 although general tonic treatment had been kept up. 
 I then divided the right externus, and the patient be- 
 coming exhausted and faint from a rather prolonged 
 operation in her neurasthenic state, a free tenotomy 
 left 2. of exophoria, although divergence was but 6. 
 and homonymous diplopia was present on the right 
 side of the field. One week later, as convergence 
 improved, the result was esophoria 2., convergence 
 40., divergence 5. In one month, however, there 
 was orthophoria for far and near with a convergence 
 of 65., divergence 9., at 20 feet. The action of 
 the muscles was now co-ordinate, dizziness and nau- 
 sea had disappeared and the general headache with 
 them ; the distressing pain at the nape of the neck 
 had not yet entirely disappeared, although it did 
 soon after, the patient reporting herself well two 
 months later and showing the same muscular condi- 
 tion as that last given. In this case reduction of
 
 90 Heterophorias and Insufficiencies. 
 
 divergence II D's gave increased convergence of 
 45. A contrast to this as regards result to the 
 symptoms before a good muscle test was obtained, 
 yet agreeing as regards improvement in converging 
 power, is shown by the case of a girl of nine years, 
 who had crossed diplopia under a red glass, and in 
 whom I did free tenotomy of the left externus, with 
 the result that two months later while convergence 
 for near work had improved, at 20 feet there was 
 convergence of 2. only, divergence of 20. Eight 
 months later there was convergence of 12., diver- 
 gence 14. Severe and frequent headaches had dis- 
 appeared since the operation. In these two cases 
 post-operative hyperphoria was temporarily pro- 
 duced and disappeared in a week ; a not very un- 
 common experience. 
 
 In contrast to these complete operations giving 
 slight results let me say that I have a few times pro- 
 duced convergent squint and homonymous diplopia 
 before an externus seemed to be completely divided, 
 and have usually advanced the cut muscle with good 
 result, by means of a single stitch tightened until 
 orthophoria in the centre of the field was produced. 
 In one case, however, the patient became hysterical 
 about the stitch and promised faithfully to let me 
 do anything 1 wished in the way of an operation 
 later if I would remove it. As I wished to watch 
 the effect, and the onus was on her, I left the muscle
 
 A Clinical Study. 91 
 
 as it was by drawing out the stitch, which had not 
 yet been tied. There was, strangely enough, no 
 dizziness following the operation, the headache 
 which had not yielded to correction of the refrac- 
 tion, or other treatment, was relieved, and two 
 months later the diplopia could not be obtained at 
 the periphery of the field except by means of a red 
 glass. A test four months after this showed ortho- 
 phoria. 
 
 In case it should seem strange that readjustment 
 should follow in some cases too little, in others too 
 much operative effect, let me say that in the former 
 class the exercises above described for a near point 
 are used, while in the latter near work is prohibited 
 for a time, but the eyes are encouraged to fix dis- 
 tant objects. This small detail of treatment would 
 be of little use, except for the principle that people 
 with strong desire for binocular fixation tend to 
 force the eyes into orthophoria in the centre of the 
 field, as soon as the muscular condition will per- 
 mit of such a thing ; let me say, however, that the 
 above cases are for me the exception ; in most of the 
 others orthophoria was the primary result of the first 
 operation. In such a case, if the effect decreases 
 later, when a second operation is done I over-correct 
 by an amount equal to the decrease which occurred 
 after the first operation. 
 
 Exophoria of 4. or more with more than 12. of
 
 92 Hetcrophorias and Insufficiencies. 
 
 divergence will usually require an apparently com- 
 plete tenotomy. By apparently, I mean that it is 
 difficult to cut across the tendon of a muscle with- 
 out loosening the subconjunctival tissue, or the at- 
 tachments of the muscle to the capsule of Tenon, 
 through a small opening in the conjunctiva, and be 
 sure of the complete character of the division, even 
 when the line of insertion to the sclera can be seen ; 
 a small band of fibres, deep and peripheral, may 
 easily escape notice. It should be remembered 
 that the object is to remove the muscular difficulty, 
 not to prove the division of a muscle. In weaker 
 muscles tenotomies which only partially divide the 
 tendon will produce results ; as these cases are often 
 of the neurasthenic type, I generally avoid operation 
 upon them and cannot speak so definitely of them as 
 of the class in which I find that division of the ten- 
 don nearly, or completely, in such a way as to avoid 
 too much retraction of the muscle, is necessary to 
 obtain a definite result. 
 
 It is by no means easy to tell in advance how 
 much a muscle will retract, hence the necessity of 
 graduating the operation by testing the eyes at inter- 
 vals. Every competent operator uses this principle 
 in cases of squint when he looks at the eyes to see 
 whether he has advancement or tenotomy enough to 
 reduce the deformity; in this case he is operating 
 for appearance, in the other for muscular balance.
 
 A Clinical Study. 93 
 
 In exophoria cases it is well to take the desired 
 strength of divergence as a guide in operating as 
 well as the production of orthophoria. 
 
 It is very important to consider hyperphoria in its 
 bearing upon exophoria and esophoria. The lateral 
 deviations may improve or disappear when hyper- 
 phoria is corrected, or they may require further cor- 
 rection ; the method already described of correcting 
 the hyperphoria with prisms, then testing the lateral 
 balance with the rod, also trying the effect upon 
 convergence and divergence, gives valuable informa- 
 tion but is not infallible. 
 
 Neurasthenia as a result of operations upon the 
 eye muscles is not uncommon, from the nervous 
 anxiety and traumatism, and it is well for the opera- 
 tor to get through by means of as few operations as 
 possible. If the symptoms are no better after a 
 couple of operations, it is just as well to inquire and 
 determine whether a neurasthenic asthenopia is not 
 replacing a muscular asthenopia, and treat the case 
 accordingly.
 
 CHAPTER V. 
 
 INSUFFICIENCY OF CONVERGENCE; NEURASTHENIC 
 
 MUSCULAR ASTHENOPIA; INEFFICIENCY OF 
 
 THE OCULAR MUSCLES. 
 
 IT has been a time-honored custom among oph- 
 thalmologists, to group all cases of asthenopia 
 of which they failed to understand the origin as 
 neurasthenic. In the United States a race of rest- 
 less adventurous explorers, fighters of Indians and 
 revolutionists, have, in the persons of their descend- 
 ants and successors, taken to city life, books, physi- 
 cal appliances, artistic paraphernalia, steam heat, 
 and other appurtenances of what they call education 
 and civilization, with the same result that obtains 
 when the country-bred boy settles down to sedentary 
 city life trouble with the digestion, circulation, and 
 nervous system. The first attempts at imitating 
 foreign civilization in this country resulted twenty- 
 five or more years ago in the thin, pale, nervous 
 young girl; as admiration for the civilization of 
 France began to be replaced by imitation of the 
 English style of life this type of woman began to 
 
 94
 
 A Clinical Study. 95 
 
 be replaced by the larger, stronger, rosier type in 
 which forced development of the bones, muscles, 
 and circulation was expected to properly adjust the 
 balance in the forced brain and nervous system, 
 with the result that nervous irritability with some 
 energy and endurance began to give way to neuras- 
 thenia and emotional disturbances of the nervous 
 system. In the first type by means of tonics, nour- 
 ishing food, fresh air, and exercise we expect to 
 meet the indications ; if in the course of a generation 
 or two the second is the result of this method, what 
 next ? 
 
 The undoubted soundness of the view that atten- 
 tion to hygiene is the key to development of the 
 nervous system as well as the other forms of tissue 
 cannot be questioned ; yet the occurrence of weak- 
 ness in the ocular muscles with other undoubted 
 evidences of lack of force, in the well-nourished and 
 apparently well-developed American youth of to- 
 day, show that nervous degeneration cannot always 
 be successfully combated by a general knowledge 
 that nourishing food, fresh air, and exercise tend 
 to develop the human animal. 
 
 The main point to be insisted upon here is that a 
 neurasthenic patient with muscular asthenopia is 
 not of necessity a case of neurasthenic muscular 
 asthenopia. The more neurotic a person is the 
 more likely he or she is to suffer from nervous
 
 96 Heterophorias and Insufficiencies. 
 
 symptoms referable to ocular defects, just as a case 
 of chronic gastric catarrh has more dizziness and 
 nausea from eye strain than one with better diges- 
 tion. Occasionally muscular and nervous signs of 
 exhaustion occur from excessive use of the eyes, 
 with hyperesthesia retinae and even displacement 
 fields of vision, in persons who have not shown evi- 
 dences of exhaustion in any other function than that 
 of vision ; as the exhaustion is mainly of nervous 
 tissue of the eyes and their cerebral connections, 
 these are properly to be considered as cases of neu- 
 rasthenic asthenopia, although general evidences of 
 nerve exhaustion are absent. Perhaps " neurasthe- 
 nopia " would be a proper term for them. 
 
 The type of muscular weakness which belongs 
 to the neurasthenic is that known as insufficiency of 
 convergence, or defective amplitude of convergence; 
 this latter term, with its positive and negative fac- 
 tors, is proper but formidable, and studies already 
 made under this head are of little clinical value as 
 regards diagnosis and treatment of heterophoria. I 
 here take the liberty of proposing the term " Ineffi- 
 ciency of the Ocular Muscles" for the class of cases 
 to be described ; inefficiency means lack of power, or 
 the desire for power, and exactly denotes the con- 
 dition of weak muscular action arising from lack of 
 development of muscles or of nervous tissue, fatigue 
 and lack of energy, or want of ambition, which
 
 A Clinical Study. 97 
 
 characterizes neurasthenic muscular asthenopia. 
 We often meet in the American youth of to-day 
 and in others broken down by worry or illness, such 
 conditions of the ocular muscles as follows: Ortho- 
 phoria or esophoria i. to 2., convergence 9. to 12., 
 divergence 3., 4., or 5. ; orthophoria or exophoria, I. 
 or 2., convergence from 6. to 8., divergence from 8. to 
 6. Fixation for a near point is weak and inadequate, 
 with exophoria at 13" from a few dioptrics up to 
 actual divergence of the lines of fixation. Sursum- 
 duction usually I. or 1.50. This condition may be 
 acquired, and if due to temporary general or ocular 
 fatigue consist merely of a relative insufficiency of 
 convergence, with little or no weakness or excess 
 of divergence, and yield rather easily to ocular rest 
 and general treatment with strychnine. More often 
 the condition is permanent, both the ocular mus- 
 cles and the brain centres being undeveloped, and 
 I regard this condition as shown by inefficiency 
 of the ocular muscles as one of the stigmata of 
 degeneration. 
 
 Occasionally the apparent lack of muscular power 
 is simply a sign of constitutional laziness and in 
 such cases will not cause pain and discomfort ; 
 sometimes there is a hysterical element, more or 
 less latent, and the muscular strength is variable. 
 Variation in the power of convergence and diver- 
 gence, except in cases of hyperphoria, or functional
 
 98 Heterophorias and Insufficiencies. 
 
 or organic nervous disease, does not seem to occur 
 to any extent in my cases of late years, perhaps 
 because the routine tests are made over and over 
 under the same conditions as regards the manner of 
 testing, and with precautions against variation. 
 
 In neurasthenic subjects the weak ocular muscles, 
 sensitive retinae, irritable reflex centres, and gener- 
 ally inefficient muscular and nervous force cause 
 undue susceptibility to slight physical variations 
 affecting the eyes, while the cerebral condition is 
 often such that general effects from slight local 
 causes may be exaggerated, distorted, or imagined ; 
 in treating such cases, although the underlying 
 principles are the same as in others, the point of 
 view should change so materially that they must of 
 necessity be considered as a separate class. For 
 them the use of tinted glasses should be discour- 
 aged ; the chemical rays of light, the most if not the 
 only injurious ones to the eyes, do not penetrate 
 glass to any extent, irradiation of light increases 
 with refractive error, and hence correcting glasses 
 are indicated if the patient's prejudices and nervous 
 condition will permit glasses to be worn. Strong 
 glasses may not be borne, even if they barely correct 
 manifest error, and care must be taken to guard 
 against strong or adverse prismatic effects. In a 
 few cases in which operations seemed indicated to 
 me I found the muscles ill developed, as might be
 
 A Clinical Study. 99 
 
 supposed from the nature of the cases and the re- 
 sults of tests for muscular power; such muscles may 
 be badly injured by tenotomy and cannot be much 
 strengthened by advancement. If lack of nervous 
 impulse is the cause of the inefficiency, or it is due 
 to temporary exhaustion of muscular or nervous 
 force where the muscles are well developed, opera- 
 tions are surely not indicated. Since operations are 
 of little or no use for the inefficiency, and may be 
 harmful to the neurasthenia, they could only apply 
 to the correction of slight heterophorias when such 
 are present and cannot be successfully treated in 
 some other manner; they would, therefore, be pref- 
 erably postponed until general treatment has failed 
 to relieve the asthenopia, and the general strength 
 of the ocular muscles has reached a maximum. 
 
 It must be kept in mind that one form of insuffi- 
 ciency yet remained to be considered when we 
 reached this chapter, insufficiency of the interni, or 
 convergence, without excess of divergence, not ac- 
 companying hyperphoria, nor accommodative, and 
 that this condition is neurasthenic and constitutes 
 inefficiency of the ocular muscles. Although, as in 
 the first case cited under the heading exophoria, it 
 may be seen that advancement of the interni appears 
 to be indicated, this operation at the best may 
 cause too much post-operative annoyance to be ap- 
 propriate to the neurasthenic condition, and we may
 
 ioo Hcterophorias and Insufficiencies. 
 
 be compelled to confine ourselves, when an opera- 
 tion is justifiable, to cutting some fibres of a superior 
 or external rectus for the correction of hyperphoria 
 or exophoria, which would be more formidable ex- 
 cept that in cases of inefficiency the operation is a 
 slight one, complete division of the tendon seldom 
 being necessary. 
 
 Extensive discussion of general treatment is be- 
 yond the province of this work. Strychnine is the 
 general remedy most applicable to strengthen mus- 
 cular and reflex action. It is given at first in small 
 doses, then the dose is increased from time to time. 
 It seems to me that in this manner we find just the 
 dose that may be borne by a patient, not that we 
 induce toleration for the drug. The remedy bene- 
 fits some cases quickly, others slowly, others not at 
 all; cases of orthophoria with insufficiency of con- 
 vergence, due to fatigue from excessive eye work, 
 do best with it, as previously stated ; cases of 
 esophoria with general nervous irritability do much 
 less well. Certain general conditions are a contra- 
 indication for strychnine, noticeably arteriosclerosis 
 with high arterial tension. 
 
 Decision regarding the comparative merits and 
 proper amount and character of rest and exercise in 
 the general treatment of these cases requires much 
 experience and nicety of judgment. It seems evi- 
 dent, however, that rest from that which fatigues or
 
 A Clinical Study. 101 
 
 irritates the nervous system, or rest to an overused 
 structure or organ, would be, of necessity, indicated. 
 It is hard for some of us to see any rational treat- 
 ment for the eye with structural or functional weak- 
 ness, suffering from symptoms brought on by strain 
 of the weak part from overuse, not founded upon 
 rest for the weary organ. Neuralgias in general are 
 treated by attempts to improve the health and give 
 rest to the painful part. Since the eyes are con- 
 stantly in use when the lids are open, we are unable 
 to obtain absolute rest without imperiling the gen- 
 eral health ; so we partially rest the ciliary muscle 
 and meet visual and retinal indications by correcting 
 the refraction, and attempt to give rest to the weak 
 muscles by means of prisms, while we try to obtain 
 a proper muscular balance by various methods. It 
 is not the insufficiency which causes asthenopia but 
 use of the insufficient muscles; insufficiency of the 
 externi gives rise to headache with the most certainty 
 when the eyes are used to look at outside objects 
 from the windows of a moving train, while if no in- 
 sufficiency exists for a near point the eyes may be 
 used for reading, upon the same journey, without 
 discomfort; reading from a prone position causes 
 trouble especially, or solely, in cases of hyperphoria. 
 In inefficiency the converging power suffers most; 
 the condition precedes the asthenopia, apparently, 
 as the weakness is congenital, or acquired from
 
 IO2 Heterophorias and Insufficiencies. 
 
 worry, illness, or the wear and tear of surgical in- 
 juries or operations, in the latter cases the asthe- 
 nopia and headache beginning after hard use of the 
 eyes for reading, or other near work, during conva- 
 lescence. Headache, dizziness, nausea, conjunctival 
 congestion, and pain at the back of the neck are 
 most in evidence with convergence. 
 
 Should it appear that we are indulging in an un- 
 necessary amount of detail in order to show that 
 rest is so important in the treatment of exhausted 
 ocular muscles, it must be remembered that there 
 was a time, perhaps forgotten by a younger genera- 
 tion, when a well-known American ophthalmologist 
 instituted a treatment for asthenopia consisting of 
 ocular gymnastics (and ointments for the forehead), 
 which was received by some with great enthusiasm 
 and expected by them to relieve all forms of eye 
 strain not evidently accommodative ; also, that forms 
 of exercise for the ocular muscles are still in use with 
 many statements on record regarding the increased 
 strength obtained, as shown by tests and relief to 
 symptoms. The first claim has been considered in 
 an early portion of this work; as to the second, 
 neurasthenia is essentially a chronic condition with 
 intermittent symptoms, and statements regarding 
 relief to symptoms are to be received with caution ; 
 they may, in fact, be a measure of the self-satisfac- 
 tion of the man presenting them, or an expression
 
 A Clinical Study. 103 
 
 of an evident appreciation of his efforts by his 
 patients, rather than an actual count of tangible re- 
 sults which is well-nigh impossible to make in cases 
 with subjective symptoms. 
 
 The general rule should be that eyes are not to 
 be used for near work after they show the slightest 
 signs of fatigue. When, as in my cases, tests for 
 convergence bear a definite relation to the ability 
 for near work, they may be used as a guide. Thus, 
 with prism convergence of 8 D's for distance, the 
 eyes are to be used at first not over five minutes 
 twice a day, this time to be increased with increased 
 convergence power, until with 16 D's the eyes are 
 used for near work half an hour four times a day. 
 
 We have already noted the effect of emotion 
 upon the ocular muscles, and incidentally it has been 
 suggested that those emotions which cause excite- 
 ment or irritability induce spasm of strong muscles, 
 while those which cause exhaustion increase insuffi- 
 ciency ; in this way latent heterophoria may become 
 manifest, or pseudo-heterophoria may be produced. 
 Nervous young women sometimes dread an examina- 
 tion of the eyes, and having a little asthenopia, are 
 fearful that this signifies some dread disease. Fear 
 not only dilates the pupil, but relaxes accommoda- 
 tion and convergence. This condition being limited 
 in duration, certain cases which show inefficiency 
 of the ocular muscles at a first test will show
 
 104 Heterophorias and Insufficiencies. 
 
 improvement of convergence at a later period, with- 
 out regard to treatment. The contradictory in- 
 dications to be met in treating the asthenopia and 
 convincing the patient that there is nothing the 
 matter with the eyes, may sometimes require mental 
 more than direct medical treatment. 
 
 When glasses are worn, especially convex ones, a 
 new relation is set up between accommodation and 
 convergence, and muscular asthenopia may result, 
 the condition being more intractable as age ad- 
 vances, and most complained of by neurasthenic 
 patients. To overcome the difficulty it is absolutely 
 necessary that the eyes should converge with the 
 glasses, and if a neurotic patient insists upon the 
 impossibility of using the eyes for near work, con- 
 verging exercises with the finger or with prisms may 
 possibly be indicated. These cases may be diag- 
 nosed by the increase of heterophoria with glasses at 
 a near point, when the centres are in the lines of 
 fixation for that point. 
 
 The division of asthenopia into retinal, from gen- 
 eral disease, accommodative, from errors of refraction, 
 and muscular is not sufficiently comprehensive. It 
 does not include the effect of certain materials upon 
 the eyes, as, for example, glazed paper ; operatives 
 who make white boxes with this material suffer from 
 eye strain which ceases with a change of occupa- 
 tion. Other causes of asthenopia, such as a bent
 
 A Clinical Study. 105 
 
 position of the head, use of the eyes immediately 
 after meals, poor position and character of the 
 illumination used, are also not included in the above 
 classification. We all know that somewhat modified 
 daylight from above and to the left and rear is de- 
 sirable, but the character of the artificial illumina- 
 tion which is least injurious to the eyes is still in 
 doubt. A belief in the bad effects of insufficient 
 illumination is well-nigh universal; that poor light 
 causes ocular discomfort is perfectly evident, yet it 
 is difficult to see how it could do the harm, func- 
 tionally or organically, that must come from excess 
 of illumination. In the medium limits of illumina- 
 tion, where increased light causes increase of vision, 
 the latter increases only about as the logarithm of 
 the former, and the excess of light is injurious to the 
 retina. If we look at the history of any nation, or the 
 comparative history of all, we see without exception 
 that asthenopia increases directly with the increase 
 in amount and intensity of artificial illumination. 
 Here we have the combination of causes which pro- 
 duce " neurasthenopia " or ocular exhaustion, with- 
 out regard to the nature of the defects existing in 
 the structure or dynamics of the eyes: the artificial 
 life which goes with artificial illumination, the ability 
 to continue using the eyes when they are fatigued 
 and should be rested, and the direct chemical effect 
 of improper light upon the exhausted retina.
 
 106 Heterophorias and Insufficiencies. 
 
 It may seem that these and some other considera- 
 tions herein presented have little, if any, direct 
 bearing upon the ocular muscles. This book is not 
 intended for those who can treat asthenopia success- 
 fully by ignoring the ocular muscles, or those who 
 can obtain the same happy result through these 
 muscles alone. 
 
 118 EAST 720 STREET, NEW YORK, 
 March 5, 1900.
 
 THE LIBRj 
 UNIVERSITY OF CALIFORNIA 
 LOS ANGELES
 
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