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Refraction
DIGEST OF THE LITERATURE. REFRACTION. THEODORE B. SCHNEIDEMAN, M. D. PHILADELPHIA. (Continued from January issue)
Crawford has addressed a questionnaire to 90 eye specialists of this country asking their practice as to the use of cycloplegics in refraction. A large majority considered such to be necessary, though there was some divergence as to the proportion of cases in which it need be employed. Homatropin and atropin were the drugs used with very few exceptions. In insisting upon the need of cycloplegics in refraction work, Clarke states that in the absence of a cycloplegic a different result can be obtained at every examination, as it is impossible to determine accurately the degree and axis of a weak cylinder. In proof of this he has carefully determined the refraction of many young patients before and after paralysis of the accommodation : in not a single case did the two agree. He maintains that inaccurate refraction which leaves a slight, but different error from that which was originally present, may cause eyestrain which had not been present before, because the ciliary muscle is now able to correct the new resulting error when it could not deal with the original larger one. CHANGE IN REFRACTION.—Risley
re-
ports a case in which the refraction, from having been hyperopic astigmatism, developed into myopia of —4 and —2.25 respectively in the two eyes, with vision 6/15 and 6/60, following increased tension with numerous exacerbations; and final almost sudden subsidence of the hypertension, in an aged woman subject to arthritis deformans. The change in the refraction was accompanied by obvious thinning of the anterior ciliary region and a groove like formation surrounding the cornea just back of the limbus with tension normal in both eyes. There
were no demonstrable changes in the crystalline lens to account for the increased refraction. MYOPIA.—To cure myopia, Bacchi advocates progressive pressure in the antero-posterior direction by means of the apparatus of Roger d'Ansan with a view to shortening and widening the globe. He reports favorable results following a few sittings. Among various phases of myopia brought to light in Masuda's statistics, the most remarkable is that in 20 per cent the myopia was found to be hereditary. Macular changes appear earlier and are usually of a more severe character in women than in men. Illustrations of various macular changes are appended. The vision with equal errors of refraction, and in spite of early and full correction, is apt to be lower in women than in men. Harriet Gage summarizes a study of myopia, including myopic astigmatism, from the Massachusetts Charitable Eye and Ear Infirmary during 1915. Of 1,524 eyes the refraction was below 3D in 56 per cent; 20 per cent were between 3 and 6D, and 20 per cent were cases of high myopia (from 6 to 15D). Only 2^2 per cent showed very high myopia, above 15D. Of 1,696 myopic eyes 54 per cent showed no astigmatism ; 36 per cent presented compound myopic astigmatism, and 10 per cent simple. The same paper deals also with the age, sex, visual acuity, including the sociologic as well as medical aspects of such patients, and should be consulted in the original. Muirhead opposes the doctrine that the action of the external muscles tends to raise the intraocular tension and to cause lengthening of the globe. He believes that the opposite is the case, in that the action of the muscles tends to
18
REFRACTION
cause an antero-posterior flattening. When the recti are divided, the eyeball moves forward, showing that it is held back by the tonicity of the muscles—an impulse not due entirely, he thinks, to the elasticity of the retroorbital contents, but partly to the elastic recoil of the eye itself. Another argument which the author takes up is afforded by the change in the apparent size of objects. According to the usual hypothesis, pressure is greatest when the eyes converge. As the eye must elongate under this pressure the apparent size of the image should enlarge. The author states that it diminishes. The author is greatly opposed to full correction of myopia, holding that persons wearing a full correction are always uncomfortable and suffer from eye-strain. The above is a short resume of some of the theses maintained by the author in his book. The reviewer believes that every one mentioned is inadequately proven and indeed leaves the question where it was. Those who desire to go into the subject from the author's standpoint must be referred to the work itself. In view of the wide prevalence of myopia in Germany (each year about 9,000 recruits in the Germany army are held back on account of eye affections, the great majority of which are myopes belonging especially to the better classes), the military authorities have attempted, immediately after the declaration of war, to perfect the military education of the younger classes by training exercises (among other factors) of distant vision, estimation of distance, etc. In this connection v. Ziegler relates his personal experience in such training. He had the myopes remove their glasses and exercise their distant vision on targets successively smaller in size. At the end of 6 months all were able to recognize the smallest of the targets. Other exercises in different maneuvers in maintaining straight or oblique directions of march, parallel or perpendicular courses, etc., were also practised with success. ASTIGMATISM.—Nordensen remarks that although the question, whether in
a given case the astigmatism should be corrected or not, occurs daily and is important and complex, it has been little debated in ophthalmic literature, and the text-books give only vague directions on the subject. (This may be true in Europe, but there is certainly iio lack of literature upon the subject in America, in which country there is substantial agreement among oculists generally upon the point in question.— Rev.) This writer reviews the rules for and against the correction of astigmatism. In general, he thinks correction is needed only if it increases visual acuity, (i) where such increase is needed, such as may be called for by the individual's occupation or during the period of education in children, (ii) Asthenopia—chiefly of two kinds: ( a ) accommodative asthenopia. He refers this form to the contraction of the pupil which occurs during accommodation and improves definition by cutting off the peripheral rays; this advantage is obtained by some ametropes by excessive accommodation, bringing the p.p. too close and so interfering with sharpness of vision for near work. The patient therefore relaxes the accommodation, the size of the pupil increases, he reverts again to accommodation, and this alteration produces fatigue and strain, (b) Eyelid Asthenopia. This kind of asthenopia is due to strain of the orbicularis muscle, which can be used to correct inverse astigmatism by the pressure it is capable of exerting in a vertical direction upon the globe. As much as 2 or 3D. can be compensated in this way, but the excessive action of the orbicularis leads to fatigue, (c) Dangers to the eye involved by astigmatism, as favoring the development of strabismus or myopia. In nervous affections, such as epilepsy, migraine, headache, etc., the astigmatism should also be corrected. Among the contraindications he includes: the inconvenience of wearing glasses, when, for instance, one eye is normal and the other astigmatic; nonimprovement of visual acuity after the correction has been worn for some time; intolerance of correction, as in elderly patients in whom the principal meridians do not coincide
DIGEST OF THE LITERATURE
with the vertical and horizontal planes, etc., etc. He rejects the view which has been advanced in recent years as a reason for not correcting astigmatism in children that the anomaly may even disappear spontaneously if it is left uncorrected. EFFECTS OF UNCORRECTED REFRACTIVE
ERRORS.—Carhart insists upon the necessity of careful examination of the eyes of school children, particularly those who appear to be deficient in their studies. He summarizes the result of the examination made 20 years ago, of 1,000 school children of various ages in two village schools; not only those suspected of ocular defects but all the children in the classes from kindergarten through high school. The children were largely American born, in whom the errors of refraction are less common and of lower degree than among a foreign-born city population. He found of emmetropia 13 per cent, hypermetropia 36.20 per cent, C. H. astigmatism 44 per cent, myopia 1.40 per cent, C. M. astigmatism 3.50 per cent, mixed astigmatism 1 per cent. The following table shows the percentage by ages of the various errors in the same 1,000 children: 5 to 8 9 to 12 13 to 18 yrs. yrs. yrs. Emmetropia 10.00 16.43 14.33 Hypermetropia .. 53.48 37.27 22.87 C. H. astigmatism 33.48 40.05 58.55 Myopia 0.87 1.85 1.17 C. M. astigmatism 71.74 3.01 5.26 Mixed astigmatism 0.43 1.39 0.88 The rapid decrease in the percentage of the short, immature hypermetropic eye as the child develops is strikingly shown in this table, as is also the irregular yielding of its structure as shown in the increase of astigmatism. In contrast with these statistics of the eyes of school children of all ages, the same writer has examined 87 children from the kindergarten and first grade of the public schools of New York. This survey, while it shows the existence of refractive errors even at that tender age, indicates that they do not occur in so great a percentage or to so high a de-
19
gree as in later years—thus demonstrating the effect of the school in augmenting such anomalies and the necessity of preventing the same as far as possible by appropriate correcting glasses. In 23 per cent of the same children the refractive error was sufficient to require correcting glasses. Wessels reports some interesting cases of refraction from thousands of children whose refraction he has measured as ophthalmologist to the Philadelphia Bureau of Health. In one family of six children, each had hyperopia of not less than 14 and not above 18D. In a colored family of myopes, the youngest of six had 6D myopia and 2 of astigmatism, again the oldest of eight had 17D of myopia with 3 of astigmatism. The highest myopia occurred in a child of 14 with —2/D.Sph; combined with —4. cylinder. He urges that myopic children should be taught in special classes—as more important even than special classes for the mentally defective. Scott calls attention to the relation of eye-strain to headache and other reflex nervous conditions. He makes a plea for the proper correction of ocular defects which lead to strain, and the evils that result from the growing tendency of state legislatures to permit' this work to be done by incompetent 'persons. He details several interesting cases showing the good effect of correcting glasses in relieving various severe functional anomalies of nervous origin. Bruner calls attention to the influence of errors of refraction, or failure in the power of accommodation, or muscular imbalance or weakness of the extraocular muscles as a cause of various forms of headache. He dwells upon the importance of slight errors as against high errors in the production of symptoms, and that the mere fact of normal vision with or without glasses is not proof in itself that uncorrected error is not present. He lays stress upon the necessity of a cycloplegic in young subjects, and sometimes too in older ones. In this connection it is necessary to bear in mind that a number of different conditions may co-
20
REFRACTION
operate in the production of symptoms and that each and all of these should be investigated and receive attention. Corry and Shanker emphasize, not to say exaggerate, the influence of eyestrain in the causation of local and general symptoms. They find "that not only the symptoms of watering of the eye, itching, redness, blinking, sneezing, intolerance of light, headache, burning feelings in the eyelids, head twitching, pain in the neck, vertigo, neurasthenia, and sexual impotence, etc., are due to eye strain; but also different varieties of conjunctivitides, acute and chronic, follicular conjunctivitis trachomatosum, eczematosum, pterygium, xeroses, keratitis, pannus, symblepharon, corneal opacity, episclentis, iritis, cyclitis, choroiditis, glaucoma, cataract, retinitis, optic neuritis, amblyopia, ptosis, blepharitis, hordeolum, chalazion, trichiasis, en- and ectropion, blepharospasm, dacryocystitis, diplopia, squint, nystagmus, nasal catarrh and its complications, etc., are also directly or indirectly traceable to eye strain.." They agree with Walter of Odessa that trachoma is not a disease sui generis, but expresses the reaction of the conjunctiva to various irritants, which irritant is, in their opinion, nearly always eye strain from refractive error or muscular imbalance. A considerable number of brief histories in support of their contention are appended. Kahn writes a paper intended to give the general practitioner a few helpful hints and rules to judge the success or failure of the glasses prescribed. The practitioner should first of all have a thorough knowledge of the symptoms pi eye strain,—a matter very generally neglected, in medical colleges. He insists upon the, advantage of spectacles ^yei-, eyeglasses, and upon the importance .of'.por.recting astigmatism. Hk goes,^0 f^'fj.as^o say 1;nat."any lens that (jpesTn.pt s^p^/an as'tigmkt'ic correction' is presumably incorrect." He gives a homely but striking illustration of the different kinds of refractive errors by comparing the eyes to a two-wheeled vehicle,of which the wheels may both
be of the proper size, or both too small or too large, or one larger than the other, or one or both wheels elliptical in shape, in which latter case the long diameter of the ellipses may be parallel, or take any position whatever. He insists upon the value of a cycloplegic in measuring the refraction. H e gives an explanation of the complaints which even properly fitted glasses may occasion when first worn, and the necessity of a little patience in becoming accustomed to the correction. For presbyopes he advises, besides a bifocal combination, a separate pair for prolonged near work. Finally, as the eye is a living, changing organism, and the correcting lens is unchangeable and stationary, he insists upon the necessity of repeated examinations, which are not to be regarded as a confession of unsuccessful previous refractions. Hartshorne emphasizes the close relations between the motor and sensory nervous supply of the ocular mechanism and the sympathetic system, and that ocular malfunction is a definite and frequent source of irritation of the sympathetic system resulting in symptoms of distant organic disorder. Koster calls attention to the persistence of accommodation in certain elderly persons until unusually late in life, associated with asthenopia. He warns, however, that certain conditions such as senile myosis and incipient cataract may simulate accommodative power. He describes 4 typical cases in persons in the fifties and sixties who appeared to possess 3, 4, or 5D. of accommodation. He has no explanation to offer but thinks that the condition cannot be explained by von Helmholtz's hypothesis. ACCOMMODATION.—Kagoshima found
the amplitude' of accommodation among young Japanese to be about th Fulkerson advocates close cooperation between the dentist and the ophthalmologist. The Roentgen ray, he thinks, should be resorted to more
DIGEST OF THE
often in errors of refraction which correcting glasses do not relieve. The absence of cavities in the teeth is not of itself a sufficient criterion that there may not be an impacted molar or blind abscess that irritates just enough to interfere with normal accommodation. He reports in some detail a half dozen cases in which the symptoms of accommodative asthenopia were present, and which were not permanently relieved until abnormal dental conditions, as shown upon the skiagram (such as
LITERATURE
21
blind abscesses, etc.), had proper treatment. PRESBYOPIC
LENS.—Hill
received observes
that the ordinary bifocal lens is of np use to the presbyope who uses a head mirror or head light. He accordingly advises that the segment 12 mm. in width by 24 in height be added to the center of the distance correction—an arrangement which offers all the advantages of the presbyopic glass plus ability to see at a distance by simply turning the head to one side.
OCULAR MOVEMENTS. W I L L WALTER, M.
r
D.
CHICAGO.
This part of the digest gives a review of the literature referring to its subject that has appeared during 1917 to the close of November. After taking up the different departments of the subject it gives a series of important case reports. My conception of an Editor's function in framing a chapter covering his subject and to be used in the year book of literature—is that it shall give the essence of all papers published in all languages so far as possible, and without regard to the editor's own ideas of their value. It is proper to leave this evaluation to the reader, who is thus free to determine for himself. But he should be given enough to enable him to so determine and should be saved unnecessary reading of detail, if the chapter fulfills its mission-. In an occasional instance, however, the paper is but a review or does not disclose added experience, and in such cases only the title is given, although this plan has to be followed sometimes when the paper is not available for abstract.—(W. W.) SUMMARY OF PROGRESS.—Some points in physiology have had free discussion during the year 1917, notably: (1) Binocular single vision and the function of the oblique muscles. (2) Some new developments in the study of nystagmus have been forthcoming, and the trend is away from the ocular and in favor of the aural origin of this malady. (3) There is an increase in the proportion of paralysis cases of all types and some interesting deductions from them. (4) The correction of annoying abducens paralysis by transplantation of outer bands of the vertically acting recti, thus converting them to abverting functions, has received considerable mention. (5) Reports of effects of war wounds upon ocular movements are beginning to show in the literature.
ANATOMY
AND
PHYSIOLOGY.—Hop-
kins states that, from many dissections of cranial nerves in domestic animals, he is convinced that the accepted de-
scriptions of the motor nerves are incorrect, in attributing two sources of nerve supply to the muscle retractor oculi found in lower animals. It is innervated exclusively by branches from the abducens. H e reviews quite exhaustively the literature on the subject and quotes many authors. His dissections were upon the horse, ox, sheep, pig, dog, cat, and rabbit, and were done under a binocular microscope. He traces the nerves from their superficial origin in the brain to their respective muscles. Dodge has made a contribution on Visual Motor Function which is of interest from the psycho-physiologic side. Roelofs paper on the function of trochlear muscles is not available for abstract. Stahli has reviewed the advance in knowledge of the relationship of ocular movements and the ear. H e speaks of the newer study as "Labyrinthine Ophthalmostatics." In rotation nystagmus the ear is responsible
Crawford has addressed a questionnaire to 90 eye specialists of this country asking their practice as to the use of cycloplegics in refraction. A large majority considered such to be necessary, though there was some divergence as to the proportion of cases in which it need be employed. Homatropin and atropin were the drugs used with very few exceptions. In insisting upon the need of cycloplegics in refraction work, Clarke states that in the absence of a cycloplegic a different result can be obtained at every examination, as it is impossible to determine accurately the degree and axis of a weak cylinder. In proof of this he has carefully determined the refraction of many young patients before and after paralysis of the accommodation : in not a single case did the two agree. He maintains that inaccurate refraction which leaves a slight, but different error from that which was originally present, may cause eyestrain which had not been present before, because the ciliary muscle is now able to correct the new resulting error when it could not deal with the original larger one. CHANGE IN REFRACTION.—Risley
re-
ports a case in which the refraction, from having been hyperopic astigmatism, developed into myopia of —4 and —2.25 respectively in the two eyes, with vision 6/15 and 6/60, following increased tension with numerous exacerbations; and final almost sudden subsidence of the hypertension, in an aged woman subject to arthritis deformans. The change in the refraction was accompanied by obvious thinning of the anterior ciliary region and a groove like formation surrounding the cornea just back of the limbus with tension normal in both eyes. There
were no demonstrable changes in the crystalline lens to account for the increased refraction. MYOPIA.—To cure myopia, Bacchi advocates progressive pressure in the antero-posterior direction by means of the apparatus of Roger d'Ansan with a view to shortening and widening the globe. He reports favorable results following a few sittings. Among various phases of myopia brought to light in Masuda's statistics, the most remarkable is that in 20 per cent the myopia was found to be hereditary. Macular changes appear earlier and are usually of a more severe character in women than in men. Illustrations of various macular changes are appended. The vision with equal errors of refraction, and in spite of early and full correction, is apt to be lower in women than in men. Harriet Gage summarizes a study of myopia, including myopic astigmatism, from the Massachusetts Charitable Eye and Ear Infirmary during 1915. Of 1,524 eyes the refraction was below 3D in 56 per cent; 20 per cent were between 3 and 6D, and 20 per cent were cases of high myopia (from 6 to 15D). Only 2^2 per cent showed very high myopia, above 15D. Of 1,696 myopic eyes 54 per cent showed no astigmatism ; 36 per cent presented compound myopic astigmatism, and 10 per cent simple. The same paper deals also with the age, sex, visual acuity, including the sociologic as well as medical aspects of such patients, and should be consulted in the original. Muirhead opposes the doctrine that the action of the external muscles tends to raise the intraocular tension and to cause lengthening of the globe. He believes that the opposite is the case, in that the action of the muscles tends to
18
REFRACTION
cause an antero-posterior flattening. When the recti are divided, the eyeball moves forward, showing that it is held back by the tonicity of the muscles—an impulse not due entirely, he thinks, to the elasticity of the retroorbital contents, but partly to the elastic recoil of the eye itself. Another argument which the author takes up is afforded by the change in the apparent size of objects. According to the usual hypothesis, pressure is greatest when the eyes converge. As the eye must elongate under this pressure the apparent size of the image should enlarge. The author states that it diminishes. The author is greatly opposed to full correction of myopia, holding that persons wearing a full correction are always uncomfortable and suffer from eye-strain. The above is a short resume of some of the theses maintained by the author in his book. The reviewer believes that every one mentioned is inadequately proven and indeed leaves the question where it was. Those who desire to go into the subject from the author's standpoint must be referred to the work itself. In view of the wide prevalence of myopia in Germany (each year about 9,000 recruits in the Germany army are held back on account of eye affections, the great majority of which are myopes belonging especially to the better classes), the military authorities have attempted, immediately after the declaration of war, to perfect the military education of the younger classes by training exercises (among other factors) of distant vision, estimation of distance, etc. In this connection v. Ziegler relates his personal experience in such training. He had the myopes remove their glasses and exercise their distant vision on targets successively smaller in size. At the end of 6 months all were able to recognize the smallest of the targets. Other exercises in different maneuvers in maintaining straight or oblique directions of march, parallel or perpendicular courses, etc., were also practised with success. ASTIGMATISM.—Nordensen remarks that although the question, whether in
a given case the astigmatism should be corrected or not, occurs daily and is important and complex, it has been little debated in ophthalmic literature, and the text-books give only vague directions on the subject. (This may be true in Europe, but there is certainly iio lack of literature upon the subject in America, in which country there is substantial agreement among oculists generally upon the point in question.— Rev.) This writer reviews the rules for and against the correction of astigmatism. In general, he thinks correction is needed only if it increases visual acuity, (i) where such increase is needed, such as may be called for by the individual's occupation or during the period of education in children, (ii) Asthenopia—chiefly of two kinds: ( a ) accommodative asthenopia. He refers this form to the contraction of the pupil which occurs during accommodation and improves definition by cutting off the peripheral rays; this advantage is obtained by some ametropes by excessive accommodation, bringing the p.p. too close and so interfering with sharpness of vision for near work. The patient therefore relaxes the accommodation, the size of the pupil increases, he reverts again to accommodation, and this alteration produces fatigue and strain, (b) Eyelid Asthenopia. This kind of asthenopia is due to strain of the orbicularis muscle, which can be used to correct inverse astigmatism by the pressure it is capable of exerting in a vertical direction upon the globe. As much as 2 or 3D. can be compensated in this way, but the excessive action of the orbicularis leads to fatigue, (c) Dangers to the eye involved by astigmatism, as favoring the development of strabismus or myopia. In nervous affections, such as epilepsy, migraine, headache, etc., the astigmatism should also be corrected. Among the contraindications he includes: the inconvenience of wearing glasses, when, for instance, one eye is normal and the other astigmatic; nonimprovement of visual acuity after the correction has been worn for some time; intolerance of correction, as in elderly patients in whom the principal meridians do not coincide
DIGEST OF THE LITERATURE
with the vertical and horizontal planes, etc., etc. He rejects the view which has been advanced in recent years as a reason for not correcting astigmatism in children that the anomaly may even disappear spontaneously if it is left uncorrected. EFFECTS OF UNCORRECTED REFRACTIVE
ERRORS.—Carhart insists upon the necessity of careful examination of the eyes of school children, particularly those who appear to be deficient in their studies. He summarizes the result of the examination made 20 years ago, of 1,000 school children of various ages in two village schools; not only those suspected of ocular defects but all the children in the classes from kindergarten through high school. The children were largely American born, in whom the errors of refraction are less common and of lower degree than among a foreign-born city population. He found of emmetropia 13 per cent, hypermetropia 36.20 per cent, C. H. astigmatism 44 per cent, myopia 1.40 per cent, C. M. astigmatism 3.50 per cent, mixed astigmatism 1 per cent. The following table shows the percentage by ages of the various errors in the same 1,000 children: 5 to 8 9 to 12 13 to 18 yrs. yrs. yrs. Emmetropia 10.00 16.43 14.33 Hypermetropia .. 53.48 37.27 22.87 C. H. astigmatism 33.48 40.05 58.55 Myopia 0.87 1.85 1.17 C. M. astigmatism 71.74 3.01 5.26 Mixed astigmatism 0.43 1.39 0.88 The rapid decrease in the percentage of the short, immature hypermetropic eye as the child develops is strikingly shown in this table, as is also the irregular yielding of its structure as shown in the increase of astigmatism. In contrast with these statistics of the eyes of school children of all ages, the same writer has examined 87 children from the kindergarten and first grade of the public schools of New York. This survey, while it shows the existence of refractive errors even at that tender age, indicates that they do not occur in so great a percentage or to so high a de-
19
gree as in later years—thus demonstrating the effect of the school in augmenting such anomalies and the necessity of preventing the same as far as possible by appropriate correcting glasses. In 23 per cent of the same children the refractive error was sufficient to require correcting glasses. Wessels reports some interesting cases of refraction from thousands of children whose refraction he has measured as ophthalmologist to the Philadelphia Bureau of Health. In one family of six children, each had hyperopia of not less than 14 and not above 18D. In a colored family of myopes, the youngest of six had 6D myopia and 2 of astigmatism, again the oldest of eight had 17D of myopia with 3 of astigmatism. The highest myopia occurred in a child of 14 with —2/D.Sph; combined with —4. cylinder. He urges that myopic children should be taught in special classes—as more important even than special classes for the mentally defective. Scott calls attention to the relation of eye-strain to headache and other reflex nervous conditions. He makes a plea for the proper correction of ocular defects which lead to strain, and the evils that result from the growing tendency of state legislatures to permit' this work to be done by incompetent 'persons. He details several interesting cases showing the good effect of correcting glasses in relieving various severe functional anomalies of nervous origin. Bruner calls attention to the influence of errors of refraction, or failure in the power of accommodation, or muscular imbalance or weakness of the extraocular muscles as a cause of various forms of headache. He dwells upon the importance of slight errors as against high errors in the production of symptoms, and that the mere fact of normal vision with or without glasses is not proof in itself that uncorrected error is not present. He lays stress upon the necessity of a cycloplegic in young subjects, and sometimes too in older ones. In this connection it is necessary to bear in mind that a number of different conditions may co-
20
REFRACTION
operate in the production of symptoms and that each and all of these should be investigated and receive attention. Corry and Shanker emphasize, not to say exaggerate, the influence of eyestrain in the causation of local and general symptoms. They find "that not only the symptoms of watering of the eye, itching, redness, blinking, sneezing, intolerance of light, headache, burning feelings in the eyelids, head twitching, pain in the neck, vertigo, neurasthenia, and sexual impotence, etc., are due to eye strain; but also different varieties of conjunctivitides, acute and chronic, follicular conjunctivitis trachomatosum, eczematosum, pterygium, xeroses, keratitis, pannus, symblepharon, corneal opacity, episclentis, iritis, cyclitis, choroiditis, glaucoma, cataract, retinitis, optic neuritis, amblyopia, ptosis, blepharitis, hordeolum, chalazion, trichiasis, en- and ectropion, blepharospasm, dacryocystitis, diplopia, squint, nystagmus, nasal catarrh and its complications, etc., are also directly or indirectly traceable to eye strain.." They agree with Walter of Odessa that trachoma is not a disease sui generis, but expresses the reaction of the conjunctiva to various irritants, which irritant is, in their opinion, nearly always eye strain from refractive error or muscular imbalance. A considerable number of brief histories in support of their contention are appended. Kahn writes a paper intended to give the general practitioner a few helpful hints and rules to judge the success or failure of the glasses prescribed. The practitioner should first of all have a thorough knowledge of the symptoms pi eye strain,—a matter very generally neglected, in medical colleges. He insists upon the, advantage of spectacles ^yei-, eyeglasses, and upon the importance .of'.por.recting astigmatism. Hk goes,^0 f^'fj.as^o say 1;nat."any lens that (jpesTn.pt s^p^/an as'tigmkt'ic correction' is presumably incorrect." He gives a homely but striking illustration of the different kinds of refractive errors by comparing the eyes to a two-wheeled vehicle,of which the wheels may both
be of the proper size, or both too small or too large, or one larger than the other, or one or both wheels elliptical in shape, in which latter case the long diameter of the ellipses may be parallel, or take any position whatever. He insists upon the value of a cycloplegic in measuring the refraction. H e gives an explanation of the complaints which even properly fitted glasses may occasion when first worn, and the necessity of a little patience in becoming accustomed to the correction. For presbyopes he advises, besides a bifocal combination, a separate pair for prolonged near work. Finally, as the eye is a living, changing organism, and the correcting lens is unchangeable and stationary, he insists upon the necessity of repeated examinations, which are not to be regarded as a confession of unsuccessful previous refractions. Hartshorne emphasizes the close relations between the motor and sensory nervous supply of the ocular mechanism and the sympathetic system, and that ocular malfunction is a definite and frequent source of irritation of the sympathetic system resulting in symptoms of distant organic disorder. Koster calls attention to the persistence of accommodation in certain elderly persons until unusually late in life, associated with asthenopia. He warns, however, that certain conditions such as senile myosis and incipient cataract may simulate accommodative power. He describes 4 typical cases in persons in the fifties and sixties who appeared to possess 3, 4, or 5D. of accommodation. He has no explanation to offer but thinks that the condition cannot be explained by von Helmholtz's hypothesis. ACCOMMODATION.—Kagoshima found
the amplitude' of accommodation among young Japanese to be about th Fulkerson advocates close cooperation between the dentist and the ophthalmologist. The Roentgen ray, he thinks, should be resorted to more
DIGEST OF THE
often in errors of refraction which correcting glasses do not relieve. The absence of cavities in the teeth is not of itself a sufficient criterion that there may not be an impacted molar or blind abscess that irritates just enough to interfere with normal accommodation. He reports in some detail a half dozen cases in which the symptoms of accommodative asthenopia were present, and which were not permanently relieved until abnormal dental conditions, as shown upon the skiagram (such as
LITERATURE
21
blind abscesses, etc.), had proper treatment. PRESBYOPIC
LENS.—Hill
received observes
that the ordinary bifocal lens is of np use to the presbyope who uses a head mirror or head light. He accordingly advises that the segment 12 mm. in width by 24 in height be added to the center of the distance correction—an arrangement which offers all the advantages of the presbyopic glass plus ability to see at a distance by simply turning the head to one side.
OCULAR MOVEMENTS. W I L L WALTER, M.
r
D.
CHICAGO.
This part of the digest gives a review of the literature referring to its subject that has appeared during 1917 to the close of November. After taking up the different departments of the subject it gives a series of important case reports. My conception of an Editor's function in framing a chapter covering his subject and to be used in the year book of literature—is that it shall give the essence of all papers published in all languages so far as possible, and without regard to the editor's own ideas of their value. It is proper to leave this evaluation to the reader, who is thus free to determine for himself. But he should be given enough to enable him to so determine and should be saved unnecessary reading of detail, if the chapter fulfills its mission-. In an occasional instance, however, the paper is but a review or does not disclose added experience, and in such cases only the title is given, although this plan has to be followed sometimes when the paper is not available for abstract.—(W. W.) SUMMARY OF PROGRESS.—Some points in physiology have had free discussion during the year 1917, notably: (1) Binocular single vision and the function of the oblique muscles. (2) Some new developments in the study of nystagmus have been forthcoming, and the trend is away from the ocular and in favor of the aural origin of this malady. (3) There is an increase in the proportion of paralysis cases of all types and some interesting deductions from them. (4) The correction of annoying abducens paralysis by transplantation of outer bands of the vertically acting recti, thus converting them to abverting functions, has received considerable mention. (5) Reports of effects of war wounds upon ocular movements are beginning to show in the literature.
ANATOMY
AND
PHYSIOLOGY.—Hop-
kins states that, from many dissections of cranial nerves in domestic animals, he is convinced that the accepted de-
scriptions of the motor nerves are incorrect, in attributing two sources of nerve supply to the muscle retractor oculi found in lower animals. It is innervated exclusively by branches from the abducens. H e reviews quite exhaustively the literature on the subject and quotes many authors. His dissections were upon the horse, ox, sheep, pig, dog, cat, and rabbit, and were done under a binocular microscope. He traces the nerves from their superficial origin in the brain to their respective muscles. Dodge has made a contribution on Visual Motor Function which is of interest from the psycho-physiologic side. Roelofs paper on the function of trochlear muscles is not available for abstract. Stahli has reviewed the advance in knowledge of the relationship of ocular movements and the ear. H e speaks of the newer study as "Labyrinthine Ophthalmostatics." In rotation nystagmus the ear is responsible