B M 31T 737 hi LIFI^ARY I UNIVERSITY OF I CAIIFCHINIA y FUCK THE OPTOMETIIIC LltKAOY MONROE JEROME HIRSCH n^S THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA (;i\T.N Wnil I.OVK TO THE OPTOMETRY LIBRARY BY MONROE ]. HIRSCH, O.D., Ph.D. Optometrical Courses of Study Ocular Accommodation by Charles Sheard, A. B., A. M., Ph. D. Issued by Department of Education American Optometric Association Box 1042, Hartford, Conn. Tf'!jurn'\nYnFTHE Ofl AKGEii a «n'i-«L or optometry il:in w. j;:i n:nfin\ nun. iAiaAUiatS7,C/\LIF. OPTcr.-:~TRV BIOGRAPHJCAL SKETCH Charles Sheard, A. B., A. M., Ph, D. Charles Sheard was born in Dolgeville, New York, May 27th, 1883, and was the first born of the Rev. Dr. Charles and Frances Emily Sheard. During his boyhood days he lived in Richfield Springs, Cape Vincent and Clayton, in the State of New York. His elementary education was finished in the schools of Canton, New York; in 1899 he was graduated from the Canton High School. He received the baccalaureate degrees from St. Lawrence University in 1903. .After teaching in the public schools for two years, he entered Dartmouth College as an assistant in physics, where he remained until 1907, receiving at that time the master of arts degree. In the fall of that year he was appointed an instructor in physics at the Ohio State University and in 1910 was appointed assistant professor in the same institution. The year 191 2 was spent at Princeton University, from which institution he was sent out with the highest scholastic degree granted by universities, the degree of doctor of philosophy, having presented original theses along the modern elec- tronic theory of matter. In 1914 he played an important part in the establishment of the work in Applied Optics at the Ohio State University and became in that year the first director and professor of .Applied Optics. These years spent at the Ohio University were productive of much research work and many a page of writing. The period of the world war found him physically incapacitated but he served in a civilian capacity in optical work as well as carrying out his duties as an instructor and as a clinician at the University. In 1919 the subject of this sketch became a member of the Research Division of the American Optical Company, filling the newly created position of Physiological Opticist. In this field of labor his time is wholly spent, both in writing and in experimental work. His published volumes, some of which are now out of print but which are now in the process of being re-written, include a treatise of over five hundred pages on Physiological Optics, which first appeared as a portion of the thirteenth volume of the American Encyclopedia of Ophthalmology in 1919, a brochure on Dynamic Ocular Tests in 1917 and within the past few months a volume entitled Dynamic Skiametry and other Methods of Testing Accommo- dation and Convergence. .Amongst the chief of his papers along visual optical lines have been a series of articles on Mathematical Studies in Optics and a later group of papers treating upon Accommodation and included under the general heading of Dynamic Skiametry. His researches have carried him into the fields of the electron theory of matter, electric waves, physical optics and physiological optics; his papers have appeared in the Optical Journal, the Keystone Magazine of Optometry, the Ophthalmic Record, the Physical Reciew, the Philosophical Magazine, the Ohio Journal of Science, the fi ellsworth and the Journal of Ophthalmology, Otology and Laryngology. At the present time he is the editor of the newly founded Journal of Physiological Optics published by the Research Division of the American Optical Company. As a lecturer along optical lines he is well-known to the readers of these pages. He has in every word and act endeavored to promote the best interests of the practices of ocular refraction. Course No. 14 Copyright 1920, by Department of Education, American Optometric Association Optometrical Courses of Study arranged by The Department of Education American Optometric Association Edited by William S. Todd, Vice President of A. O. A., and Chairman of Department of Education Ocular Accommodation by CHARLES SHEARD, A. B., A. M., Ph. D., Physiological Opticist, The American Optical Company; for- merly Professor and Director of Applied Optics, the Ohio State University; Author of Physiological Optics, Dynamic Ocular Tests, Dynamic Skiametry, and A. O. A. Course on Static and Dynamic Skiametry, as well as numerous researches and papers dealing with visual optics. Other courses are in preparation and will be issued as soon as possible. Write The Department of Education, American Optometric Association, P. O. Box 1042, Hartford, Conn., for full particulars and list of courses. Education Department William S. Todd, Chairman, Hartford, Conn. Harry J. Covelle, Bangor Me., Ernest H. Kiekenapp, Lake Benton, Minn. Foreword by the Editor This course of Dr. Sheard's on "Ocular Accommodation" is much longer than was originally intended but it was felt by author and editor that it would be a mistake to shorten it. Students who have not procured Dr. Sheard's previous course on "Static and Dynamic Skiametry," issued by this Department, will do well to order it. Any problem pertaining to the lesson not clear to the student will be answered if a stamped, addressed envelope accompanies the request. W. S. Todd, Editor. Course No. 14 Page 1 OCULAR ACCOMMODATION Foreword by the Author When we recall the amount of attention which has been devoted to refractive errors and their correction it is surprising that the study of accommodative anomalies has received com- paratively little attention from students of and practitioners upon the eye. Yet those who deal week in and week out with the problems of refraction must realize and appreciate the fact that these anomalies very frequently arise and often occasion trouble and uncertainties as to the proper procedure to be followed. Possibly one of the reasons why the importance of accommodative anomalies has not been more thoroughly appre- ciated lies in the fact that there is considerable vagueness and lack of clarity in our notions of what is meant by normal accom- modation and a lack of knowledge of the simple tests which may be easily and quickly made to determine the amplitude of accommodation. Probably nothing is as difficult in ocular work as the establishment of standards, such as those of normal visual acuity, amplitudes of accommodation to be normally (;'. e. on the average) expected at various ages, normal duction powers at distance, ample reserve convergence at the reading point and so forth. Hence, it is in general only possible to determine when any given accommodative amptitude should be classed as subnormal or supernormal after we have set the limits of normal accommodative action. And the same remarks are as applicable to convergence as to accommodation. The real significance of tonic muscular imbalances, /'. e. the tests made at twenty or more feet, duction tests at distance, physiologic exophoria, accommodative conver- gence and fusion convergence, together with a determination ot the real demands upon convergence, the amount supplied and the reserves at the close working point are unknown to many practitioners. Let it be stated then in these introductory remarks that the law of supply and demand is as applicable to human eyes as to business. A small drain is of insignificance when the reserve is large, but a normal demand may be taxing if the reserves are low. To illustrate very simply, the expendi- ture of one dollar out of ten leaves a good reserve, while the spending of three out of five dollars approximates the danger line and invites financial inefficiency. So in accommodation or convergence. An accommodative demand of 3 diopters with 5 diopters in reserve is readily met, whereas an accommodative demand of 3 diopters with a reserve of 2 diopters otten entails fatigue and borders on inefrtciencv. .And a'j;ain, a convergence Course No. 14 Page 2 demand of loA with a prism reserve of 25A may signify a con- dition of ocular convergence which can be comfortably met, whereas a demand of loA with but 6A of reserve doubtless means periods, either longer or shorter, of difficulty in securing the act of binocular single vision. Because of the rather limited space at our disposal and be- cause of the importance of accommodation in visual optics, we shall confine our attention wholly to the one topic. And even then we cannot hope to more than brush the surface. We are now laboring upon a rather exhaustive treatise on Ocular Accommodation and some day hope to have it finished and to follow it with a companion volume on Ocular Convergence. The writer recommends that the reader become thoroughly conversant with the excellent course (No. 3 in the Optometrical Courses of Study) by Dr. W. B. Needles. He will find an excellent presentation of many fundamental facts upon the sub- ject of ocular muscles in general. The essay which follows deals with the function of accommodation only. Course No. 14 Page 3 Chapter I. — The Mechanism of Accommodation We shall discuss in some detail various phases and phe- nomena of accommodation and methods of testing the power and amplitude of accommodation -and the significances of the methods and the findings in various ocular conditions. The eye is the most wonderful of all optical instruments in that it possesses the inherent ability, if normal, through the third nerve innervation actuating the ciliary muscles, to change its focus from infinity to its near point in order to throw upon the retina a clear, sharp image of the object viewed. The emmetropic eye, fixing an object at infinity or, in practice, at twenty feet (which involves an error of about one-sixth of a diopter, which is practically negligible) is in a static condition. The word static is to be taken in its broadest sense since experi- mentation has shown fairly conclusively that a normal eve fixing a distant point is in a passive condition under the influence of a slight contractility of the ciliary muscle. Such a statement as this means, in other words, that the normal eye, dissociated from its mate and under the guidance of the will, definitely re- garding an object at twenty or more feet away, is very slightly hyperopic. This may be due to the fact that the maior aniount ot^ distant seeing is done within a radius of thirty feet or less. When, however, the refractive condition of the eve is changed in accordance with the distance at which the object is to" be viewed so as to secure effective focusing of the image upon the retina, accornmodation is involved and the ciliary Ts in a con- tractile condition and the crystalline lens changes shape under Its action. The eye is then in a dynamic condition. Evidentlv then the static refraction of an eye'is that of the whole eve when accommodation is at rest, while the dynamic refraction is that derived from accommodation; hence the total refracting power of an eye is the sum of the two. It is agreed by all that a change from the static to the dynamic is accomplished by changes in curvature of the crys- talline lens. The classic experiments of Cramer, Purkinje, Helmholtz, Tscherning, and others have conclusively shown that an alteration in curvature, confined almost entirely to the anterior surface of the lens, takes place during accommodation. These and other investigators showed that the catoptric images formed by reflection from the surfaces of the crystalline under- went changes bf)th as to position and size when accommodation was brought into play. It is presumably a correct statement of the condition of our knowledge relative to accommodation when it is asserted that the scientific world is certain only of the seat of the accom- modative changes which are dynamically brought about through the ciliary muscle. Several theories have been advanced as to how these changes take place. The two pre-eminent theories Course No. 14 Page 4 are those of Helmholtz and of Tscherning. According to Helmholtz, the crystalline lens, when in a state of rest, is flat- tened to its minimum curvature by the constant traction of the ligament. The natural condition of the ligament is, then, according to this theory, one of tension. During accommoda- tion, Mueller's ring (consisting of the circular fibres) and the ciliary muscle, which is firmly attached to the sclero-corneal border, contract and draw forward the ciliary processes as well as the periphery of the choroid with which the suspensory lig- ament is connected. The latter then relaxes its tension on the anterior capsule and the lens, by reason of its elasticity, bulges outward toward the cornea and so becomes more convex. The theory ot Tscherning is based upon his experiments (see Tschern- ing s Physiologic Optics) which show that the lens of the eye during accommodation has a shape that cannot be accounted for by previous theories. While the central part of the lens is more convex, the peripheral part is very much flattened. Accom- modation is therefore eflected by a dynamic distortion of the lens, giving to the anterior surface a curve approximating to a hyperboloid of revolution. Tscherning, therefore, supposes that the increase in curvature at the central portion of the anterior surtace of the crystalline lens and the considerable flattening at the periphery are obtained, not by relaxation, but by a direct traction of the ligament on the periphery of the lens. He supposes contraction of the ciliary muscle on itself so that the posterior extremity of the ciliary body is advanced and the anterior is receded; this contraction causes a pressure on the vitreous and on the posterior surface of the lens simultaneously with the tension exerted through the ligament on the front sur- face of the lens. The theory of Helmholtz is at present more generally accepted than that of Tscherning, but the views of this latter experimenter seem to account in a more satisfactory manner for the distinct sense of effort which results in presbyopia, accommodation for the near point and sustained accommoda- tion. Bowman's Muscle and its Function — Tilting of the Crystalline Lens A portion of the ciliary body is composed of muscular fibres laid down in flat bundles forming a sort of plexus and known as the ciliary muscle. The fibres composing this muscle may be classified as (i) meridional, (2) radiating and (3) circular. This first set of muscle fibres, which run parallel with the merid- ians of the eye, were discovered by Bowman. This muscle — the so-called "tensor of the choroid" — bears the name of Bow- man. The circular, sphincter or annular fibres are usually referred to as the muscle of Mueller; they form a sphincter ring concentric with the ecjuator of the lens. The most authori- tative opinions upon the functions of these two muscles indicate that the Bowman's muscle is the active agency in keeping the Course No. 14 Page 5 crystalline lens in its correct position in its bed in the anterior part of the vitreous, while, on the other hand, the Mueller muscle, by its contraction, is the active agent in effecting a change in the refractive power of the lens equally in all meridians, the elasticity of the lens being the passive agent. In the progress of the development of the eye, the passive position assumed by the lens in its development may not be correct, hence the need for some active or readjusting agent. This function is doubtless fulfilled by the muscle of Bowman, which, under the guidance of retinal sensations (since the center of the macula is the center of fixation), comes to the aid of this readjustment. It may also happen that a corneal astigmatism may be, in part or in whole, offset by a lenticular condition or tilting of the lens brought about by this muscle acting as the active agent in producing a lenticular astigmatism at right angles to the corneal astigmatism for the purpose of neutralizing it. It can be mathematically shown that when a spherical lens is rotated about any diameter there will be produced by this obliquity of the spherical lens a slightly stronger sphere com- bined with a cylinder whose axis corresponds to the axis of rotation. The formulae for the cylindrical effects of oblique sphericals as usually given are of a complex form, (see for instance their development in A. S. Percival's Optics) but the simple relations which follow in the succeeding sentence may be found in Laurance's General and Practical Optics. If F represents the focal length of the lens and Fi and Fi indicate the effective focal lengths of the meridians of greatest and least power, while "tf" represents the angle of tilt ot the lens, then it can be shown that (i) Fi = F3 cos- a (,) p^^F(3-sin^i) Thus, for example, if the crystalline lens has a power of 16.66 diopters in situ., and it should be tilted about an axis, horizontal and at right angles to the antero-posterior axis of the ocular system, by an angular amount of 10 degrees, calculations show that F equals 6 cm., Fi equals 5-9j8 cm. and Fj equals 5.758 cm. Approximately then, Di (the dioptric value of F,) equals 17.36 diopters and Dj equals 16.82 diopters, which are equivalent as a sphero-cylinder to +16.82 D. S.C+-5 cyl. axis 180 (prac- tically). We have, then, by this tilting of the crystalline lens by an angular amount of 10 degrees an increased spherical power of about 0.16 (one-sixth) diopter coupled with a half diopter cylinder axis horizontal. And again, if this same crystalline of 16.66 D is tilted or rotated 20 degrees about a horizontal axis there will result the following approximately accurate sphero-cylindrical combination, to wit: +17.33 D. S. C + 2.65 cyl. ax. 180, thus showing an increase of spherical Course No. 14 Page 6 power of practically +0.6 D coupled with a cylindrical effect of about +2.75 D, The Function of Mueller's Muscle and of the Iris The contraction ot Mueller's muscle is for the purpose of increasing the refractive power of the crystalline lens equally in all its meridians in the interests ol improvement of vision. If the eye is ametrcpic this muscle will respond under the subject's desire for sharper vision it such action will improve matters. The hyperope, looking at infinity, will accommodate in the interests ot bringing the images in focus upon the retina where possible. This means a reduction in the size of the diffusion circles with consequent improvement in sharpness of images and is accomplished, without doubt, by two factors, the first of which is the chief one, namely: (a) change of lens shape under ciliary action and (b) reduction in pupillary area, since the act of accommodation is always normally accompanied by convergence (which may, however, be suppressed or made non-effective by fusion divergence) and pupillary contraction. It seems likely, therefore, that a hyperope of 1 D, for example, does not necessarily constantly use 2 D of ciliary innervation to cause 2 D of lens change in order to correct his ametropia at distance, since he is aided in his fundamental desire for sharpness and clearness of vision by the normally accompanying contrac- tion of the pupil. This assistance furnished by the contracted pupil may permit the hyperope to see clearly by means of an accommodative effort of slightly lesser amount than his error. The writer has made observations upon a considerable number of cases of hyperopia of from i D. to 3 D. error as to the size of the pupils before wearing corrections and some weeks thereafter, the examinations being made under as nearly identical conditions as possible, and has come to the conclusion that a relief of the ciliary from overtaxation is accompanied by a small but perceptible increase in the size of the pupil. Such an in- crease in the size of the pupil, even though it may be small, produces a corresponding increase in the size of the diffusion circles, and since the visual acuity decreases with increase in the size of pupillary area we have another factor other than the relaxation of excessive ciliary action to consider in the pre- scribing of convex lenses in hyperopia. A lens correction which may slightly blur distant vision may in a little time prove satisfactory because of ciliary relief and because of reduced visual acuity on account of pupillary change. The converse of this proposition seems to be equally true, for myopes cannot accommodate beyond their far-points, for a use of their accommodation would only render them more myopic. Myopes, as a general rule, have rather large pupils. When properly corrected, such persons do not accommodate at infinitv, but see at distance normallv and do accommodate Course No. 14 Page 7 between the far and near points. Under, therefore, the produc- tion of normal accommodative action the pupils will be slightly- constricted, in general, in distance seeing as compared with their initial conditions without correcting lenses; this condition of affairs will cause a slight decrease in the sizes of the diffusion circles and hence add to the clarity of vision. Is it not then pos- sible that this is an important factor in the determination of the proper myopic correction and that it gives us an added reason for the under-correction of myopia in generaP The writer takes occasion to quote the following from an article by C. F. Prentice on " The Iris, as Diaphragm and Photo- stat : — "The aperture ot the diaphragm must, therefore, have a definite and specific diameter for every optical instrument if we are to secure maximum definition and illumination without aberration. The proper diaphragm is, therefore, one of the most important and indispensable parts of every compound dioptric system. The human eye is such a system and is pro- vided with its diaphragm — the iris. In the eye, which is a dynamic apparatus given to variations of power, a fixed diameter of pupil would fail to theoretically fulfill the requirements. When the eye is in a state of accommodation, it becomes a stronger refracting system and therefore needs a smaller aperture of diaphragm, hence the pupil contracts." Yet Helmholtz says: "Von Graefe observed in an eye from which he had re- moved the iris by operation that the normal range of accommo- dation was still present." He concludes: "The iris, therefore, does not play an important role in accommodation." So far as the above noted measurements are concerned, such a con- clusion may be quite correct, yet if construed in its broadest sense it discountenances the value of the iris as a diaphragm entirely." It is nevertheless universally admitted that the iris does act independently of and simultaneously with accommodation. Bonders, in his well known treatise on refraction, says: "Move- ments of the iris are nevertheless associated with accommo- dation; they are governed by the same nerves as the latter, so that, until the mechanism of accommodation is better under- stood, a direct relation between them may not be looked upon as improbable." When the iris acts independently of the accommo- dation it acts as a photostat, regulating the volume ot light incident upon the retina. There must exist, as Prentice points out, a subtle and synchronous balance between retinal perception, uveal stimulus and iritic response. A simple experiment will illustrate in part the main ideas involved in these remarks: If an emmetrope places a i D convex lens before his eye, the normal 20-foot line becomes indistinct with an approximate reduction in acuity to 6 '9. If the lens is now covered with a fine pin-hole disk, normal acute- ness of vision will be re-established. If the actual myopic eye Course No. 14 Page 8 does, under proper correction of its refractive error, have thereby re-established proper pupillary size and sphincter action in accompaniment with accommodation and it we can apply by analogy the reasoning from the above optical experiment with artificial myopia and reduced artificial pupil, we can appreciate the influence which the size of the pupil may have in subjective findings. This is likewise probably one of the reasons why the retinoscopic findings representing, if properly made along the visual axial line, the actual refractive error may not agree ;';/ toto with the subjective findings made when the eye views an illuminated chart at distance and its pupil has its effect upon the visual acuity findings. This subject, the writer believes, is worthy of a series of careful investigations. The active agent in producing changes in the refractive power of the crystalline lens is the Mueller muscle and the passive agent is the condition or elasticity of the lens. In the condition of emmetropia, therefore, no accommodative action is demanded at infinity and images of distant objects are definitely focused upon the retina. An object viewed monocularly at thirteen inches demands normally 3 D. of innervation and 3 D. of resultant lenticular change. Binocularly, no accommodation and no convergence are normally demanded at infinity (twenty feet); at thirteen inches 3 D. of resultant lenticular change in refractivity in each eye are demanded together with an amount of convergence partially and, in fact, largely furnished through the association between the brain centers controlling the ciliary muscle and convergence, together with the assistance afforded by fusional convergence, such that the fixation and accommo- dative points are one and the same and harmony exists between these correlated functions. In hyperopia or hyperopic astig- matism there is a call for activity on the part of the ciliary muscle for both near and distant seeing. In hyperopia the accommodation, unassociated with convergence, must effect an increase of the refractive power of the lens such as will render the image of the object of fixation sharp and clear. But the necessity for the exercise of accommodation tor distant vision is commonly said to disturb the relations between accommodation and convergence with the usual exhibition, upon test, of eso- phoria. In hyperopic astigmatism it is the function ot the Mueller muscle to put the circle of least confusion in the focal interval on the macula. In myopia or myopic astigmatism there is no demand upon the ciliary muscle to do the work when the object of fixation is in the distance. In simple myopia, no accommodation is demanded until the object is brought inside of the patient's far-point. In myopic astigmatism the accom- modative muscles will be brought into play only when the eyes are used in near vision and for the purpose ot placing the focal interval on the macula. This work of the ciliary muscle in improving vision in the near when there is a low degree of myopia is abnormal work, however, even though it is a lesser Course No. 14 Page 9 amount than is demanded in emmetropia. There is, therefore, normally associated in such myopic cases a condition of exophoria. Origin of Anomalies of Accommodation Accommodation is a function ot the ciliary muscle and of the crystalline. The anomalies of accommodation must, there- fore, find their origin in changes and alterations of one or the other of these two factors or of both of them. The diminution of elasticity, to which the crystalline is subject from early childhood on, is the cause of the gradual decrease of the ampli- tude of accommodation and of its total annihilation toward the age of seventy-fiv'e years. If the crystalline becomes rigid from any other cause than senility the effect upon the accommo- dation will be the same. It appears, however, from ophthalmic literature that cases of this kind are rare. Probably in all cases the lens becomes inelastic when it becomes opaque but the changes in structure which produce cataract are accompanied by visual disturbances of such a pronounced character as to cause the diminution in the amplitude of accommodation to vanish into the background as of secondary importance._ It may occasionally happen that the crystalline is separated from its attachment with the suspensory ligament, the zone of Zinn being ruptured in part, producing a subluxation but still per- mitting the lens to occupy the pupillary space. Such a rupture would cause the lens to assume its most convex form and bring the refraction of the eye to a maximum and hence abolish accom- modation. Changes in the dynamic refraction of the eye due to crystal- line changes are less frequent than those resulting from irregu- larities in the operation of the ciliary muscle. We have, there- fore, to differentiate between and to consider spasm, weakening, paresis and paralysis of the ciliary muscle. Some Anatomical and Physiological Facts Relative to the Accommodative Apparatus of the Eye In entering into the presentation of what we have to say upon the topic of the anomalies of accommodation we beg the reader's indulgence while we quote the foUovying paragraphs recalling a few anatomical and physiological facts relative to the accommodative mechanism of the eye. These paragraphs are taken from Landolt's " The Refraction a7jd Accommodation oj the Eyey "The innervation of Brueck's, or of the ciliary, muscle is furnished, as Henson and Voelkers have demonstrated, by the branches of the ciliary ganglion. As they also innervate the iris, and since the movements of this diaphragm are intimately associated with those of accommodation, and since, moreover, the physiology of the ciliary ganglion has scarcely been studied except With reference to the pupillary movements, we will re- Course No. 14 Page 10 capitulate, in a few words, the action of this ganglion upon the iris. The ciliary ganglion sends to the muscle of accommodation and to the iridian diaphragm some fifteen nerve branches, the short ciliary nerves. They perforate the sclerotic in the vicinity of the optic nerve. . . . The afferent branches of the ciliary ganglion arise from three sources: (i) From the common motor oculi (motor root); (2) from the trigeminus, through the intermediation of the naso-cilaris (sensory root); (3) from the great sympathetic (vegetative root). The first of these roots appears to hold under its sole dependence the working of the accommodative muscle (Trautvetter) and of the sphincter of the iris. H. Mayo's experiments have . . indubitably proved that the irritation of this nerve produces a contraction of the pupil. Pathology demonstrates, too, that paralysis of accommodation, as well as the mydriasis which often accompanies it, is due to lesions of the third pair or of the motor root which it gives to the ciliary ganglion. The vegetative root, emanating from the great intercranial sympathetic, controls the dilator of the pupillary orifice (Petit, Budge, and Waller). It was long ago established that the experimental or pathological irritation of the great sympathetic, in the neck, provokes mydria- sis, and that the section or paralysis of the same nerve entails the preponderance of the pupillary sphincter. As to the root furnished by the trigeminus it very probably contains only sensory fibres. "The contraction of the ciliary muscle and that of the sphincter of the pupil are almost always simultaneously exerted, while relaxation of the accommodation is usually accompanied by dilation of the pupil. These two acts are not, however, indissolubly associated with each other. We have only to recall the fact that the pupil contracts and dilates under the influence of variations in illumination, without the accommoda- tion undergoing any change. The reflex movement ot the iris remains intact, not only when the accommodation is abolished entirely by the rigidity of the crystalline, but also in many cases of paralysis of the ciliary muscle. Inversely, immobility of the pupil, under the influence of light as well as under that of accommodation, has been observed when the ciliary muscle worked normally. "Changes in the accommodation are, therefore, generally, though not always, accompanied by modifications in the diameter and mobility of the pupil. Spasm of accommodation coincides with myosis and paralysis with mydriasis. In these two condi- tions the pupil presents a diminution of contractility or even complete immobility under the accommodative impulsion. Nevertheless, the iris reacts, in a certain degree, to variations of illumination unless there be complete paralysis ot the ciliary fibres of the third pair. In ataxia, the contrary is observable. The pupils, contracted under the influence of the preponderant tonicity of the sphincter, which is no longer compensated by the Course No. 14 Page 11 action of the dilator fibres, cease to respond to luminous excita- tion but still contract under the influence of accommodation. "The capital symptom of an anomaly of accommodation is the change in position of the punctum proximum or of the punctum remotum, as well as the visual disturbances resulting from it. "Non-artificial spasm of accommodation, /'. e .^ that which is not provoked by myoptics, brings the punctum remotum nearer, without altering the position of the punctum proximum. Paresis of the accommodation causes recession of the punctum proxi- mum, without influencing the punctum remotum. Hence both affections reduce the amplitude of accommodation, the spasm at its farther extremity and paresis at its nearer. "Now accommodation is in inverse ratio to age and, although this relation is not absolute and mathematical, it nevertheless admits of less latitude than most physiological laws. Bonders' table corresponds, with almost surprising accuracy, to reality; so that, whenever the amplitude of accommodaton is less than that required by Bonders' law, there is reason to seek some pathological cause of its restriction." The Theory Underlying the Determination of the Amplitude of Accommodation The amplitude of accomniodation is, as we have seen, the increase in the refractive power that the eye can assume by means of the contraction of its ciliary muscle. The theory of the determination of the amplitude of accommodation as laid down by Bonders and Landolt in the early days of ophthal- mological and optometric development demands that the re- fraction, /), of the eye which it attains under the maximum curvature of the crystalline lens be known in addition to the refraction, r, of the eye when at rest. The difl^erence between the two is the amplitude of accommodation, a. This is mathe- matically expressed as a = p — r The static refraction, 7% i. e.^ its minimum refraction, is corre- lated with the punctum remotum R by the equation R So, in turn, the maximum refraction of the eye, or that which it possesses when atlapted to the nearest point or punctum prox- imum P, is the inverse of this distance P, or I P = — Course No. 14 Page 12 Acccirding to our classic methods, therefore, the amplitude of accommodation depends for its value upon the accurate deter- mination of (i) the static condition of the eye and (2) its near point. We shall, a little later, point out some factors which limit our accuracy in the determinations of either of these quantities. This is, then, the classic method of theoretically and practically determining the amplitude of accommodation. A knowledge of the patient's static refraction and of his near point has been generally accepted as giving a satisfactory determination of the patient's total and available accommoda- tion. We shall point out in some ot the succeeding paragraphs that the finding of the near point by any of the methods com- monly in vogue may lead to very faulty conclusions as to the total available accommodation when the patient is engaged in near work at the usual reading and working distance. The question of the ability of the ciliary muscle and the crystalline lens to function normally in all cases is not settled by a deter- mination of the near point either monocularly or binocularly. Assuming tor the present that the far and near-points can be accurately located by some method and that these deter- minations give what the classical theory and method say they do, we know that when the eye is totally relaxed it is in a condition of static or minimum refraction and is adjusted for its far-point and that when it is in its maximum dynamic condition it is adjusted for its near-point. If the far-point, R, is 100 cm. and the near-point, P, is 10 cm., then R — P = 90 cms.; this is also the range of accommodation. The amplitude (from the equa- tion a = p — r) would be practically loD — iD = 9D. Theoreti- cally, however, this is not accurate if the near point is deter- mined by means of lenses inserted at the usual distance from the eye; nor again, does the lens, equivalent dioptrically to 100 cms. focus, contribute exactly i D. ot lenticular power it placed other than in contact with the eye. This is an impossibility. To illustrate: if the distance of the punctum remotum from the myopic eye is 125 mms., then the correcting lens placed 15 millimeters in front of the cornea will need to have a tocal length of 125 — 15=110 mms., which corresponds to 9 D. Hence a concave 9 D. lens corrects a myopia of 8 D. The same reason- ing holds in hyperopia; for if the punctum remotum should be determined as lying 1 1 1 mms. behind the refracting plane of the eye there is a hyperopia of 9 D. If the correcting lens is placed 15 mms. before the eye, such a correcting lens must have a focal length of Iii-fi5 = i2; mms. focal length or a refractive power of 8 D. If then the near-point of an emme- tropic eye is at 10 cms., this is dioptrically equivalent to to D. and we can say that the dynamic refraction of the eye must have developed 10 D. of lenticular change. If, however, we should represent the accommodative power in terms of the equivalent amount of concave lens which it can overcome, these lenses being situated, for example, at 15 mms. from the cornea, it is apparent in this case that the amplitude of accommodation Course No. 14 Page 13 1000 would be expressed as = 8.8 D. practically. This ex- 100+15 plains in part why various tests for determining amplitudes of accommodation by near-point and concave lens methods vary and why the concave lens methods always indicate lesser values. When a hyperope or myope is corrected for distance we generally say that there is need of 3 D. of accommodation when reading at 2>2 cms. Theoretical calculations (similar to those given in Laurance, Visual Optics, pages 274-275) show that a hyperope ot 5 D., wearing his distance correction, must accommo- date about 3.38 p. when reading at 13 inches, while a myope of 5 D., corrected tor distance, need use only 2.38 D. of accommo- dation. If such is the case and we test for the amplitude of accommodation by any near-point or concave lens method, it is apparent that the patient under test, wearing distance corrections and therefore supposedly rendered artificially emme- tropic, would show different near points or overcome different amounts of concave lens power although each might inherently possess the same amplitude of accommodation, barring, of course, such factors as age and so forth. Such results as these indicate, as the above calculations show, that cases of hyperopia need stronger lenses for near work, and cases of myopia tull distance corrections. The writer does not find in any literature known to him any researches in which the amplitudes of accom- modation for hyperopes and myopes of fairly high and equal amounts, with ages and other ocular conditions on a par, are recorded. All results for a common age period are usually averaged. This is a problem worthy of investigation because of its bearing upon the strengths of the lenses to be prescribed. If the hyperope, when statically corrected, must needs develop something approximating 10 per cent, more accommodation at 23 cms. than is ordinarily assumed to be demanded and if the myope, when statically corrected, need develop about the same percentage less, these conditions would have an important bearing on a good many phases of ocular refraction. It would, tor example, give a rational explanation for the frequent abnormal esophoric condition at near points as compared with infinity tests in hyperopes and the exophoria ordinarily associated with myopia. The small number of cases in my possession, in which the refractive error is fairly high and not complicated with any appreciable astigmia and in which all the necessary data are available, indicates that the myopes show, on an average, some- thing approximating 15 per cent, greater amplitude of accom- modation. It is not common to find hyperopes of twenty years of age, tor example, showing in excess of '^.'^ to 9 D. amplitude when using concave lenses with No. 2 Jaeger type (V' = .62 D.) at the thirteen inch reading point as the basis of the test; but myopes of about the same age quite commonly show 10 and frequently 1 1 D. under the same method of testing. Course No. 14 Page 14 Chapter II. — The Determination of the Far-Point The Far-point and the Influence of Various Factors Upon Its Determination by Subjective Methods ^^^ Theoretically the far-point is easily determined through a determination of the distance correction for the ametropia present. Such a statement of necessity raises the question as to the accuracy of the various methods of static retraction. The static methods are of two general classes: (a) subjective and (b) objective. The subjective tests must of necessity be based extensively upon visual acuity tests, while the objective methods are largely, if not entirely at the present time, those peculiar to retinoscopy. Subjectively, then, the situation of the punctum rernotum is determined by means of the distinctness of the retinal image. The astronomical researches of Hooke and the physiological investigations of Helmholtz, Snellen and Javal have given us normal visual acuity standard letters which are arranged so as to be seen under an angle of 5 minutes, while the lines which form the letters and most of the intervals which separate them are seen under an angle of i minute. It is well known, however, that some of the letters are more easily read than others on the same line; hence an operator is safe only in saying that a patient's visual acuity is "such and such an amount according to his chart." In order to remedy this defect and introduce an international standard the split ring of Landolt has been proposed, and in many respects this seems more desirable than our older Snellen letters. A method for the expression of the degrees of acuteness of vision which can be used in all languages and which aims to give an official international standard of acuity was adopted by the International Ophthalmological Congress of 1909. The test-type thus officially adopted is the invention of E. Landolt and is known as the broken ring test. The following are the six general principles laid down by the Congress of 1909 relative to the essential features underlying the expression of the visual acuity: (i) The test is based upon the "minimum separabile" or the capacity to perceive an interruption; (2) the test is to be made by means of a black ring on a white ground, the ring to be broken at one place for a space equal to the width ot the limb of the ring, which is, in turn, one-fifth of its diameter; (3) the visual acuteness is to be expressed in relation to the smallest angle under which this can be deciphered; that is, to the maximum distance at which this can be done; (4) the visual angle of one minute is the standard of comparison; (5) the mode of expression is to be either in decimals or as a fraction (V = d/D)and (6) the eye is to be tested only at a distance from the test-object. Edward Jackson {Ophtha'hnic Record, March, Course No. 14 Page 15 1916) in an article on "Cards for Sight Testing in Schools," points out some of the features of superiority of the international test of visual acuity. He mentions: (i) It is a fixed or con- stant standard. This is impossible with test letters. (2) It is unlearnable. With the broken ring it is only needful to con- ceal the card and turn it and a new test is obtained. (3) The test is more exact and easier to understand because it is made at a variable distance. In the ordinary Snellen letter plan there is no provision for intermediate grades, between, say, 20/20 and 20/30. But with the test card of broken rings of a single size the acuteness of vision is ascertained by noting the distance at which they can be seen and this distance can be noted to any fraction of a meter or foot that seems desirable. (4) The apparatus required for the test is much simpler, less expensive and more convenient to handle than the cards of test letters. In general, these same points of advantage are applicable to office practice as well as to sight testing in schools. The question of the adoption of a standard test on the part of all practicing retractionists is a vital one and is worthy of considera- tion by readers of these paragraphs. Many believe that the charts of test letters in common use in consulting room prac- tice are admirably adapted to the subjective determination of errors of refraction but that, as a test for visual acuity, they give the poorest and most inexact standard. The Far-point and the Influence of Various Factors Upon Its Determination by Objective Methods The skiascopic and ophthalmometric findings constitute the results by objective methods which are of value in refractive work. The ophthalmoscope as a refractive instrument has long since been superseded by other objective devices: the ophthalmometric findings and their diagnostic value have been discussed elsewhere by Ryer. In the writer's opinion it is best to make an ophthalmoscopic examination as one of the first steps in all ocular investigations, chiefly for the purpose of determining upon the existence or non-existence of pathological conditions. When the instrument is used in such a manner that the anterior focus of the observed eye approximately coincides with the optical center of the lens turned up in the lens battery, with relaxation of the observer's accomm.odation, due allowance being made for the observer's ametropia if such exists, a very quick and approximate estimate of the refractive condi- tion may be obtained by an experienced operator. Under the above conditions the minimum of concave and the maximum of convex lens needed in order to see the veins and arteries at a point some little distance from the optic disc and approach- ing the macula from the superior and inferior regions will afford an approximate estimate of refractive conditions. This, with ex- Course No. 14 Page 16 perience, is of considerable assistance in the subsequent saving of time in other objective determinations. The fundamental principle involved in static retinoscopy is conjugacy of foci; that is to say, a point upon the retina under observation and the nodal point of the observer's eye when neutralization of shadow motion occurs should bear the relations of object and image points similar to those exhibited by any convex lens system. It is not desirable at this point to go fully into the theory and practice of skiametry, but rather to simply call attention to the fact that under ideal conditions, with proper relaxation of the patient's accommodation, proper positions of visual axis with respect to the line of observation and examination and accurate centering of optic media, perfect neutralization of skiametric shadow motion should be possible; this method should therefore afford a means, par excellence, of determining objectively, and hence, scientifically accurately, the patient's far point. But these ideal conditions rarely exist: there are certain possibilities of error in skiascopic tests which give rise to disagreements between such determinations and those made under subjective tests. We have in another treatise {Physiological Optics) discussed certain'factors which may influence determinations upon far-points based upon visual acuity tests; we shall briefly enumerate and discuss at this point some of the reasons why static skiametric tests as carried out in the customary manner in our consulting rooms may be inaccurate or incorrect in the sense that such findings may rather materially disagree with subjective findings. The element of infallibility, it is always to be remembered, does not attach itself to any one single method or test, hence a comparison of all ocular data and a modification in the light of the evidence furnished by all tests upon the various ocular functions is demanded in the final binocular fittings. Ciliary Relaxation' — -Fixation Definite But Passive (i) If the patient vaguely looks into space, without the assistance of some definite and partially visable fixation point, his gaze is more than likely uncertain in direction as well as position in space. Theoretically — and practically if ideal conditions could be obtained — an indefinite fixation into space is desirable. As a matter of fact, such indefinite fixation into non-illuminated space is a most difficult procedure, with the result that the patient, stimulated by the natural desire to see, will grope for some object or point sufficiently luminous to be seen and only too often may be actually detected, by virtue ot the erratic action of shadows, fixing a near object, very often the operator himself. This objection, per se, may be overcome by using the illuminated one hundred foot letter or letters at twenty or more feet; if these are not visible the form of the chart as a whole or the frame in which it lies will generally be so in Course No. 14 Page 17 the initial examination and it" not, it is a matter of no conse- quence since the insertion of lenses, which approximate in part tne necessary correction, will make such fixation and vision possible. To insure this fixation during the process of objective refraction the patient may be asked to read the letters and tell whether they are more or less distinct as various lens changes are made by the operator and so forth. The great criterion in static methods is ciliary relaxation. Hence monocular fixa- tion must be definite (at a point twenty or more feet away), but passive. Various schemes have been advocated in order to assure such relaxation. One such device used by the writer, and, as far as known, original with him, consists in turning up in the lens battery of the optometer or introducing into the trial frame sufficient lens power to considerably overcorrect and cause opposite retinoscopic motion to that initially discovered when only working distance lenses are inserted. The procedure is to then slowly reduce lenticular power until the maximum plus or minimum minus just before reversal of shadow occurs is reached. The writer is satisfied that higher degrees of hyperopia will often be disclosed under such modus operandi. Another method suggested, but which the writer does not advocate, is the putting of a strong fogging lens together with a four or five diopter prism base in over the eye not being tested. The theory is that the fogging lens will blur to such an extent as to eliminate the action ot this eye when testing its mate, while the prism, base in, will relax the ciliary through the relation of accommodation to convergence. It is very doubtful if such a theory is correct; to the best of our knowledge inhibition of innervation to the interni may be accomplished through inhibition of the third nerve innervation to the ciliary, but the process does not appear to be reversible. Retinal Sensitiveness to Light (2) Retinae unduly sensitive to light may cause, under the influence of the light thrown into the patient's eyes, a tem- porary irritation that will produce a spasm of the ciliary. Such reflex actions may be induced to relax by dimming the source of light used in retinoscopic work. Very often satisfactory results can be obtained by the use of the self-luminous instrument in which the luminosity can be controlled through a resistance. Cases arise in which lacrymation is excessive and photophobia pronounced and in which the patient winces and squints when the light is thrown into the eyes. Under such conditions one must make his findings ad interim — waiting a few moments, then quickly noting the direction of shadow and making the necessary lens changes until neutralization has been obtained. Or the subjective findings may very properly constitute the sole Course No. 14 Page 18 findings under such conditions; frequently ciliary relaxation is much more complete under fogging methods. Irregular and Peripheral Refraction (3) The corneal curvatures and those of other refractive surfaces may not be truly spherical and they may not be prop- erly centered. As a result irregular refraction may be suffi- ciently marked as to cause inability to accurately locate the point of retinoscopic neutralization. The "visual zone" is the portion to which attention should be directed; irregularities, neutralization of shadows and even reversals of motion may occur in the peripheral regions in fairly large pupils due to aberration and other effects. These are at times confusing and annoying. Very often thin, colorless ribbons, approaching in form the band peculiar to astigmatism, may arise which are due to irregularities in various dioptric surfaces or media; gen- erally these fail to prove out in subjective testings. Macular vs. Non-Macular Refraction (4) One of the chief sources of error and discrepancy in retinoscopic work is the fact that most skiascopists do not test the part of the retina which is the conjugate of the point pas- sively fixed: that is, the refraction is not determined along the visual axis. When using the subjective method the patient views in turn each of the letters: an image ot these letters, one at a time, is formed on the fovea centralis. In our ordinary methods of skiametry we produce a spot of light (image of our light source) upon the patient's retina at a point which is several degrees from the fovea centralis. We may at best, under average conditions, be conducting our investigations along the optic axis, although this is uncertain since the position of the optic axis with respect to the visual axis is a variable quantity de- pending upon the ametropia present, for the two axes may coincide in certain degrees of myopia and we should then be working along neither optic nor visual axes. If, as is quite commonly done, the patient's gaze as to his right eye is directed over the operator's right shoulder and over his left for the left eye, the image from the operator's mirror may fall at or near the optic disc, as is evidenced by the character of the reflexes obtained at times. Certainly optic discs, as to contour, peripheral elevation or depression and so forth, are as unlike as the faces of their owners. And, furthermore, one cannot assume a uniformly curved or spherical retinal surface; the fovea is known to be a slight de- pression in the macular area; hence objective findings may differ considerably when the light spot upon the retina falls at or remote from the fovea. Our knowledge of the fact that Course No. 14 Page 19 one millimeter change in axial depth of an eye corresponds practically to a change of three diopters in refractive power would mdicate the marked effects which slight differences in level between two retinal points made conjugate, in turn, to the observer's nodal point may produce. The vital point is, then, that the skiascopic findings are not ordinarily made along the visual axis and hence many irregularities, such as certain cases of scissor movement for example, may arise and disagreements between objective and subjective methods result because of lack of proper scientific precautions in knowing the conditions under which each is carried out. John C. Eberhardt has devised a simple and ingenious method of testing very close to the fovea centralis and the writer is pleased to say from experience that he has found it most serviceable. The "macular reflectoscope" as constructed by the inventor consists of a stand placed, say forty inches from the patient and carries two mirrors. The device is diagrammatically shown as a horizontal cross-sectional cut in Figure i. -e ^ — K3 A 1) R O Figure i. — Diagrammatic Scheme for the Use of the Macular Reflectoscope. The macular reflectoscope is represented at D and consists of two parallel, plane mirrors, L and A^ so placed before the eye of the person being examined as 10 enable an iluiminated eighty or one hundred foot letter {B in the figure) to be seen or at least fixed upon by the eye. A, in its primary position by virtue of the double reflection of light by the mirrors L and N placed at an angle of about forty-five degrees with the line of sight. The double mirror device causes a lateral shifting of the letter or letters viewed; a single ray of light from the illuminated letter (5) to the macula (A/) or fovea centralis is shown as B-L-N-M. The operator, 0, with retinoscope at /?, may then proceed to the skiametric refraction of the eye in a direction approximating the direct line of sight. By this device the possibility of incor- rect findings will be reduced to a minimum if, by the use of mirrors as described, we test close to the visual axis. Course No. 14 Page 20 The writer uses the macular reflectoscope attached to the rod of his phoro-optometer by means of a special sleeve sliding along the rod ordinarily attached to the instrument and em- ployed for carrying the reading and near muscle-test cards. This sleeve carries a screw permitting of its rigid clamping; through a socket at the side of this movable sleeve runs the rod carrying the mirrors. This gives practically every motion as to angle and height of mirrors desired and allows of its ready Figure 2. — Showing the Macular Refltctoscope in Use. attachment to or removal from the optometer or can be swung by means of the rod out of the way when not in use. It can likewise be placed as near to or as far from the patient as desired (up to twenty-six inches approximately), so that when +1.5 D. S. is used as a working distance lens the observer's retinoscope is stationed just back of one of the mirrors. This or any other scheme similar to the macular reflectoscope can also be used without ;trouble when a chart over the patient's head and a mirror at ten or so feet away are used in the testing room. Figure 1 shows a simple arrangement used by the writer for demonstrating the method. Figure 3 is a reproduced photo- graph of a macular reflectoscope as attached to the rod of the phoro-optometer and shows how this valuable device can be used in conjunction with such an instrument. Course No. 14 Page 21 Figure 3. — Macular Reflectoscope Attached to the Phoro-optometer. j ^ A very splendid instrument involving these and other refinements has been devised by Dr. Armbruster of Denver, Colorado. In passing it may be stated that dynamic skiametry, whether or not it is accepted as being wholly correct in other respects in theory and practice, obviates nearly all of the difficulties which have been rehearsed in the preceding paragraphs. For if a small card of printed matter, set in No. 2 or 3 Jaeger type, is attached by means ot a clip to the edge of the retinoscope, it will furnish a series of very definite fixation letters which likewise demand accommodative action on the part of the patient reading them, and the visual line of both eyes as examined in turn will lie very close to the observational line. Likewise, constricted pupils will eliminate peripherial and other similar slight irregularities obtained under static methods and the accommodation, through our instructions to our patients to read the card, will be whipped into action to its maximum capac- ity, hence totally eliminating the question of relaxation of accommodation as understood in the static sense. Further- more, the eyes will assume their positions o^ torsional equilibrium; hence the axes of the correcting cylinders may be found some- what shifted in position from those found under static monocular methods. But dynamic skiametry introduces the perplexing problem of the correlation between convergence and the accom- modation and the question as to the validity of the findings, under some possible modifications, for distant as well as near visual use or as a reading correction only. Course No. 14 Page 22 Chapter III. — The Determination of the Near- point and of the AmpUtude of Accommodation The Near-point and the Influence of Various Factors Upon Its Determination Thus far we have discussed some of the methods and useful means of determining the far-point through various objective and subjective methods of finding a suitable lenticular correc- tion which would render infinity and the retina of the eye under test conjugate points We have paid particular attention to pointing out some of the discrepancies which may arise between subjective and objective findings in monocular tests, but have not discussed the broader and more vital question of the proper co-ordination of the eyes in binocular vision. We do have, however, both objective and subjective methods for the deter- mination of the manifest error of an eye and by means of simple mathematical expressions, taking into account the distance of the lenticular correction from the cornea, are able to calculate the manifest or apparent punctum remotum. For those who desire there remain in addition those determinations upon the absolute refractive conditions which are made through the use of cycloplegics in which, presumably, the absolute punctum remotum can be determined. It, therefore, seems scientifically possible to make accurate determinations as to the location of the apparent and of the absolute far-points. We are not as fortunate when we come to the determination of the near-point and hence to the ultimate determination of the amplitude of accommodation, which involves the difference between the static and dynamic refraction of the eye. But we have an objective method for determining the position of the punctum proximum as well as various test objects and subjective methods of finding its location. All have inherent errors and defects. For as Tscherning says: "The determination of the near-point is not very certain, since its position depends upon an effort of the patient, the strength of which may vary from day to day." And Landolt, writing in that classic volume entitled The Re- fraction and Accommodation of the Eye^ (which parenthetically the present writer wishes some scholarly practitioner would revise and some enterprising publisher reprint) says: "If, in practice, we seek the punctum proximum, we wish to know the maximum refraction that an eye can assume under the impulse of the will and not under the influence of a cause foreign to the organism. This will being manifested especially in the interest of near vision, the person examined should always be permitted to be himself master of his desire to see distinctly and the judge as to the degree in which he succeeds in so doing. In other words, we are dependent in the determination of the accommodation upon the patient's good nature and intelligence; a fact which Course No. 14 Page 23 often deprives the examination of the desired accuracy. It is for this reason, too, that there exists no objective method (properly so called) of obtaining the amplitude of accommodation. The maximum effort of accommodation is hard to obtain from the patient unless we give him an object of fixation. But by so doing we return to the subjective methods. ... In order to know whether the object is at the punctum proximum we must have recourse to the clearness of the visual impression." We do possess, however, the objective method devised in recent years by the writer; still the objection that Landolt raises is applicable. There are two principles or methods of procedure in common use, which are in theory essentially identical, for determining the dynamic refraction. We either seek the situation of the near point and measure its distance from the eye and take the inverse of this quantity to represent the total dynamic refraction or else we determine upon that lens whose refractive power equals that of the eye at its maximum of accommodation. I. Determination of the Situation of the Near-point To obtain the near-point, commonly used test-objects con- sist of small printed character or fine type, or groups of small black dots upon a white ground or black threads on a white background stretched across a frame constituting an instrument usually referred to as the wire optometer. The commonest method in vogue is to employ about No. 2 Jaeger type (V= .5 D.) and to approach this toward the eye, its mate being covered, until the nearest point is reached at which it can still be seen or read, or in other words until it commences to get indistinct. A measurement of this distance from the cornea of the eye is commonly taken as the punctum proximum. In a case of emmetropia this distance, when reduced to diopters, gives the amplitude of accommodation. This method in ametropic cases gives only the apparent or available and not the true amplitude. Likewise, it may not be available in presbyopic conditions, since the near-point may have receded so far from the eye that fine print is not readable; in such a case, however, a convex lens may be furnished to assist the patient and bring the near point to a measurable discance, finally deducting the auxiliary lens from the dioptric value found. In ametropia the practitioner will be saved considerable time and trouble, as well as mental arithmetic, in obtaining the true amplitude of accommodation if he supplies the patient with the correction for the refractive error statically determined at infinity first of all, since then presumably the far-point is at infinity or approach- ing it as closely as conditions, both pathological and non-patho- logical, will permit. The eye is then emmetropic or as nearly so as possible and the procedure in determining the amplitude of accommodation is the same as that for emmetropia. The statement relative to the giving of the distance correction Course No. 14 Page 24 when making tests by any method upon the near point or in the determination ot the amplitude of accommodation is worthy of repetition, since the absence of cylindrical corrections, especially if they are of any appreciable value, plays a considerable role and almost invariably leads to incorrect determinations and conclusions. The determination of a correct near-point is not as simple in practice as in theory. For the size of the test or type-object must, in the first place, bear a certain relation to the visual acuteness of the eye under examination. There are persons who possess a good range of accommodation who cannot read fine print at any distance because their visual acuteness is too low; in such cases larger test-objects must be used. And, in the second place, as already pointed out, the punctum proximum may be so far away as to render small test-objects indistinguish- able, even by an eye whose visual acuity is normal. This difficulty is remedied by the giving of a convex lens which in- creases the refraction and hence brings the near-point closer; this arbitrarily added lens must ultimately be subtracted from the refraction corresponding to the near-point of the system to give that of the eye alone. The first objection, i. e., that ot reduced acuity, must, however, be an inherent difficulty in the determination of the accommodative amplitude of such an eye by whatever method tested. In the second case the accommo- dative power, either normally or abnormally depleted, must be assisted in order that the test-object may be seen. The question arises as to whether or not, if different quantities of assistance are offered, the ultimate determinations of the near-points will be in agreement. Let us assume two cases: (a) suppose the lens given to be -|- 10 D. and the point up to which vision remains clear to be 9 cms. and (b) suppose the lens given to be +6 D. and the point up to which vision remains clear to be 14 cms. Each of these cases of a theoretical nature brings out the punctum proximum as one meter distance from the eye. In practice such determinations would involve uncertainties or errors of measure- ment which would be vital, since small distance differences may represent considerable refractive differences; but, assuming such errors excluded, the two determinations inherently involve differences due to the sizes of the retinal images by virtue ot the fact that the same sized object, when placed at 9 cms. and at 14 cms. respectively from the eye, subtend different visual angles at the nodal point of the eye. Hence it is very doubtful whether two such tneoretical cases leading to the same result would, if tested in practice under the conditions named, give equality. My experience, which has been rather limited in making such determinations with wide ranges of lenticular assistance offered, has led me to the conclusion that only approximate agreement is forthcoming. Course No. 14 Page 25 This discussion leads us to the really vital source of error in near-point determinations and that is this: the size of the retinal image of the test-object increases as the test-object is approached to the eye; hence, if a five minute visual angle stand- ard is to hold in near as well as distant testings, a type which fulfills this criterion at 33 centimeters from the eye will, at a lesser distance, give retinal images which are too large and there- fore give inaccurate near-points. Inaccurate accommodative amplitudes from near-point determinations are due, the writer believes, to two factors chiefly: (i) there is a more rapid increase of the visual angle than of the circles of diffusion, hence the person under test is able to read at a point nearer than that at which accommodation is still being proportionately enforced; by this is meant, in other words, that the enlarged retinal images, although diffused, are mentally interpreted and seen when smaller but sharper images are not, and (2) the reduction in the size of the pupil which occurs normally upon the approach of an object to an eye and which in turn lessens the sizes of the circles ot diffusion. Diameters of the diffusion circles will be still further reduced if the pupil changes size, as is the case upon the approach of the test-object to the eye. The size of the circle of diffusion, 2, may be calculated for any sized diameter pupil of exit, />, from d z = p d±a an expression in which a represents the distance of the retina from the pupil and d the distinct image from the retina (see Tscherning, Physiologic Optics^ page 73). If then the quantities d and a remain constant, as would be in the case ir the eye were viewing a given object at a given position, the circles of diffusion will be decreased in area as the diameter of the pupil contracts. It can be seen, therefore, that the factors affecting the readability of fine print at a point close to the eye are varied and that they are rather interdependently and intricately related. The explanations in which we have just indulged afford us reasons as to why, in cases of high hyperopia or high hyperopic astigmia, small objects can be seen better nearer the eye than at some distance from it, thus resembling a condition of myopia. For the high hyperope, far from moving his book away from him, brings it, on the contrary, very close to his eyes — much nearer than^his real punctum proximum — in such a way as to simulate myopia. This hyperope, so to speak, "applies his eyes to the paper"; being unable to obtain distinct retinal images, he obtains as large ones as possible. His circles of diffusion are not an obstacle to him, for, in the first place, their diameter, generally limited by the narrowness of the pupils, increases only in proportion to the square root of the decrease in distance, Course No. 14 Page 26 while the size of the image increases proportionately to this decrease itselt. And, in the second place, there exists in his case (high hyperopia) a singular aptitude for analyzing imperfect retinal images and making out the form of the object in spite of the diffusion circles of which its image is composed. There is still another and important factor affecting the readability of fine print at a point close to the eye and, therefore, the determination of the punctum proximum. We have already mentioned the effect of the increase of the visual angle and hence of the retinal image as a type which fulfills the proper visual acuity standard at thirteen inches is approached toward the eye under test, and we have also discussed the effect of the decrease of pupillary area and of the diffusion circles upon the retinal images. All of these sources of error tend in one direction and that is to indicate a punctum proximum closer to the eye and hence a greater equivalent amplitude of the eye under test than it in reality possesses. There is in addition the effect of closing the lids and thus narrowing the palpebral fissure; this virtually amounts to a restriction in the size of the pupil of an eye which may have already contracted considerably as to the near-point test is being made. This narrowing of the pupillary opening by lid action is particularly potent and active in the case of high astigmats or, in general, for those eyes possessing reasonably large ametropic errors. There will thus result an effective decrease in pupillary size analogous to the effects pro- duced by a stenopaic disc with the consequent reduction in the size of the diffusion circles and the fine type when moved closer and closer to the eye. In astigmatic errors such a lid action would enable accommodation to be exerted to an extent suitable for the horizontal meridian; it is possible, therefore, that this stenopaic slit action will either augment or decrease the apparent distance of the near-point from the eye. If, therefore, one is certain of his cylindrical correction it seems a wise procedure to insert it before the patient's eye before making any near- point determinations, for it can be shown that the sizes of the diffusion focal lines and ellipses vary in size directly as the pupillary aperture and as their respective distances from the retina. The reader will, therefore, appreciate the fact that the writer is not very enthusiastic about the value of near-point determinations as ordinarily made with a tape line and a tew lines of fine test-type. Of course, in the average run of cases it serves well enough in that Nature has been reasonably generous to mankind in general and been sufficiently democratic to give the majority of people at any certain, specified age about the same modicum of accommodation. Hence, after perscribing the distance correction for the specified age as given by the usual "Punctum Proximum — Age" chart, one might pass the case up as accommodatively satisfactory and probably, in the light ot Course No. 14 Page 27 the percentages of persons of all ages who exhibit normal as opposed to subnormal or abnormal accommodative conditions, satisfy the majority of his patients and give them ocular comfort and efficiency if other details in the ocular examination have been carefully determined and regarded. But subnormal and paretic accommodation or premature presbyopia is not as rare as it was thought to be years ago and in some of the really intricate and difficult cases near-point determination will often lead one into error. Some such cases with various determina- tions upon the ocular functions follow in succeeding paragraphs in this chapter. These same objections are in a measure applicable to our ordinary methods of determining the amplitude of accommoda- tion in presbyopia by finding the nearest point at which No. 2 Jaeger type (usually) can be read after an arbitrary amount of convex lens assistance has been given. There must, of course, be ultimately subtracted from the near-point equivalence in diopters the amount of convex lens offered in assistance. We find in like manner the reading far-point and thus determine the range of reading amplitude. But it can be said by way of support of our ordinary methods of ministering to presbyopic conditions that the factors which are so effectual in vitiating near point determinations are not as effective and hence important in such presbyopic determinations since, for one reason, the near point has receded from the eye hence making it impossible to draw the print as close to the eye as can be accomplished by young people. Furthermore, such presbyopic conditions are not due to a fundamental weakening of the ciliary muscles but merely to an increasing hardness or lack of elasticity of the lenticular substance and no efforts, however strong, on the part of the ciliary muscle can increase the curvature of the crystalline lens beyond a certain point. We must differentiate, therefore, between normal and abnormal accommodative changes or between proper and premature presbyopia. Our only objective methods for the determination of presbyopic corrections are dynamic skiametry and the writer's objective method of deter- mining the range and amplitude of accommodation. Certainly extreme accuracy cannot be claimed for either method. We can by its usage, however, determine the accommodative needs of a pair of eyes at any given reading distance, modified pre- sumably by the demands for harmonious correlation between accommodation and convergence. Likewise, the amount of reserve accommodation which should be preserved, ranging from a quarter to a half of the total amount available, varies with practitioners and should, indeed, vary in the light of the determinations which should be made upon the convergence as associated with the accommodation. We are sadly in need of methods as applicable and as scientific in presbyopic cases as those we possess in general ametropic and muscular testings. Course No. 14 Page 28 The writer on Amplitude of Accommodation in the American Encyclopedia of Ophthalmology says: "The near-point is the distance at which an object can be seen distinctly with the greatest curvature of the lens. In practice, fine print, (Jaeger No. I or the corresponding Snellen type) is used to determine the near-point. These tables are brought near to the eye until the print appears blurred. The size of the object and the width of the pupil are important factors to be considered and as the above method deals with a narrow visual field only, not the real near point but a "pseudo" near point is obtained, which, in general, is nearer to the eye than the true punctum proximum." Certainly, then, in the light of all this evidence it is only proper that the practitioner record his results by such methods as "pseudo" near-points and not true near-points and many of the statements in our text-books upon the determination of the near point should be revised in accordance therewith. The position of the near-point may be found by employing some method depending upon Scheiner's experiment The eye, gazing at a small point through two small holes close to- gether in a disc, will see the point fixed as double if the eye is not sharply focused and single if it is. With the least error in focusing two points will be seen instead of one. This and Young's optometer are probably among the best devices for obtaining true near-points, but they are impracticable for use with the average patient and involve a co-operation between patient and practitioner which is difficult of obtainment. In fact, as noted once before, any method of determining near- points or amplitudes of accommodation is dependent upon the will and good nature as well as intelligence of the patient. The most satisfactory subjective tests must involve, after all is said and done, the reading of printed words, some of which should be familiar and some unfamiliar to the person under test. II. Determination of the Near-point by Ascertaining the Lens Whose Refractive Power Equals That of the Eye at its Maximum Accommodation, the Tests Being Made Monocularly at Twenty Feet A simple lens is sufficient to determine the refraction of the eye at the moment of its maximum accommodation. Thus, as Landolt says, "for a person whose punctum proximum is situated at a finite distance, it amounts to the same thing whether he looks at an infinitely distant object through a concave lens" or, without a lens, at an object situated at a distance equal to the focal length of the lens used. A concave lens gives to parallel rays of light the divergence that they would have if they came from the point represented by the focal length of the lens. To see at 16.66 cms. a refractive change of accommodation of 6 D. is demanded of the emmetrope. In order, in turn, Course No. 14 Page 29 to see distinctly at a distance through a concave lens of 6 D. power an excess of positive refraction or an accommodative change amounting to 6 D. is evidently required in order to neutralize the negative 6 D. of the concave lens. Hence, theoretically at least, we need only to seek the strongest con- cave lens (equivalent to the difference between the strongest plus and the strongest minus, or weakest minus and strongest minus, which are dependent upon the ametropia present)"through which an eye still sees distinctly at a long distance and this lens will give the maximum of refraction of which the eye is sus- ceptible." The quoted portion of this last sentence is from Landolt: the italics are due to the writer for the purpose of calling attention to the fact that the indetiniteness of "seeing distinctly at a long distance" and just what should be the standards of test in such methods constitute some of the chief drawbacks to the practicability of employing concave lens for determining amplitudes of accommodation under the conditions specified. Let us consider a few simple cases and then pass on to a further discussion of the merits and demerits of such procedure. For an emmetrope with eye adapted to parallel light, one eye being occluded, the strongest concave glass expresses directly the amplitude of accommodation. An emmetrope seeing dis- tinctly at a distance with a — 8 D. lens before his eye has an amplitude, according to this method of determining it, of 8D. For myopia, the strongest concave lens with which he sees at a distance still gives the position of the punctum proximum and the refraction corresponding to the maximum accommodation. In order to find the amplitude of accommodation, however, the static myopia must be known. The amplitude of accommoda- tion is, therefore, expressible as the difference between the strongest and weakest minus lenses with which distance can be clearly seen. A myope of 2 D., being able to overcome a — 8 D. lens, would have 6 D. of accommodation. A hyperope who sees at a distance with a concave lens also has his punctum proximum at the focus of the latter and under this condition the refraction of his eye is likewise equal to the refractive power of the concave lens that it neutralizes. But a hyperopic eye may be regarded as an insufficiency of refractive power, hence accommodative action must in reality supply this deficit in addition to the concave lens overcome. If the degree of hyper- opia be 1 D. and the concave lens through which distance is still clearly seen —6 D., then the amplitude of accommodation is 8 D. And, again, it may happen that the maximum effort of accommodation does not suffice to wholly neutralize the hyperopia. If the strongest convex lens gives the measure of the static refraction of the eye, the weakest convex lens indicates the maximum refraction obtained with the aid of the accommodation. Hence the difference between the two is the amplitude of accommodation. To recapitulate, then, the Course No. 14 Page 30 strongest concave or weakest convex lens with which an eye can see at a distance gives the refraction of that eye when adapted to its punctum proximum. The sign of the lens must be changed, however, since concave indicates positive and con- vex shows negative refraction. In emmetropia the concave lens expresses directly the amplitude of accommodation. In myopia we must subtract therefrom the value of the lens which corrects the ametropia. And in hyperopia the amplitude of accommoda- tion is given by the algebraic difference between the dioptric value of the strongest concave or weakest convex and that of the maximum correcting, or convex, lens. There are several vital objections to this procedure, however, (i) The visual acuteness is considerably diminished by the use of concave lenses which diminish the size of the retinal images, for it is difficult for experienced observers to judge accurately as to whether their visual acuteness suffers from a lack of clear- ness or from the diminution in the sizes of the images. (2) The term "distinct vision at distance" is very indefinite. If the normal acuity line is taken as a standard, /'. e., when a corrected eye can really develop this acuity, the effect of concave lenses upon the retinal images thereby produced makes it rapidly unreadable. (3) It is difficult to get an eye to put forth its maximum effort of accommodation when looking at a distance. Accommodation is not invited nor encouraged as it is by an object approached progressively to the eye. (4) It is a test upon a function made in a manner which demands that it be brought into play under conditions contrary to those set for it by nature. The minimum accommodative condition of an eye is always demanded and generally obtains when viewing distant objects. It is certainly true that the amplitude of accommodation obtained by this method is less than that furnished (apparently) by a direct determination of the near- point in the manner discussed in previous paragraphs. The reasons are very obvious, for the factors, such as increase in size of retinal images, which are likely to cause a pseudo near- point which is too close to the eye, are exactly reversed in their character, i.e., a. decrease in the size of retinal images for example, when using concave lenses and viewing a distant test-object. It seems not at all improbable that an average of the two ampli- tudes obtained by these two methods will give, in the general run of cases, a fairly true estimate of the real amplitude of accommodation. This "concave-at-distance" method, as we are pleased to call it, however, inaccurate as it may be, is probably a much safer method to pursue than the near point determination by fine print and it affords valuable corroborative evidence in tests made by still another method yet to be discussed. The writer uses this method at times and proceeds in general upon the following basis. First of all the statically determined monocular correction is inserted in the trial frame, one eve is Course No. 14 Page 31 occluded and the other put under test. Incidentally, the writer in private practice uses the phoro-optometer, (carrying the lens battery) which enables him to make rapid changes and complete the tests by this "concave-at-distance" method of determining the amplitude in short order. If the acuity is normal under the correction offered, the writer usually selects the V = 8/io (to V = 6/io) line as a basis for the test-object to afford distinct distant vision, the patient being seated 20 feet from the chart. The procedure is then to find the maximum minus through which these test-objects can be seen in cases of hyperopia and so on as outlined in the preceding paragraphs. Some very interesting observations can often be made during these tests. In some instances the accommodative action is sluggish or non-responsive, requiring time to respond, while in other cases it is very responsive but when once pulled out to its full capacity seems to be unable to withstand the demands for but brief periods of time. We shall have occasion to refer to such conditions under the topic of Subnormal or Difficult Accommodation. Illustrative Case. In cases of paretic or subnormal accom- modation valuable information is often quickly obtained. To illustrate: take the following case: — A girl, aged 8 years, just recovering from measles, is round shouldered and has, when we give her a book to read, a decided tendency to thrust her neck and chin forward; this tendency has apparently devel- oped due to the fact that the mother has tried to induce the child to hold her book away from her face while reading; the child has apparently very logically concluded to come to the book if the book was not allowed to come to her. Subjectively we found O. U.+0.50 D. 8.3+0.50 cyl. ax, 90, giving V + 20 20. Monocularly +1 D. S.^+O-fO cyl. ax. 90 blurred distant vision badly. Through a —.5 D. S. + -5 ax. 90 or through — .5 D.S. alone she was hardly able to see the 50 foot letters or even distinguish relatively small objects in the room. Her total amplitude according to this test is, therefore, 1.5 D. She could not read No. 2 Jaeger type, wearing her distance correc- tion, at 13 inches, but could read it when this type was pulled up to within four or five inches of her eye. This is a beautiful example of pseudo punctum proximum and of the erroneous conclusion to which it would lead a practitioner. Her accommo- dation was, then, approximately 1.5 D.; the accommodative demands may have been innervationally met, but certainly lenticular action did not result, yet it is to be doubted if the necessary innervation at the near-points at which she read was delivered to anything like the full and normal amount. She was presumably possessed of no more refractive changes through accommodative effort at 5 inches than she was at 13 inches, but the decrease ot pupillary size, the closing of the eyelids and the increased size of the retinal images enabled her to read at an abnormally close reading point and not at a normal reading point. Course No. 14 Page 32 We gave her +1.5 D. S.C+0.50 cyl. ax. 90, O. U., to be worn while reading and at near work during the first few days and to be worn as constantly as possible thereafter. She could read No. I Jaeger type readily at 13 inches. She was likewise referred to her family physician to whom a report of her condition was made. Today she is wearing O. U. + - D. S.O+0.50 cyl. ax. 90 and has six or seven diopters of accommodation. Ill Determination of the Near-point and of the Amplitude of Accommodation by Ascertaining the Lens Whose Refractive Power Equals that of the Eye at its Maximum Accommodation, the Test Being Made Monocularly at Thirteen Inches This method is essentially a modification of that discussed in connection with the determination of the punctum proximum and of the amplitude of accommodation by finding the lens whose refractive power equals that of the eye at its maximum of accommodation when the tests are made monocularly with test letters at twenty feet. In the discussion of the aforesaid method it was pointed out that one of the most vital objections to such a procedure lies in the fact that it is a test upon a func- tion made in a manner which demands that it be brought into action under conditions which are not in accord with those under which it normally functions and operates. Accommodative action should be nil at twenty feet; it therefore seems an illogical procedure to test its maximum capacity at a point for which there is normally demanded its absolute suppression. This fundamental and basal principle in all ocular investigations is very clearly and forcibly expressed by Eberhardt in his ''Dynamics and Economics of the Binocular Functions'' when he writes: "One of the inflexible rules which, therefore, must underlie the investigation of any given ocular function is 'that such investigations must be conducted under conditions of activity or quiescence which conform to the phil- osophy of the particular phase of its activity under considera- tion'. " We have previously discussed near-point determina- tions by the use of reading test-types and have pointed out valid objections to placing the dependence in and upon them such as is desirable in all ocular investigations. And here again one of the most valid objections is that normally accommodative demands are not made upon the visual machine at three or four inches from the eyes; all emmetropes, or those who are prac- tically so by nature or by optical assistance, read and do all so-called "near work" at about twelve to fifteen inches. The requirements for comfortable binocular vision imposed by the function of convergence have doubtless been the determining factor in establishing the commonly accepted normal reading point and not the function of accommodation, for it has been Course No. 14 Page 33 conclusively shown (see the research of Landolt and others) that at least one half to possibly two-thirds of the total conver- gence amplitude must be held in reserve if comfortable binocular vision is to ensue. The average pair of eyes (64 mms. pupillarv width) exert approximately 18A of convergence when fixing at the 13 inch point and should have in reserve at least an equal quantity, /. e., 1 5A to 20A. Such positive convergence amplitude, if normal development in youth accrues and if undue demands upon it by virtue of an inharmonious correlation of accommo- dation and convergence are rectified or sufficiently assisted, remains practically constant throughout the usual span of a lifetime. Accommodation, however, decreases with increasing years, not presumably because of weakened innervation or insufficient motor centers, but because of lenticular changes, such as loss of elasticity, which make curvature changes under the action of the ciliary impossible. Or possibly the Mueller's muscle weakens and is less responsive to innervation as increas- ing years creep on. Doubtless both ciliary weakness and lenticular changes are responsible for the diminution. The major portion of all our near work is most advanta- geously done at about thirteen inches. As a result, therefore, the accommodative demands are met with respect to this point. It seems, then, that by far the most logical subjective method would be to investigate the accommodative resources at the ordinary reading point. The method is easily and readily carried out. The test should be made monocularly and in front of each eye as tested should be placed the distance finding, particularly the cylindrical element. The spherical element should be the maximum convex or minimum concave lens which, either alone or in combination with a cylinder as the case may be, aflFords V = 20/20 or as nearly the normal standard as condi- tions will permit. If distant vision can be raised to normal or not less than 8/10, the writer uses the No. 2 Jaeger type (V = o.5 D. S.) as the standard in conducting the test under description. Such test-type being held at thirteen inches, the distance correction being worn, the ciliary must then exert 3 diopters of accommodative action and produce 3 diopters of lenticular action, or 3 diopters refractive change, it acting normally when the eye reads fine print at the distance specified. Minus spheres, ' commencing in general with a — i or —1.5 diopter glass (although this should be regulated by our knowledge of the probable amplitude of accommodation as judged from the age of the patient), are then inserted or turned up in the lens battery in conjunction with the phoro-optometer until the maximum minus lens has been inserted through which No. 2 Jaeger is barely readable. By this method of testing, the operator is furnished data upon the total accommodative ampli- tude as available at the reading point. Advantages and Disadvantages of this Method. Possibly one of the chief disadvantages in the use of concave lenses in the Course No. 14 Page 34 testing of the accommodative resources lies in the reduction in the sizes of the retinal images and hence of the apparent size of the type read. The well-known action of concave lenses is to minimize the size of objects seen through them. Their insertion before an eye demands that the corresponding accom- modative changes on the part of the lens be produced if the object is to be clearly seen, /'. e., the accommodative mechanism must adjust itself to the added divergency caused by the wearing of the concave lens. The simple formula which connects the object and image conjugates and the focal length of a single thin lens is I I I fi U F in which /i represents the image distance, /2 the object distance, and F the focal length of the lens. In the case of a negative or diverging lens the formula reads I I I fi U F If, then,/i is taken as the object distance, namely, at a constant I distance of 13 inches, and — is taken in turn as equivalent to F — iD., —2D. and so forth, a simple calculation will show that fj is respectively —10 inches, —8 inches, —6.66 inches and so on in front of the lens. This demands, therefore, that 4 D., 5 D. and 6 D. respectively of accommodation be exerted to see the object under examination distinctly at the thirteen inch point. But two factors enter: (i) The size of the image produced by the concave lens decreases in the following ratio: Object size Object distance Image size Image distance To illustrate: If the object is one centimeter high, then the following brief table shows the sizes of the images as pro- duced by the lens having the focal length specified; the position of the object is held constant at thirteen inches. Object i cm. High at Thirteem Inches Object Position Image Position Lens Inserted Size of (Inches) 13 (Inches) 13 (Diopters) No lens Image I 13 10 -I D. 10/13 13 13 8 6.66 -2D. -3D- 8/13 62/3/13 Course No. 14 Page 35 Such effects as these would be produced by the concave lenses alone. (2) But these images are affected in their sizes in that they are increased by the action of the accommodative mechanism upon the crystalline lens. The crystalline lens being thickened at the center under the ciliary action and the chief seat of this action lying in the anterior crystalline surface, the eye will have its nodal points changed and its equivalent single nodal point removed further from the retina, with the result that the visual angle will be increased as compared with that which exists when concave lenses are inserted before the eye and no accommodative action occurs. This subject is rather intri- cate and has been treated in part by Bordier. An account of his calculations is to be found in the Encyclopedic francaise d'Ophtalmologie, Volume III. The net result is, therefore, a minimizing of the retinal images and hence of the apparent size of the test-objects: it should be expected then that the determinations upon the amplitude of accommodation as made by concave lenses would be lesser in amount than by near-point measurements. In the state of accommodation, however, which is a temporary myopia ot curvature, the two nodal points will be displaced toward the cornea. For the accommodation necessary at a quarter ot a meter, it can be shown that the relative increase of the retinal image is approx- imately one-fifth of the size which it possesses when in a state ot repose. It is thus seen how the shifting of the nodal point away from the retina compensates in a considerable measure for the reduced sizes of images due to concave glasses when used in the manner under discussion. The reader can refresh his memory upon the conditions which exist when a test-object, such as a line of No. 2 Jaeger type, is read and the amplitude of accommodation determined by finding the punctum proximum, by reference to the paragraphs in which this method was discussed. Let it be briefly stated here, however, that the effects are just the reverse or opposite of those obtained by the concave lens method, since retinal images will be increased in size due to: (a), approach of constant- sized test-object toward the eye; (b), contraction of pupil, and (c), narrowing of palpebral fissure in certain cases. We should, therefore, conclude that the near point methods will all lead to higher values of the accommodative amplitude; while concave lenses, whether used in testing the accommodation at twenty feet or at the reading point, as now under discussion, will lead to much lower values. The writer believes, then, that the results of the two methods should be in general averaged as giving the correct measure of the available accommodation in cases of normal visual acuity and upon the exhibition of a quantum of accommodative action which is regular and easy throughout its whole range and which is comparable to that which should normally be expected of the patient at the age given. Course No. 14 Page 36 Some Simple Illustrations of the Principles Involved in This Method. A few simple illustrations of clinical or office practice involving this method may not be inappropriate. Let us assume a distance correction of +1 D. S. 0+0.50 cyl. ax. 90 affording practically normal vision. The practitioner, then, armed with the information that the visual acuity is normal for distant seeing, hands the patient the reading test-chart, occludes the eye not under test and directs the patient to read the No. 1 Jaeger type when held at thirteen inches, or, better still, inserts the small reading card furnished with the phorometer in the slide provided with such an instrument and sets it at the thirteen or fourteen inch point. The test is then carried on, using minus spheres, until the maximum concave lens is found through which the No. 2 type is just readable or some of the commoner words can be made out. If the practitioner has at his command a phoro-optometer the lenses may be readily changed and by as small steps as seem desirable. It need hardly be said that memory or academic vision must be elim- inated from such a test; hence as the patient reads a portion of a line it is well to "turn in" minus lenses as rapidly as the re- sponse of the person under observation permits until the read- ing becomes sufficiently difficult as to involve rather slow prog- ress in its accomplishment. The accommodation, if strong and active, should respond readily to the demands made upon it up to within possibly three-quarters of its total capacity. To return, then, to our illustrative case, we turn up —2, —3, —3.5, — 4 diopters and so on, giving the ciliary time to respond in each case, until finally, let us say, with a —5 D. S. reading is difficult and with a —6 D. S. the reading of much larger type is impossible. We therefore conclude that the total accommodation available at the thirteen inch reading point as evidenced by this modus operandi is, as a maximum, 9 diopters. This 9 diopters is the sum of the 3 diopters exerted by the accommodative mechan- ism in order to read at thirteen inches and the 6 diopters of additional accommodation as elicited by the concave lenses inserted. If, again, with —2D. S., V = 20/20, these tests upon the accommodative resources are instituted, the patient wearing the distance correction, and it is found that a —3 D. S. meas- ures the maximum reserve at thirteen inches, it may then be concluded that, under the conditions through and by which the tests are made, some 6 diopters of accommodation are available and can be effectually put into operation at the reading point. Reasons for the Insertion of Distance Binocular Findings When Investigating the Accommodative Resources at the Reading Point There are certain very valid and important reasons for the insertion of the findings affording best acuity conditions at dis- tance before the eye under test. By the expression "best acuity Course No. 14 Page 37 conditions at distance" we very naturally refer to the binocular findings which have ministered to the refractive conditions to the full amount of hyperopia possible and given us the minimum findings in myopia. (i) Investigations upon the accommodative resources normally follow (at least such is my practice) after the obtain- ment of static and dynamic retinoscopic findings, subjective testings and the investigations upon the muscular equipoise under static and dynamic conditions. Incidentally it may be stated that in the writer's investigations upon the muscular condition as exhibited at distant and near-points the patient is provided with what, in the writer's judgment, in so far as data at hand can direct him, will constitute the binocular cor- rections. Such binocular corrections consist of the maximum convex and minimum concave lenses affording practically normal acuity when such is. obtainable, although we are quite prone, both from theoretical grounds and from experience, to slightly fog binocularly in young hyperopes and to leave the binocular myopic corrections in cases of reasonable quantities thereof such as to afford not much better than 8/10 vision. In the determination, therefore, of the reserve accommodation at thirteen inches the eye under test is furnished with practically that correction which, unless other tests have indicated or the one under discussion should indicate to the contrary as not adequately meeting all the economic binocular demands, it will ultimately receive. Hence, the tests upon the total accommoda- tive reserve are made under conditions imposed upon them by the optical corrections and assistance which the static refractive errors have demanded and which they may perchance ultimately receive. We have, in other words, primarily determined through our static tests at twenty feet the^efractive assistance which is needed in the interests of the establishment of best or most comfortable visual acuity conditions or the restraint of abnormal ciliary action and so forth and are desirous of knowing whether or not such a correction will fit in with the economic and com- fortable operation of accommodation and convergence at near points and whether or not the new demands or readjustments imposed upon the accommodation are such as to afford an harmonious correlation of functions without imposing condi- tions upon any one function which may cause our final solution as to the needs of a pair of eyes to be inadequate or unbalanced from the functional standpoint. (2) The wearing of the distance correction will furnish the eye with such optical assistance as to insure the practitioner that its manifest punctum remotum will be situated practically at infinity and that, therefore, its accommodative mechanism has been so aided as to permit of its meeting most advantageously the normal demands made upon it as the fixation point is moved from twenty feet to thirteen inches. In other words, when Course No. 14 Page 38 furnished with its full distance correction its range of accommo- dation is not afi^"ected as would be the case if its myopic, hyperopic or more particularly its astigmatic errors had not been, in large measure at least, corrected. This point appears to the writer to be an important one in the modus operandi of this particular method of testing accommodative quanta; eyes when tested either singly or in co-ordination should be as nearly emmetropic as our various tests enable us to render them. (3) The practitioner is relieved from the necessity of making the very simple but apparently, to many, rather confusing arithmetical computation as to the total accommodation avail- able; the total available accommodation is, when the distance findings are worn, represented as the lenticular equivalent of the maximum concave lens inserted plus the three diopters of accommodation demanded by fixation and reading at thirteen inches. If, for example, an eye genuinely myopic 5 diopters were under test with fine print at thirteen inches, it would be impossible for such an eye to read, since the far-point thereof, when uncorrected, would be at eight inches; such a case would therefore demand that at least enough concave lens be inserted to carry the far-point beyond the point of the test in hand. And again, to illustrate the arithmetical calculation just men- tioned, assume that a hyperope of 2 diopters uncorrected, is able to read fine print at thirteen inches through —3 D. S.; the total accommodation is, then, 8 diopters, of which, however, without correction, only 3 diopters is in reserve, since 5 diopters are demanded to supply the requisite 2 diopters accommodation to overcome the hyperopia and furnish the necessary 3 diopters normally demanded at thirteen inches. A myope, on the other hand, of 2 diopters, reading at thirteen inches through the maximum concave lens possible, let us say —3 D. S., has a total accommodative amplitude of 4 diopters only and a reserve of 3 diopters, since an uncorrected myope of 2 diopters exerts but I diopter of accommodation in reading at thirteen inches. It is very questionable, however, as to whether these figures representing the accommodative demands in the interest of overcoming the refractive errors are correct, since it can be demonstrated from calculation upon the effectivity of lenses situated at the usual distances from the eye that the accommo- dation exerted in corrected hyperopia is greater and in corrected myopia is less than would appear from ordinary considerations involving the optical equivalence of linear distances. For calculations show that a hyperope of 5 diopters when corrected must exert some 3.45 diopters while reading at 2>2> cms. and a corrected myope of 5 diopters must accommodate only 2.38 diopters at the same point. All other things being equal, then, a myope and hyperope of equal quantities of error, of the same age, pupillary conditions and so forth, should not presumably show equal quantities of accommodative resources. That is to say, the myope should exhibit greater amplitude of accommo- Course No. 14 Page 39 dation and greater reserve. Of course this result or this condi- tion of affairs may easily be vitiated due to the fact that by non-usage the accommodation may have become inefficient in myopia or, again, non-available through spasm of the accom- modation, ciliary hypertrophy and so on in hyperopia. (4) The practitioner is afforded, when the patient is wearing the binocular distance findings, a ready and safe basis for those modifications which he may desire to incorporate in the prescription that he ultimately gives the patient by reason of the tests upon the accommodative amplitude and reserve and upon the muscular poise at the reading distance. We will illustrate the purport of this remark by the findings in a case which has just left our hands and which caused an interruption in the penning of these sentences. A young man, aged 23 years, came to us wearing O. U. —.25 D. S., as we discovered after finishing our own tests. These glasses he said had been given him for distant use only and that he was admonished to remove them while reading. He complained of that tired feeling, ocular fatigue, sleepiness creeping upon him while reading, and said that, contrary to instructions, he had, in his desire to see what he could do to improve matters, worn his glasses while reading and that they seemed to benefit him for a short time but were soon of no service. Static retinoscopy disclosed an erratic or spasmodic condition, O. U.+0.50 D. S. being apparently the approximate findings. It was found that binocularly V = 2o 20 practically with O. U. + .75 D. S., although slightly blurred. The muscular poise, both at distant and near-points, these lenses being worn, disclosed no conditions of imbalance. The monocular near-point proved to be at about six inches, equivalent therefore to 7 diopters roughly, and the tests with minus lenses disclosed the fact that his total available accommodation, after much coercion, did not exceed 6.5 diopters, the eye being assisted by the +-75 t)- S. Dynamic skiametry evidenced the need of lenticular assistance at the reading point to the extent of O. U. + 1 -5 D. S. In the light of all the evidence furnished we felt justified in prescribing O. U.+ i D. S. to be worn while reading and to be gradually "worked into" for distance as well, when they would presumably adequately meet the ocular demands and afford ocular comfort. Experience has demonstrated that in nine-tenths of such cases, with proper instructions to the patient, such refractive treatment will solve such ocular problems as this. And, by the bye, \ve always take occasion to point out to the patient the trend oi probable experiences to be encountered in the readjustment ot the ocular functions to normal conditions and send the patient away with the statement that we shall expect another visit for inspection not earlier than a week or ten days. He who fails to see to it that his patient returns to him in due time is not wise and he, in turn, who has his patient at his heels the morning after is less wise and has failed to exercise that psychological control which Course No. 14 Page 40 is so essential in all professional practice. But enough of this! The patient asked us as to whether or not he could make any use of his old lenses and we informed him that he might use them with profit for exercise in the rhythmic manner described by Savage. If you have not thoughtfully perused these methods of rhythmic exercise both for the extrinsic and intrinsic muscles, take occasion to look into Savage's Ophthalmic Myology. It is, of course, always to be borne in mind that accommo- dative conditions will, in general, improve under the proper refractive treatment. The constant use of corrective lenses has the effect of maintaining and often of restoring good accom- modative action if it has become depleted owing to non-use. Likewise, excessive accommodation may have been exerted in near work in cases of uncorrected astigma; the proper cylin- drical corrections will relieve this sectional ciliary action and in time produce normal accommodative conditions. And in hyper- opia we may expect normal innervation to be accompanied in general by normal responses in lenticular changes when read- justed ocular conditions obtain. It is just as reasonable to expect such physiologic reactions, especially in the young, in ocular functions as would be looked for in the ultimate normal functionings of the muscles in an arm which, either from non- use or from excessive use, have become abnormal in their responses. The insufficiency does not, therefore, immediately disappear on application of the correcting lenses because the defect has become more or less chronic and hence does not at once respond to the removal of the cause. We should look for results in accommodative changes similar to those experienced in muscular imbalances in which usually we do not find immediately any marked alteration in the imbalance when correcting lenses are applied. The writer believes from his experiences with dynamic skiametry that this system of ocular refraction does, in general, disclose that refraction assistance which may be at the time of examination demanded by the accommodation at near points, due regard in this respect being given to the demands which may be apparently indicated as being made by the accommoda- tive function, but which may in reality be demanded in the interests of the proper correlation of accommodation and fixa- tion at the point of observation. We are, therefore, as a general rule, inclined to take the dynamic findings as a measure of the maximum demands made by a deranged ocular system at the reading point and, with these and other tests as the basis upon which to form our judgment, give such corrections as we believe will adequately aid the ocular functions to re-assume normal conditions, but not such complete corrections as to wholly relieve the various functions involved from any necessity of action in the re-establishment of comfortable and economic conditions. Course No. 14 Page 41 (5) The thirteen inch or thirty-three centimeter point should be ordinarily chosen as the point at which the accommo- dative resources are to be investigated rather than a nearer or more remote point, for the reason that nature has ordained the establishment of a comfortable convergence and a normal distance of distinct vision at about a foot from the eyes. Let us, in passing, compare some of the results obtained upon the amplitudes and ranges of accommodation. One of the most interesting discussions upon this subject is by Alexander Duane, in an article entitled: "The Anomalies of Accommodation Clinical- ly Considered," read before the American Ophthalmological Society in July, 191 5 (see The Keystone Magazine of Optometry^ Volume 10, page 349, 1916). Near-points were determined by measurement from the anterior focus of the eye, /'. ^., from a point 13 mms. in front of the cornea. He says: "The patient whose accommodation we are testing is placed with his back to the light (good, diffuse daylight should be used when possible), and is directed to look sharply at the test-object (a fine black line bisecting a white parallelogram which is mounted on a disc of black velvet). The eye not under examination being covered, the test-object is brought toward the patient along a Prince's rule until the fine line blurs and then is carried back and forth several times, until we ascertain the nearest point at which the line can be seen with perfect distinctness. . . . Repeated tests should be taken and care must be exercised that the results are not vitiated by the patient's inattention or lack of com- prehension of what is expected of him." The average results only for each age mentioned are included in the subjoined table. The table given by Jackson is generally accepted as being as nearly correct as any. Of this table Savage says: "The error, if any, is in the showing of too much ciliary power after the age of thirty years. This table shows the relative or asso- ciated accommodation and is much greater than would be shown if accommodation, unassociated with convergence, were tested with concave lenses." We give these tables side by side and venture to add our own values from several hundred cases (ranging mostly, how- ever, from fifteen to thirty-five years of age) as found by the concave-at-near tests. Course No. 14 Page 42 Amplitudes of Accommodation Jackson (Concave Sheard lenses. (Monocular Accommodation Test Object associated at 13 in.) Bonders Duane with Concave ^ge (Near-point) (Near-poin t) Convergence) Lenses. 10 14 n-s^ 14 15 12 12.6 12 II. 20 10 II. 5 10 9.0 25 8.5 10.5 9 7.5 30 7 8.9 8 (^.^ Z<> 5 7-3 7 5-0 40 4 5-9 S-S 3-75 45 3 3-7 4 .... 50 1 2.0 2.5 .... ^S I 75 1-3 1.25 60 I 00 I.O 0-5 With reference to the values which the writer has tabulated as determined by him to be about average values for the ages specified by the concave lens method with observation at the ordinary reading point, the writer has to say that he has never seen in print any table giving such determinations. It will be noted that they run in general from 1.5 to 2 diopters below the values given in the tables by Jackson and Duane, and are more nearly in agreement (although considerably lower) with those given by Bonders. In the obtainment of these data cases only were recorded in which the visual acuity could be brought to normal or 20/20 at distance, the maximum convex and minimum concave lens power, together with the astigmatic corrections, being worn throughout the tests. It is of interest to note in passing that Thorington lays down, and very properly so, as one of the criteria to be met in determining visual acuities that the astigmia be first corrected by establishing equality of lines in the ordinary astigmatic chart. We ordinarily use No. 2 Jaeger type (V = o.5 B. S.) as the standard test-type in the determination of the accommodative resources at the reading point by means of concave lenses, and the maximum lens added until reading is impossible even under the added impetus and goading of the examiner. W^e have already remarked that in general we have found the amplitudes of accommodation for myopes of a given age greater than those of hyperopes (both being brought up by means of lenticular assistance to normal acuity at twenty feet) for the corresponding period of life, all other factors being as nearly identical as possible. This state- ment probably holds good for those possessed of small errors or in cases in which the refractive errors have been properly Course No. 14 Page 43 cared for in the past. It cannot be in general expected that maximum values of accommodative amplitudes will he obtained in high myopic or hyperopic errors upon their initial correction, tor in one case there has been a subnormal demand upon accom- modation and in the other case there has been an abnormal demand, hence there may be weakness in one case due to non- use and in the other condition weakness due to overstrain of the ciliary muscle, together with abnormal nutritive processes developed in the ciliary body and the lens. It is probable, however, in those refractive conditions which are low in value or which, it high, have been corrected over a period of years that a greater amplitude of accommodation will as a general proposition be developed in myopia as compared with hyperopia. A Case Illustrative of Pseudo Near-points arid the Unre- liability of Conclusions. In some preceding paragraphs atten- tion has been directed to the possibility that the use of the near- point determinations, such as by the reading of fine print, for the determination of the amplitude of accommodation and its range may lead to spurious results. Briefly, in resume, the reasons are: {a) increase of size of retinal image with approach of the constant sized type to the eye, {b) pupiFlary contraction, thus cutting down the sizes of the diffusion or confusion cir- cles and {c) the narrowing of the palpebral fissure, particularly in cases of astigmia. We shall in the succeeding paragraphs present a case which is amongst the most interesting and probably most difficult in ocular refraction. Such cases are difficult for the reason that they demand the best judgment on the part of the practitioner and likewise presume that he is sufficiently versed in the general systemic and symtomatic conditions and after-effects or accom- paniments of certain diseases such as anemia, diphtheria, measles, scarlet fever, neurasthenia, hysteria and so forth, as to be able to intelligently recommend medical attention or co-operation in the case or withhold the same when conditions warrant. While these cases admirably illustrate pseudo near-points and the invalidity of data thereby obtained, and while they further emphasize the necessity of examinations upon the accommoda- tion and correlated functions, they likewise illustrate conditions of subnormal, weakened, pre-presbyopic or depleted accommo- dation. In general, let the writer say in passing, in cases of doubt, where the history, appearance of the patient, symptoms of which complaint is made and all the ocular tests indicate a possible paresis of the accommodation, whether temporary or permanent, or toxemia, medical examination should be recom- mended and insisted upon. We have no patience with the non-medical practitioner who fears to refer a case in the interests of the patient's welfare to his or her family physician or other desired medical specialist lest the case should fail to be referred back for refractive assistance, and, in turn, let me waste paper Course Xo. 14 Page 44 and ink enough to say that we think as little oi the medical practitioner who fails to deal fairly with his associate even though he may not agree with him. We have a clipping laid away in our filing cases, evidently taken from an optical magazine, which we shall quote with the expression of regret that we cannot give the writer's name, since the clipping is but an excerpt from the article in which it appeared. However, possibly it is just as well, since we radically disagree with most of the writer's statements. The clipping referred to reads: "There are some children who habitually read and write at too short a distance. Their parents and teachers are contin- ually telling them not to get so close to the slate or paper, but they persist in the bad habits, which undoubtedly often lead to myopia or strabismus. I believe these children can only use their eyes in comfort at such a close range. The trouble is a spasvi of accommodation y that comes on when they do close work. They may try to see well at thirteen inches but the eyes -i^ant to focus at ten inches. So they move up close and keep on coming closer until the effort put in the ciliary becomes sufficient in amount so that coyivergence and accomjnodation balance.^ ivhen they feel cotnfortable. We might give such children concave lenses to read with, though in so doing we would make ourselves liable to charges of optometric incompetency, or what would be better, a pair of prisms might be worn to relieve the convergence and, therefore, reduce the ciliary innervation. As a matter of fact, when parents become alarmed by this habit in children and have them examined for glasses, the refractionist thinks that he has done the right thing when he has corrected the refractive error for distance no matter how small it may be. There is only one certain proof of spasm of accommodation due to hyper- trophy of the ciliary and that is the development of latent error. All other methods are guesses that are just as apt to be wrong as right. When it comes to the other variety of spasm of accom- modation, that due to excessive innervation of the ciliary muscle^ the only proof of its relief is the comfort produced either by wearing minus lenses or prisms base out!' We have quoted this paragraph at length and italicized some of the portions with which we disagree. The statement "that such children use their eyes in comfort at such close range" is incorrect; there is no particular comfort involved in it but there is often vision which is apparently impossible at greater distance because of the increase ot sizes of retinal images and other physiological factors to which reference has been made several times in these pages. By carefully watching such children one is often led to the conclusion that the major portion of this very close reading is done monocularly, since such children move their heads, almost from letter to letter, instead of their eyes and invariably keep throwing up a hand and rubbing one eye, usually the left, or more specifically, the eye with poorer Course No. 14 Page 45 vision. Squint or strabismus, in the proper significance of the term, does not in general develop after the age of six or seven years when the fusion faculty has, according to Worth, been fully developed. Certain it is, however, that troublesome and equally disturbing heterophorias may develop. Furthermore, it is stated that "they may try to see well at thirteen inches but the eyes want to focus at ten inches." If such were true then such eyes would, in attempting to read at thirteen inches, endeavor to focus or would focus at ten inches, hence if one eye isoccluded and the skiascope carrying a printed card is used at thirteen inches, fixation and observation being one and the same point, while the full distance correction is worn, such eyes should exhibit or evidence a myopic condition corrigible by minus lenses and reading would be made possible at such a distance. The same criterion would hold in the binocular use of dynamic skiametry unless a reasonably large heterophoric condition at near should exist. We have to say that we have never seen a case which fulfills the conditions which we have specified above. That by "moving up closer until the effort put in the ciliary becomes sufficient in amount so that convergence and accom- modation balance, when they feel comfortable" is impossible. For if the ciliary response is not normal^ the associated innervation to the convergence will not be normal and the burden ivill be throv:n upon the fusional convergence centers (either divergent or con- vergent as the case may be). In fact, in very young children in which strabismi develop or bad muscle imbalances are set up, one of the primary causes underlying the same is the breaking down of the fusional impulses under excessive load or burden. Moreover, in nearly all cases of a similar nature to those under discussion, dynamic skiametry when practiced at thirteen inches, with either binocular or monocular (one eye excluded) fixation, shows that the accommodative resources are in need of con- siderable additional assistance at the reading point. And again, in mose cases of this character, the accommodati'ce- convergence tests at thirteen inches show a condition of esophoria indicating that the innervation as delivered through the asso- ciated accommodative channels is more than ample but that lenticular changes do not normally occur; there is, in part at least, a paresis of the ciliary. The use, therefore, of minus lenses in such cases, unless they be used in rhythmic exercising as recommended by Savage, would be in general absolutely irre- concilable with the demands in such conditions, since it would add to the burdens of the already overtaxed or irresponsive accommodative action and would increase the accommodative- convergence. The pris?ns, base in, to relieve the fusional con- vergence would be more logical certainly, since this would leave the convergence and actual accommodative points more nearly at the same point by virtue of the fact that they would thus relieve and thereby make available an equal quantity of fusional convergence. However, such prisms cannot reduce ciliary inner- Course No. 14 Page 46 vation; the only way to reduce ciliary innervation is by the use ot convex lenses. One can, however, add to or reduce from the load upon the fusional convergence by the use of prisms. We are positive that the best practitioners of visual optics, opto- metry, or ophthalmology would agree that, in cases such as we have commented upon, the maximum convex lens correction wearable, with a fair degree (8/10) of normal acuity, should be initially prescribed and the seat of the subnormal accommo- dation determined. We likewise feel that in many cases an auxiliary pair of reading glasses to be worn when engaged at close work for any length of time should be prescribed and used until further tests show that they can be discarded. Ciliary spasms do not in general reveal themselves by a reduction in the hyperopic distance error at near-points as evidenced by dynamic skiametry; rather do they appear to be alleviated and in large part reduced as convex lens power is added under the dynamic skiametric procedure. This is to my mind one of the most valuable assets of dynamic skiametry, whether we call such conditions spasms of accommodation, or subnormal, or depleted accommodation. For at the reading distance a con- siderable expenditure of energy is involved, and a relaxation of the ciliary may be more readily induced by the offering of external lens assistance under these conditions than at infinity; or, in cases of subnormal or depleted accommodation as properly distinguished from spasm of accommodation, additional convex power will be accepted in the interest of accommodative effi- ciency and the proper correlation of accommodative-convergence and accommodation. The writer thinks there are many reasons why the ciliary, becoming with time more or less hypertrophied, may become abnormal in its functions and, therefore, demand excessive innervation for the accomplishment of its function in the processes of accommodation, or yet again, because of its abnormal condition and abnormal action upon the lens, inter- fere with the lenticular nutritive processes and thereby produce an abnormal condition of non-elasticity of the lens, thus ulti- mately demanding an abnormal innervation to produce any specified accommodative change. Before rehearsing in detail a case involving pseudo near- points and restricted amplitudes of accommodation, we quote several sections from various portions of the Jmcricay^ Ency- clopedia of Ophthalmology upon Spasm of Accommodation, Accommodative Weakness, Anemia in Eye Diseases and Chlorosis. Spasms of Accommodation. "If the pupil is much con- tracted, the near-point approaches the eye, and the range of accommodation is apparently increased. Generally, however, the near-point is not nearer to the eye that it can be brought by strong voluntary effort at accommodation. The far-point in such cases approaches the near-point more or less, and the Course No. 14 Page 47 range of accommodation is shortened and this certainly suggests myopia. Other causes of accommodative cramp are hysteria, irritation of the eye from injury and inflammatory changes." Accommodation, Weakness and Paresis of. "As Hess points out, the old idea that a normal near-point indicates normal function of the ciliary muscles is not noticed in accommodation until it is greater than the latent accommodation. Owing to the fact that the latter increases with advancing years, old people may be afflicted with a considerable paresis of the muscles and still the near-point be normal. This fact has been frequently overlooked. ... If we read that a patient fifty or sixty years of age has a normal near-point, and from this draw the conclusion that he has a normal accommodation, we must see at once that such a conclusion is not tenable, since the ciliary muscle may be completely paralyzed regardless of the fact that the accommodation is normal. It is for this reason that sub- jective disturbances resulting from ciliary paresis or weakness must in young persons be more pronounced than, ceteris paribus, in older people. Moreover, such disturbances are less marked in myopes than in emmetropes and less in the latter than in hyperopes. Common to all these disturbances is this recession of the near-point while the far-point remains in its normal locality. The most common clinical cause of accommodation, paresis is diphtheria, which affects the ciliary muscle only, the iris mus- culature remaining intact. The paresis usually occurs in from two to three weeks after the diphtheric infection, and in most cases recovery is complete after three or four weeks. Among other causes of paretic accommodation are: Partial or total paresis of the third nerve, various cerebrospinal diseases, hysteria and a number of intoxications — ptomaine poisoning,^ for example." Anemia in Eye Diseases. "These signs of a general blood change are most commonly associated with insufficiency' of accomfJ2odation — inability to read, fatigue of and pains in the eyes, etc. Deposits in the retina and choroid and even neuro- retinitis with hemorrhages also exist now and then. The specific new formations in the lymph glands and spleen, particularly those that mark the so-called leukemia, furnish another example of intoxication, with definite ocular changes." Chlorosis — Ocular Sy?nptoms of. "The photophobia and irritability often observed in the eyes of chlorotics are usually traceable to conjunctivitis and blepharitis and these again may result from overta~xing of a weakened accommodation which often leads to hyperemia of both the external and internal eye." Illustrative Case A. A. E. G. A colored boy, ten years of age. His ocular history evidenced no symptoms of particular interest other than that he did not see well at distance, could not read his school books readily, had had styes and granular lids. He had had diphtheria and scarlet fever when five or six Course No. 14 Page 48 years old. He had been a sufferer, so his mother reported, from "sick stomach" and some dizziness and that this had come on after the scarlet fever. Medical examination made previous to our seeing the boy had disclosed no ear, nose, throat or dental troubles. Tonsils had been removed. Static retinoscopy disclosed: O. S.+0.5 D. S.3 — -37 cyl. ax. 90, O. S. + i D. S.3 — -37 cyl. ax. 90. The ophthalmometer showed a corneal astigmatism of about one-half diopter against the rule. Subjectively, O. D.+0.25 D. S.O+0.37 cyl. ax. 180 and O. S. + 0.5 D. S.C+0.37 cyl. ax. 180 gave ¥ = 20^20. The addition of O. U.+0.25 D. S. gave V = 8/io easily but 10/10 with difficulty. Dynamic skiametry showed O. U. + 2.25 D. S.O + 0.5 cyl. ax. 180 with "fixation and observation at the normal reading distance." The monocular accommodation tests evi- denced the fact that the boy could not read No. 3 Jaeger (V = o.75 D) at thirteen inches, with each eye under test separ- ately, wearing the distance correction. But by bringing the test-type to within 5 inches of his eye he could read the No. 2 type. An examination of his pupils showed that they were very constricted and did not relax normally in the dark. The ophthal- moscopic examination showed a slightly congested nerve head; it could have been passed, however, as being normal had all other ocular conditions been satisfactory. For reading at thirteen inches it was found that O. D. + 1.5 D. S.C+0.37 cyl. ax. 180 and O. S.-f 1.62 D. S.3+0-37 cyl. ax. 180 permitted of a reading of No. 2 Jaeger with a range of about a foot to fifteen inches. The muscle tests, wearing the binocular distance correction, evidenced 2A of esophoria and 7A of esophoria at the reading point. The reserve convergence amounted, at thirteen inches fixation, to some 30A. A colleague of mine, an ophthalmologist, using atropin, determined the maximum distance correction as O. U. + 1.25 D. S. 0+0.37 cyl. ax. 180. A thorough systemic examination of the boy was made and he was put under medical treatment for gastro-intestinal auto- intoxication. We supplied him for distance the following cor- rection: O. D. + .75 D.S.C + .37 cyl. ax. iSoandO. S. + .87 D. S.C + •37 cyl. ax. 180, and gave as an additional pair for reading purposes O. D.+ 1.5 D. S.C + .37 cyl. ax. 180 and O. S.+ 1.62 D. S.O + -37 cyl. ax. 180. Several examinations made in the interim between initial and last visit demonstrated that normal accommodative action and range were returning. Today the young man is wearing O. D. + i D. S.O + -37 cyl. ax. 180 and O. S.+ 1.12 D. S.C + -37 cyl. ax. 180 with slightly blurred distance vision but with comfort and ease at reading, demon- strating some six to seven diopters of accommodation under the concave lens method of testing, using No. 2 Jaeger type, at thirteen inches. Course No. 14 Page 49 Illustrative Case B. Miss M. F., age ten years, presented herself and complained of incessant headaches, chiefly frontal and super-orbital in character, which came on generally after being in school and in getting her lessons at night. Her history disclosed the fact that she had suffered from typhoid fever, fol- lowed almost immediately by diphtheria, some two years pre- vious to our seeing her. She has had trouble with her eyes ever since. One of the young students in a clinic made the following static retinoscopic and subjective findings. Static retinoscopy": -O. D. + 0.5 D. S.C-.25 ax. 135; O. S.4-.75 cyl. ax. 90. Subjectively, the binocular tests showed that O. D.-j-O — 0.25 ax. 135 and O. S. + .373-I-.75 cyl. ax. 90 gave V = 10/10 with some difficulty. The comparison tests at twenty feet, using 2A base up and down respectively before the eyes, disclosed about equally good acuity conditions. Wearing the distance correc- tion the muscular tonicity tests at twenty feet disclosed ortho- phoria both laterally and vertically. At 13 inches the dot and line test, using the Maddox double prism before one eye, evi- denced 6A of es' phoria and slight right hyperphoria. Upon instituting the tests upon the amplitude of accommodation it was discovered that this young lady could not read No. 1 Jaeger tvpe at 13 inches, but that she could read it monocularly or binocularly with a fair degree of ease and certainty at 6 inches, the distance corrections being worn during these investigations. The subjective binocular amplitude of accommodation, there- fore, amounted to 7 D. as a maximum when taken under the most advantageous circumstances. By the concave-at-distance method (see The Keystone Magazine of Optometry^ Vol. 12, page 471) there was disclosed the fact that the patient could not read any of the V = 20/20 line through —3 D. S., the patient wearing the static subjective binocular findings, either monoc- ularly or binocularly, even under most persistent encouragement and goading on the examiner's part. This demonstrated con- clusively that the subject under examination was not possessed of more than a third to a half of the accommodation as apparently indicated by the near-point test and that, therefore, these near- point findings upon the accommodative amplitude were pseudo. In other words, this simple test with —3 D. S. showed, in the case in question, that the positive part of the relative accommo- dation was abnormally low. Likewise the tests at the thirteen inch point demonstrated that, with convergence constant, the relation between the positive and negative portions of the relative accommodation was such that accommodation could not be comfortably maintained. Attention needs to be called to the important relation which exists between these two parts of the relative accommodation. Donders stated, emphasizing by the use of italics {Accommodation and Refraction of the Eye^ page 114) that "The accommodation can be maintained only for a distance at ivhich, in reference to the negative party the positive part of the relative range of the accommodation is tolerably great." Course No. 14 Page 50 Howe, in his "Muscles of the Eye" Vol. i, page 339, writes upon this important topic as follows: "In our studies of the patho- logical conditions of the muscles we find the most important and apparently the most frequent anomalies are those which involve the ciliary muscle. Therefore, even in routine examinations and at the first visit, it is desirable to determine whether the action of that muscle is normal, or excessive, or insufficient. At least a general idea as to this power of the ciliary muscle is shown by placing a minus 3 glass before each eye and asking the patient to read again the distant test-type. I have learned to regard this as oyjc of our most important steps. For if, after the ciliary muscles have had a minute or two in which to adjust themselves, the person can read as well as before, then we know at once, at least in a general way, that there is no imperfection in the power of the ciliary muscle apart from convergence. If the person cannot overcome these or weaker minus glasses in proportion to his age or in proportion to the ametropia, then we at once suspect some insufficient power of the ciliary muscles. Even when such insufficient accommodation does exist, there may be little or no discomfort at near work, especially if the extraocular muscles are exceptionally strong or the general condition or the occupation of the individual unusually favorable. But ordinarily if the positive part of the relative accommodation (note by present writer: this is tested through the use of minus lenses) is insufficient with parallel axes, and also with convergence at one-third of a meter, and if discomfort and headache do exist, then that clue should be followed up. The examinations should be repeated at first roughly, if desired, with convergence at one-half or one-quarter of a meter. But if this evidence points in the same direction, and if the discomfort continues even when other possible causes of the difficulty are eliminated, then it is usually worth while to make the data more complete Of late years American ophthalmologists particularly have taken great pains to determine the condition of the extraocular muscles and have been so engrossed with these alone that physi- ological facts concerning the intraocular muscles which were demonstrated long ago and which are still of the utmost impor- tance have been forgotten." Dynam'c skiametry, with fixation and observation at 13 inches, indicated: O. b. + 2.75 D. S.^ — -37 ^^- ^3S ^^^ O- S. -i-2.5 D. S.3 + -75 ^^- 9°- These lens quantities represent the totals inserted before the eyes in order to obtain neutral shadows. The skiascopic shadows were rather erratic in this case and are worthy of more than passing comment. With the static retin- oscopic findings inserted before the eyes, initially, the shadows were decidedly "with." The addition of O. U.-I-0.5 D. S. pro- duced for the moment neutrality of motion only to give way to a "with" motion, ultimately made neutral by means of the lenticular findings recorded in the opening sentence of this Course No. 14 Page 51 paragraph. There is some evidence, therefore, of ciliary spasm from the behavior of the skiascopic shadows, for apparently a condition of neutrality gave way to indications of further cor- rigible hyperopia or further demands on the part of the accom- modation as the lenticular assistance offered to the ciliary in the interests of relaxation progressed. From the evidence as gathered from all possible tests the writer is of the opinion that the major portion of the added spherical power found by the dynamic method was in the interest of alleviating a ciliary spasm and in aiding an impaired and insufficient lenticular action; largely, however, the former of the two. Tests upon the positive and negative reserve convergences as well as duction tests at twenty feet indicated that there were no muscular derangements or innervational defects of a character to influence or interfere with the accommodative action. The patient, irrespective of her age (10 years), was given prescrip- tions for two pair of glasses, one for distance wear and one for reading. For distance we gave O. D. + 1.25 D. S-C" -25 ax. 135 and O. S. + 1.25 D. S.C--75 ax. 180, giving V = 8/io with some difficulty. For reading she was given O. D.-(-2 D. S.3 -.25 ax. 135 and O. S. + 2.25 D. S.C-.75 ax. 180. These latter gave a visual acuity binocularly of 6/10 at best. The subjective accommodative tests at 13 inches demonstrated that, equipped with the reading correction, she could read No. 2 Jaeger with some degree of ease and that her range extended from 7 inches to 18 inches. The patient was instructed to wear the distance glasses constantly except during study hours or other periods of close work, when the reading glasses were to be substituted. This she did for a period of six months. A re- examination at the end of that time showed that her distance correction could be increased and that the accommodative reserve at thirteen inches had increased to about 2 D. in each eye, thus indicating an accommodative amplitude of 5 D. The head- aches had entirely disappeared. We gave her at this second examination O. D.-f 1.75 D. S.C--^5 ax. 135 and O. S.-f-2 D. S. 3 — .62 ax. 180 for constant wear. These have proven entirely satisfactory, although they did not afford for a few weeks after their prescription an acuity quite equal to V = 8 10. IV. Dynamic Cross-Cylinder Method The late R. M. Lockwood wrote many deliqhtful articles upon many scientific subjects. None of those have been of more interest to the writer than his papers on "Cylinders and Cross Cylinders," appearing in the Optical Journal. We feel that, in discussing the dynamic cross-cylinder method, we cannot improve upon Lockwood's very clear presentation. We are therefore quoting at length from one of his papers. {Optical Journal^ Vol. 43, page 955, 1919.) Course No. 14 Page 52 "When, as a result of our tests, an eye has been made emme- tropic by means of lenses, and attention is paid to the type on the near chart, there passes an impulse from the retina to the brain as the result of which there comes back a return impulse which innervates the ciliary muscle, and causes that muscle to so alter its tension that the object of attention is focused more or less well on the retina. If this innervation is not just right, it is quite conceivable that other corrective efforts follow, and that in the end the best attainable image possible for that eye is had, or else there is a compromise, the innervation resulting in a focus that is slightly imperfect or blurred, because such an imperfection is less irritating than the extra, exact inner- vation of the ciliary necessary to reduce the imperfection. "Suppose that a certain eye is being used at a distance of 16 inches, but the near-point, (wearing the full distance cor- rection) is only at 18 inches; this is clearly a case of insufficient accommodation; the near-point might be even closer, and yet with due regard to the need of reserve accommodation there would still be an insufficiency. But take another case where the patient is young, and the near-point at eight inches, say; and yet when the eyes are used at a distance of 16 inches the accommodation falls short because of a faulty innervation to the ciliary muscle. Such a case is not presbyopic; it is one of inefficiency of the accommodation, or pseudo-presbyopia. In either case the extra plus that must be put before the eye to cause the innervation to act just right so that focusing is neither under nor over is some sort of a measure of the dynamic error in the accommodation. To get this measure in each and every case and incidentally to discover how much accommodation must be kept in reserve in order to have theoretically perfectly comfortable vision for near, we use the cross-cylinder dynamic method. Figure 4. — Lockwood's Chart for Use in the Dynamic Cross- Cvlinder Method. Course No. 14 Page 53 "If the refractive error in a given eye has been determined, and this has been checked on the near chart to see that near vision is clear and sharp, then by placing before that eye a compound equivalent to a cross-cylinder, say the C compound ( + 0.50 sph.3~i- cyl.) we will create a false astigmatism which results in one principal meridian being made hypermetropic and the other myopic to the same amount. If the eye is looking at the test-type at the time the type will be blurred but if the fixa- tion object is a T chart (Fig. 4) and the arms of the T are made to agree with the principal meridians of the false astigmatism, then, if before applying the test the eye was in exact focus, there will be no perceptible difference in the clearness of the two sets of lines. If the tocus was not exact, then the test will show a difference, and the spherical part of thejcorrectionfmust be altered until the difference does not show." The technique of the method may be tried out as follows: (i) Set up the full distance correction and, if necessary for clear vision, (presbyopic cases) add sufficient plus spherical power for the purpose. (2) Arrange the fixation card (Fig. 4) on a stand or in a holder so that the sets of lines are truly horizontal and vertical (other directions can be used if preferred). (3) Have ready a +0.50 sph.Q— i- cyl. testing compound (equivalent to a cross-cylinder), minus marks held to exactly agree in direction with the arms of the T testing chart. Drop the same in front of the distance correction and have the patient announce whether both sets of lines are seen equally clear, or whether there is a difference. If there is a difference, and the lines agreeing in direction with the minus cylinder marks are clearest, the spherical power in the frame must be made less plus, etc., until there is a balance. The extra plus that must be added to the distance full correction to get perfectness of focus is a measure of the accommodative error. "The above will apply to all cases where the contraction of the pupils tor near vision does not produce a change in the cylindrical finding, which should be made before the dynamic test is tried. "Insufficiency of accommodation is far from uncommon in young eyes, and should be looked for in every case, though there is a difference of opinion as to what should be done with it when found. Some say that nothing should be done; that the full correction of the refractive error will make the eye normal, and that an eye made normal, barring presbyopia, will function perfectly. Others hold that whatever defect of accommodation is determined by the cross-cylinder dynamic method shall be fully corrected regardless of age. Still others say the dynamic findings should be taken into consideration and if the symptoms warrant it, there should be plus help for near. Personally, I (Lockwood) favor this latter view. Course No. 14 Page 54 "Example i. Refractive error is corrected by +1. sph.O + 1. cyl. 180°. Checked up for near vision, the cylinder finding remains unchanged; punctum proximum is at eight inches. Using the dynamic cross-cylinder method an extra +0.75 sphere is needed to get perfect focus. Glasses have never been worn before, and there are no headaches; only decreased visual acuity. In this case the +1. sph.^i- cyl- ax. 180 corrects the distance error; also corrects most of the near error, so it can be given for constant wear. "Example 2. Distance correction is +0.25 sphere; no astigmatism, far or near; dynamic cross-cylinder method indi- cates that +1.25 must be added to get perfect focus at the reading distance. No trouble in distance vision, but headaches and swimming of letters in near work after an hour or so; punc- tum proximum 73'2 inches. By the old methods, the prescrip- tion would be +0.25 sph. for constant wear. I would favor instead +1. sphere for close work, no glasses for distance, etc." The cross-cylinder dynamic test can be used to differentiate between the forced and comfortable amplitude of accommoda- tion. To this end there should be a set of T charts, say three of them, one-half the size of that shown in iMg. 4, one the same size and one of twice the size. After the full distance correction has been determined and put before the eye under test the cross-cylinder is added to it and the smallest T chart brought close to the eye and slowly withdrawn until both lines come equally clear. If this does not happen by the time a distance of 12 inches, say, is reached, the second sized T chart should be substituted out to about 24 inches, and then the large T chart used up to about 40 inches, until the point of equalization is found. Converted into diopters we get the amplitude of com- fortable accommodation. If the equalizing point is still farther away, we increase the sphere in the frame by i. D. and repeat the test making allowance in the calculation for the i. D., etc. The forced accommodation is found in any of the usual ways. By comparing the two results we get an idea of how much (theoretically) accommodation should be kept in reserve in the given case. "Example 3. With distance correction in place the punctum proximum found in the usual way is at seven inches which equals 5.75 D. amplitude. The P. P. found by the dynamic cross- cylinder test is at ten inches which equals 4. D. The reserve accommodation in this case should be 1.75 D. "Example 4. The amplitude of accommodation found in the usual way is 7. D. By the cross-cylinder dynamic test alone the comfortable near-point cannot be located. Adding a plus i. D. to correction it is now located at 26 inches. This distance equals 1.50 D.; making allowance for the extra i. D. this is reduced to 0.50 D. Hence in this case for perfect comfort there Course No. 14 Page 55 should be a reserve of 6.50 D. which is markedly in excess of the usual average of one-third to one-half." V. Objective Method of Determining the Amplitude of Accommodation In 1917 the writer proposed an objective method of deter- mining amplitudes of accommodation. The essential optical principles underlying these tests are those involved in skiametry and the applications of the laws ot conjugacy of foci. •"^N^ Figures 5, 6 and 7 show diagrammatically the general modus operandi in the monocular method. Each eye should be, in turn, occluded and its ac- commodative range investigated, since some of the most interesting and important cases from the ocular economic standpoint are those involving marked differences between the acommodative re- sources of the two eyes. In practice matters are so arranged that the object viewed (Fig. 5) shall be reasonably illu- minated. The Hooding of the room with artificial light, if this be by indirect or semi-indirect methods of lighting, is not objectionable except from the opera- tor's standpoint. With experience, however, one can use retinoscopic methods and follow the reflexes with ease and accuracy under almost any subdued lumin- ous surroundings. The writer invariably uses the self-luminous instrument in these tests. The patient is given a line of type printed in about 10 or 12 point type upon a card about one- quarter inch wide and fastened to some convenient holder such as illustrated in Figure 5. Or a single line ruled on a card or a pencil will serve satisfactorily as a fixation object, but there is not the incentive to full accommodation as when reading is demanded. The full monocular distance finding, affording as nearly V = 20/20 as possible, is inserted before the eye to be tested. The patient is then given the test object— which he holds initially at about 13 inches — and is told to read the letters. Or the operator may hold the test object in one hand and approach it toward the patient. In general we have the patient hold the card slightly to the nasal side during the examination of either eye while we proceed to examine skiamet- rically from the temporal side and as close to the visual line as possible. Course No. 14 Page 56 Figure 6. — The Optical Principles involved in the Objective Test for the Amplitude of Accommodation. In Figurfe 6 there is represented the optical and ocular conditions present when the retina and the object viewed are conjugate points and the exact or requisite number of diopters of accommodation demanded for the point fixed are supplied. Under these conditions, therefore, with the accommodative point kept constant at F and the mirror A in the same plane a neutral shadow condition should obtain and by moving the retinoscope to C — an inch nearer the eye — a hyperopic con- dition should be revealed or by withdrawing an inch farther from the eye, as at 5, a myopic condition should be evidenced. By then moving or having the patient move the test-object nearer the eye the actual near-point will be found as soon as the retinoscopic mirror has to be operated in a plane back of the fixation point in order to obtain a neutral shadow. These are ideal conditions in that we are assuming a perfectly inner- vated and functioning ciliary and lenticular action, and that there is no lag of accommodation behind convergence as dis- cussed elsewhere. {Vide Sheard: Dynamic Skia7netry, 1920.) In short, we are here writing of ideal and physically perfect conditions. In general, however, it is found that when the patient, wearing the full distance correction, reads monocularly the letters (which, by the bye, may be as small as the patient can see), there is a "with" or hyperopic motion — using the plane mirror -- indicating that the point conjugate to the retina in the eye opti- cally statically perfect is not at the position of the object viewed but at a point somewhat behind that point, /. e., farther from the eye. In Figure 7A, let F be the point viewed and A the position of the operator's mirror. If a certain test shows that DF is 10 inches (4D) and DA is 13 inches (3D) we should con- clude that the accommodation actually available at ten inches is sufficient only for the optical conjugacy at 13 inches, hence indicating the need of a diopter of lenticular assistance. We must, however, bear in mind the probable physiological lag of accommodation which amounts, in the average case, to about one-half diopter. By approaching the object closer and closer Course Xo. 14 Page 57 CAB Figure 7A. — Illustrating the Procedure in Obtaining Skiametric Determinations of the Amplitude of Accommodation. to the eye a point will finally be found such that no nearer approach of the test-object to the eye changes the neutral condition of reflex as skiascopically observed at the closest point to the eye at which a neutral shadow is obtained. In testing, therefore, for the near-point objectively we proceed as follows: The patient draws the test-object as near the eye as will still permit of its reading. To the observer at thirteen inches the skiascopic reflex will show an "against" or myc pic condition indicating that he is outside of the optical ocular far-point dynamically considered. The operator then moves forward until he obtains the neutral shadow position. The test-object is then to be carried still closer to the eye (blurred images make no difi^erence) and the nearest point of neutral shadow found and measured. This gives the apparent near- point under whatever ocular conditions the test is made (ordi- narily when wearing the distance correction) and from it the range and amplitude of accommodation are easily determined. We measure the distance DA (Figure 7A) and not FD. We occasionally vary this test and, with observation and fixation at thirteen inches, produce neutralization of shadow at this point and then proceed as outlined above. We are, however, partial to the test in which the static finding is worn. The method is certainly very simple and quickly carried out. The question arises: Are there any inherent errors? Yes; those of observation and ot optical imperfections, lack of response on the part of the person under test, and the difficulties of making accurate measurements of distances. For this latter purpose we use a light-weight, narrow tape-measure, one end fastened to the trial frame with due allowance for distance from the cornea, and the other end weighted, the tape when in use being carried between the finger and thumb of the hand holding the retin- oscope. These tests must certainly suggest themselves to the reader as being most valuable, especially in finding the range and amplitude of accommodation in children (for one can employ Course No. 14 Page 58 Figure 7B. — Illustrating the Procedure in Obtaining Skiametric Determinations of the Amptitude of Accommodation. some colored pictures pasted on the rear side of the test-object shown in Figure 5); in presbyopia; in subnormal accommoda- tion; in excessive accommodation; in amblyopia, when we are uncertain whether or not accommodation is still active because of the uncertainty of subjective tests by virtue of the reduced visual acuity, and in anisometropia. Likewise we are provided with an objective method which tells us whether or not accommodation is proportionately enforced in those rather frequent cases, already alluded to, in which the patient, usually young in years, is not able to read fine print at fourteen inches but can read it when brought up very close to the eye. Our answer is that these tests demon- strate the universality of lack of proportionate accommodative action and that such type is read at points abnormally close to the eye because of increased sizes of retinal images, con- striction of pupil and narrowing of the palpebral fissure. Furthermore, these objective tests show that the ampli- tudes of accommodation are in closer agreement with the results tabulated in a preceding section under the concave-at-near method than they are with monocular near-points and binocular concave-at-distance methods. Course No. 14 Page 59 Chapter IV. — Anomalies of Accommodation Having briefly outlined some of the salient anatomical and physiological facts relative to the accommodative apparatus of the eye and having pointed out the fact that contraction of the ciliary muscle and that of the sphincter of the pupil are almost always simultaneously exerted while relaxation of the accommo- dation is usually accompanied by dilatation of the pupil, and, in addition, having called attention to the basic principle that the "capital symptom of an anomaly of the accommodation is the change in position of the punctum proximum or of the punctum remotum, as well as the visual disturbances resulting from it" (Landolt), we pass on to consider what Bonders has entitled, in his classic work on The Accotnmodation and the Refraction of the Eye, morbid paralysis of accommodation. We are taking the liberty of quoting verbatim upon this topic from the writings of this celebrated writer, who was, during his lifetime, the pro- fessor of physiology and ophthalmology in the University of Utrecht. We may be pardoned for so doing because these writings are rather difficult to secure and hence are not available to many students and practitioners and for the further reason that our store of information upon paralysis and paresis of accommodation has not been greatly increased since the time of Bonders. (The year 1864 marks the appearance of his treatise on The Accoinmodation and Refraction of the Eye.) At least many of the fundamental and essential points relative to the paresis and paralysis of accommodation are included in the essay from which we shall quote. Paralysis of Accommodation "Paralysis of accommodation as disease is by no means an unusual occurrence. Emmetropic and ametropic eyes are alike liable to it. It occurs too at every age, but in old persons, who have already lost there accommodation by senile changes, it is of little importance. As we know that the accommodation is effected exclusively by the internal muscles of the eye, we can seek paralysis also only in . the fibers of the short root of the ciliary ganglion. Now, in fact, it often happens that only these fibers are paralyzed, and in this case we have paralysis of accom- modation alone; except that paralysis of the sphincter pupillae, which derives its motor fibers from the same root, is usually combined therewith. But in about an equal number of cases there exists at the same time paralysis of other fibers of the oculo-motor nerve, and not infrequently the paralysis extends even to all branches of this nerve. It is remarkable that while paralysis of accommodation very often occurs separately, paralysis in the domain of the oculo-motor nerve is comparatively rarely met with, without paralysis of accommodation. I may add that, so far as my experience goes, uncomplicated paralysis of accommodation occurs much more frequently in women, Course No. 14 Page 60 often too in children; paralysis of the oculo-motor nerve on the contrary, including paralysis of the accommodation, is much more frequently found in men and ordinarily not until after the twenty-fifth year. In either case, the paralysis is rarely complete; generally speaking, it is only paresis, inasmuch as a certain though usually only a slight degree of accommodation has remained. "Uncomplicated paralysis of accommodation has only one objective symptom: Dilatation and immobility of the pupil. The dilatation is not considerable, tor even with complete paralysis a wider pupil than the normal in the dark is not to be expected. Nevertheless, in complete paralysis not a trace of either accommodative or of reflex movement is to be seen. But I may add that these cases are extremely rare. Further, the connection between paralysis of the pupil and of accommoda- tion cannot be called absolute; once I found satisfactory accom- modation still co-existent with absolute immobility of the pupil. In one instance, too, paralysis of accommodation disappeared without a return of the mobility of the pupil, and, on the other hand, with perfect or almost perfect loss of accommodation, the motion of the pupil may be but little disturbed." Errors of Refraction in Their Relation to Paresis and Paralysis of Accommodation "From all this it is evident that the subjective phenomena are the most important. Now, upon these the refraction of the eye has a considerable influence. "Myopes whose farthest point is not more than fourteen inches from the eye find no difficulty in reading, for this point remains unchanged, and although their nearest point then coincides with it, they see, with unalterable refraction, per- fectly acutely at the distance of fourteen inches or less. The disturbance is confined to this, that, on the one hand, objects at a greater distance appear, on account of the greater circles of diffusion of the larger pupil, more diffuse than usual — on the other, that within the distance of their combined nearest and farthest point, they cease to see acutely. Both disadvantages are in great part removed when the paralysis of accommoda- tion is incomplete, and we then hear a very few complaints from myopes. It is only when they wear neutralizing spectacles, and use them at their work, that they are on a footing with emmetropes. "Ernmetropes. — These, on the occurrence of paralysis of accommodation, immediately resort to the 'oculist.' They can no longer read nor write, and they are aware that an important disturbance exists; even when, as is usual, only one eye is affected, a certain dimness is, on account of the acute origin of the paralysis, forthwith observed, causing each eye to be sep- arately tried, and thus the lesion is discovered. (Note by present writer: How often, however, have practitioners found that Course No. 14. Page 61 this dimness is not discovered by the patient and no simple tests such as that involving the comparision of the eyes by trying each separately is ever, apparently, conceived of by the patient.) If we find that vision at a distance is acute, and with either concave or convex glasses becomes diffuse, while for near objects convex glasses are necessary, the diagnosis is made which finds only a still further confirmation in the torpidity of the dilated pupil. "The paralysis of accommodation is productive of yet greater disturbance in hypermetropes: not only for near, but also for distant objects, with respect to which an involuntary accommodation formerly overcame their hypermetropia, is their vision diflFuse. It is evident that such a condition suggests the idea of amblyopia. ... By attending to the direction, in any disturbance of vision, systematically to define with glasses the refraction, and the acuteness of vision in distant vision we shall be sure to avoid error; amblyopia is thereby forthwith excluded, and while the glasses required for distant vision are insufficient for seeing near objects, the paralysis of accommodation is recognized. "The phenomena are less characteristic when no complete paralysis but only paresis is present. The myope then often experiences no actual disturbance; the emmetrope complains ot fatigue only on tension for near objects, resembling the asthenopia of the hypermetrope; but the hypermetrope very rapidly experiences considerable asthenopia for near objects, and even difficulty in seeing acutely at a distance. In general, with paresis of accommodation, asthenopia very quickly occurs; in the first place, because the wider pupil requires more accurate accommodation to distinguish satisfactorily; in the second place, because, just as in atropia-paresis, the relative range of accommodation is very unfavorably situated; while with the maximum convergence, the closest point is found comparatively little farther from the eye; with medium convergence, only a slight tension of accommodation appears to be possible — sometimes in paresis of accommodation micropia is also com- plained of. . . . " Treatment of Paresis and Paralysis of Accommodation Bonders discusses at this point methods ot treatment tor paresis and paralysis of accommodation. Much of this is doubt- less antiquated and superseded by the modern rnethods and practices of refraction and medicine. The foregoing citations from Donders and others of a similar nature which might be quoted from various ophthalmological treatises and encyclo- pedias should serve to call the attention ot all eye practitioners to the condition of paresis and paralysis of the accommodation only or of the oculo-motor system and the probable symptoms and evidences of the presence thereof. These remarks should Course No. 14 Page 62 further serve to put the refractionist on his guard lest he fail to fully conserve the interests and possible longevity of his patient by failure to diagnose paretic and semi-paralytic conditions. Skill and thorough knowledge are needed in order to differentiate between cases demanding refractive treatment or assistance solely and those demanding all possible sources of help, both medical and non-medical. It may be, with propriety, very bluntly pointed out here, that the human race is said to be permeated and ravaged with syphilis through the sins of the sons as well as of the fathers "even unto the third and fourth generations" back. Perhaps it is true that, too often, apparently unsolvable ocular conditions, reduced acuity, weakened accom- modation and convergence are laid at the door of this disease for want of a better or more accurate diagnosis. Yet, it is true, that many of these paretic conditions, especially those involving accommodation and convergence, are attributable to primary or inherited ^syphilis. It, therefore, behooves all practitioners upon the eye to carefully investigate the powers and resources of the accommodation as well as other ocular functions. In nervous conditions all optical assistance possible should be afforded, but, as Bonders says, "where the nervous system is more generally implicated, regimen and treatment are directed to that condition, without special attention to the paralysis of accommodation." We close this series of quotations upon the morbid paralysis of accommodation as taken from Bonders by quoting that paragraph from his writings which deals with the optical treat- ment. While his remarks are rather indefinite, yet they bring to our attention suggestions which are eminently worth while and deserving of some personal thinking. He says: "Respecting the use of spectacles in paralysis of accommodation, it is almost sufficient to observe that there is scarcely ever any objection to bringing the point of distinct vision to the distance which the existing acuteness of vision and the nature of the work to be performed render desirable. Sometimes, however, especially when the paralysis is incomplete, we give weaker glasses, so that the tension required ensures practice of accommodation. But if asthenopia then occurs, we do not withhold stronger glasses. Whether in paralysis of accommodation of one eye the assist- ance of a convex glass is to be afforded must be judged from what has been said as to the use of glasses in difference ol refrac- tion of the two eyes. We should bear in mind that in the sta- tionary refraction of the one eye, the same glass can in this case be useful only for a given distance." Paralysis of Accommodation after Diphtheritis Diphtheria is a well-known infectious disease characterized by the formation of a membranous, fibrinous, whitish or grayish deposit at the seat of the infection. The characteristic lesion usually affects the throat and often the nasal passages and the Course No. 14 Page 63 larynx. The disease, in its many manifestations is due to a bacillus discovered in 1886 and called the Klebs-Loeffier bacillus. The effects of diphtheritic poison upon the ocular apparatus are somewhat varied. The eye is frequently the seat of post- diphtheritic lesions which occur in the form of paralysis or paresis. The favorite seat of the lesion is in the accommodative apparatus; the velum palati (soft palate), the extremities, the bladder and the rectum may also be affected. The extra-ocular muscles often do not escape and many permanently hetero- phoric or heterotropic conditions may be traced as the results of this disease. Ocular practitioners have on record the histories of many cases in which, in so far as can be ascertained, no vital disturbances of the oculo-motor apparatus existed previous to an attack of diphtheritis. The severity of the disease apparently has no connection with the degrees or varieties of ocular dis- turbances which may arise. It appears, however, that the ciliary muscles are more likely to be affected than any other portion of the muscular system with the exception of the velum palati. Failure of Accommodation and Alteration of the Static Refraction in Diabetes Various names are given this systemic condition known as diabetes. It is frequently referred to in literature as diabetes mellitus, saccharine diabetes and glycosuria. Fagge, in his work entitled Text Book of the Principles oj the Practice of Medi- cine^ Vol. II, 1 891, says that "it is not a disease of the kidneys, ol the urine, or of the blood, but is a derangement of the chemical labor of nutrition." One of the chief evidences of the presence of diabetes lies in the urinary analysis; the urine is abnormal in quantity and constitution. It is much paler than in healthy conditions, has a peculiar odor compared often to the smell of apples and has a high specific gravity — 1030 to 1045. The ocular lesions occurring in saccharine diabetes as portrayed by various writers are considerably different. Disease of almost every part of the ocular regime and its surroundings has been observed. In some cases it must be true that the ocular lesions should be regarded as an accidental complication of the general disease. However, in regard to certain ocular symptoms it has been well established that the diabetic condi- tion bears a definite causal relation. A careful study of ophthalmic literature leads to the con- clusion that disturbances of vision are of frequent occurrence in diabetes. We have, however, little guide as to their relative frequency. Thus one writer states that cataract is the most common eye affection in diabetes, while yet another writer shows by figures that, of cases coming under his observation, paralysis of accommodation was twice as frequent as cataract. And again, it seems impossible to make any decided statement Course No. 14 Page 64 as to the relation existing between the development of ocular lesions and the severity of the glycosuric attack. On the whole, however, we may believe that, with the exception of cataract, the ocular complications are more frequent in cases of a chronic character in which some of the general symptoms (such as emaciation and thirst) are not marked. It is true "that in not a few instances, indeed, the patient first comes under obser- vation in consequence of eye disease." The ocular complications of diabetes are: (i) Paralysis and paresis of accommodation; pupillary anomalies; alterations in the static refraction of the eye. (2) Affections of the extra-ocular muscles. (3) Inflammation of the iris, ciliary body and cornea. (4) Cataract. (5) Disease of the retina and vitreous. (6) Disease of the optic nerve. We are desirous of discussing chiefly only the first narnes of these complications. The others are as worthy of discussion hut their perusal by us would lead us too far astray from our selected field. Therefore, since complications involving accommodative paresis are the most common in diabetic conditions, it behooves the refractionist to make such accommodative tests and to refer his client, in any case of doubt or where the history or other corroborative evidence obtained by ophthalmoscopic examina- tion arouses a suspicion as to whether or not the ocular symptoms are not secondary to some fundamental systemic disorder, to competent medical practitioners for a further examination. J. B. Lawford, M. D., F. R. C. S., surgeon to the Royal London Ophthalmic Hospital, Moorfield, writing in 1900 on "Ocular Lesions Dependent Upon Disorders of the Secretory and Excretory Organs," says: "Failure of accommodation is, according to the majority of writers, one of the most common ocular symptoms in diabetes. The condition is generally one of limitation, /. c, of diminution in the range of accommodation, and seldom leads to complete loss of this power. Von Graefe {Archiv fur Ophthahwlogie, 1858) was the first to recognize this svmptom in diabetics, and since his time numerous confirmatory observations have been recorded (Nagel, Seegen, Rosenstem and others). It is met with in mild as well as in severe cases, and may be among the earliest evidences of disease. The onset, and especially the steady increase of presbyopia at an unusually earlv age, should excite suspicion of some general malady, and one of the most probable is diabetes. A case of Foerster's is recorded in which the premature onset of presbyopia led to the examina- tion of the urine and the discovery of glycosuria. A very similar instance was observed by Seegen {Dcr Diabetes Mellitus, Berlin, 1875). His patient was a young woman in whom failure of accommodation was noted, and who also complained of general Course No. 14 Page 65 muscular fatigue. The urine was found to contain 0.3 per cent, of sugar. In the majority of these cases no abnormality of the pupil in size or in reaction is present. In some instances, however, there is evidence of paralysis or paresis of the iris; bilateral and unilateral mydriasis have been noted, and loss of or deficiency of the pupillary reaction to light (Ogle and Testelin)." Paresis of Accommodation from Drugs In nearly all cases of poisoning in human beings the drug has entered the system through the stomach. Amaurosis may follow the ingestion of any of the alkaloids of cinchona bark; naturally the salts of quinine are the most potent. That the drug itself and not a concomitant disease is the cause of the amaurosis is established by those cases in which it was taken by healthy individuals, by experiments on animals and also on human beings (Barabaschew). The dose which may cause blindness varies from fifteen grains to one ounce in twenty-four hours. In mild cases or types of quinine intoxication there may be a temporary amblyopia without lesions of the fundus or diminished power of accommodation. If quinine-blindness has once occurred, relapses may be occasioned by small doses of the drug (Knapp, Nettleship). Paresis of Accommodation Due to Ptomaine Poisoning Cases of poisoning in human beings dependent upon pto- maines and toxalbumins have usually followed the ingestion of spoiled meat, fish, cream, pastry and so forth. Since many of the ptomaines are basis compounds closely simulating vegetable alkaloids — such as, for example, atropin — "it is not unnatural that the ocular symptoms would be analogous to those pro- duced by the vegetable drugs which these substances resemble in physiological action (de Schweinitz)." They are, therefore, dimness of vision or transitory amblyopia, together with a bilat- eral paresis of accommodation with or without mydriasis. Indeed, as de Schweinitz remarks, some of the most interesting obser- vations in ptomaine poisoning cases have to deal with paralyses and pareses of the ocular muscles. Paresis of Accommodation Due to Anemia The signs of a general blood change, known as anemia and chlorosis, are most commonly associated with insufficiency of accommodation — inability to read, fatigue of and pains in the eyes. "The photophobia and irritability often observed in the eyes of chlorotics are usually traceable to conjunctivitis and blepharitis, and these again may result from overtaxing of a weakened accommodation, which often leads to hyperemia of both the external and internal eye {American Encyclopedia of Ophthalmology, page 2068)." It should, however, be pointed out that optic nerve disorders, especially certain forms of neuritis, are much more certainlv and closelv related than are accommo- Course No. 14 Page 66 dative phenomena. For, as the writer on the subject of "Ocular Symptoms of Chlorosis" in the American Encyclopedia of Oph- thalmology says: "Outside of true neuritis optica — the causes of which may be intracranial — only a certain form of papillary congestion can be traced to a purely edematous process accom- panying a hyperemia. Vision may be normal or nearly normal and so continue a long time under these conditions. Occasion- ally the disc is much swollen, although the elevated papilla appears clear and transparent and has a faint, edematous appear- ance; in other cases it is a simple edema. The vessels are but little changed, although the retinal veins may appear darker, enlarged and tortuous. In some cases white opaque bands are seen in the papilla and white plaques have been observed in the retina not unlike those found in albuminuric retinitis. These hyperemic or inflammatory changes may go on to atrophy." Paralysis and Paresis of Accommodation from Dental Irritation Many observations have been made which demonstrate that there are affections of the eye to be attributed to decaying or decayed teeth. These cases cover such ocular affections as inflammation of the conjunctiva, cornea and iris, amblyopia and neuritis occurring in patients suf?"ering from dental disorders. Probably the most frequent ocular disturbance noted in con- nection with dental irritation is that of accommodative weakness. Schmidt {Archiv fur Ophthalmologic., Bd. XIV) has drawn atten- tion to this fact and has published a series of ninety-two obser- vations in seventy-three of which dental irritation was found co-existent with a limitation of the accommodation. Bruner {Annals of Ophthalmology., October, 1912) considers that ocular affections due to dental diseases may be divided into two classes: {a) Functional disturbances and {h) organic changes. The first of these may be due to an abscess or disease about the root of a tooth or to an impacted tooth. These reflex effects will be produced more frequently when the teeth of the upper jaw are at fault. This dental irritation may show itself in dis- turbances of the pupils or the motility of the iris on the side of the face affected, in the restriction of the range or complete paralysis of accommodation, spasm of the orbicularis, in dis- turbances in the muscle balance, in asthenopia or in amblyopia, more or less marked. These are entirely relieved in general upon removal of the causes of irritation. Schmidt found that the restriction of accommodation attributable to dental irritation was either bilateral or monocular (in the latter case, only on the side of the dental disturbance); that it was most frequent in the young, and that it amounted in some cases to as much as 5D or more. Schmidt attributes it to reflex increase of pressure in the eye, analogous to the restriction of accommodation observed as a preliminary symptom Course No. 14 Page 67 of glaucoma. It is probable, however, that when limitation of accommodation appears during dental disturbances, such as toothache, such limitation is due to a lack of sufficient inner- vation on account of the distressing pain. Likewise, muscular insufficiency and diplopia which occasionally occur are probably simply pareses due to weakened innervations. Paresis of Accommodation Due to Nervous Exhaustion and Nutritional Disturbances We have already called attention to the unfavorable in- fluences which a state of poor health has upon the energy of the ciliary muscle. "Any cause," as Landolt writes, "capable of impeding nutrition and determining a general depression of strength will, therefore, find an echo in the accommodative faculty." Thus it is not surprising that weakness of the accom- modation should have been pointed out in essential anemia and in the multitude of other symptomatic conditions, such as that which succeeds acute diseases, or which is provoked by lactation, alcoholism, venereal diseases, uterine lesions, abundant hemor- rhages, etc. Primitive lesions of the central nervous system, chiefly of the brain, are very frequently accompanied by paresis of accom- modation. "They are then concerned with the nuclei of origin of the common oculomotorius or the trunk itself of this nerve, which is changed by pressure, by inflammation or by destruc- tion. Simple vascular disturbances in this region are capable of producing a weakening of the accommodative faculty; anemia or hyperemia is sufficient without the existence of any more serious cause." We must, without doubt, refer to these anomalies of circu- lation the paralysis of the ciliary muscle observed in digestive troubles. "There is scarcely any other possible explanation," writes Landolt, "for the strange case published by von Hasner in which a young girl was regularly attacked, at each menstrual period, by a complete paralysis of the common oculomotorius, which disappeared at the end of three days, to be renewed at the following menstrual period." However, it is to be said that the ocular lesions which are described as taking place in the course of various disorders ot the digestive organs and tract must, in many instances at least, be regarded as having but an indirect connection with the gastric or other afl^ection. A causal relationship can be rarely established between ocular symptoms and general digestive troubles. But, in an indirect way, through interference with assimilation and nutrition, the gastric or intestinal disturbances may be a very important factor in the production, or aggrava- tion, at least, of certain anomalies pertaining to the innervations and responses of the various ocular muscles. Course No. 14 Page 68 Paresis and Paralysis of Accommodation Due to Glare R. S., aged twenty-nine years. Bookkeeper by vocation. His record card evidences the fact that he had been suffering from nervous troubles for about two years; that he had received competent medical attention; that his eyes had been examined both with and without cycloplegics several times during the preceding five years; that he could see clearly and do his close work as a bookkeeper with fair ease in the morning but that his eyes fatigued and severe frontal headaches developed toward evening almost every day. Our examinations led us to the conclusion that O. U. + i D. S. should satisfactorily relieve the eyes from the strain and symp- toms of which he complained; we found that he had been wearing glasses containing exactly this correction for over six months. Tonicity tests, the patient wearing the static findings, showed I A esophoria; the accommodative-convergence tests at thirteen inches showed 3A base in, which, allowing 6A as the normal physiologic exophoria, shows a slight overconvergence as asso- ciated with the act of accommodation. Objectively, the accom- modative amplitude was found to be 6D: subjectively, using the minus lens method and coercing the patient, we could draw out as high a value as 7.5 to 8 D. However, the ability to read fine type at thirteen inches was uncertain and fleeting through more than —3D. S. to — 4D. S. Tests made on the following day and in the morning hours, the patient having done no ocular work in the interim, showed nearly the same accommodative amplitude conditions but clearly evidenced the fact that the average reserve was higher than on the previous afternoon and showed less tendency to fluctuations, such as alternate periods of ability to read followed by indistinctness and blurriness. This young man came from a near-by town and having occasion to go into it a few days later, we promised to visit him at his place of work. In the meantime he was told to cease work and enjoy a few days' vacation. In due time we went to visit his workroom. The situation of side lights with respect to his bookkeeping desk, the marked contrast glare and the lack of sufficient general illumination led us to the conclusion that this man's eye troubles and headaches, if not in large measure his nervous troubles, were due to the conditions of lighting under which he was working. So we made the suggestion that the lighting conditions be remedied, and roughly sketched out the changes we thought best, namely, a well-distributed semi- indirect lighting system. Reasoning from cause to effect and vice versa, after the elimination of one probable or possible factor after another, we felt positive that the physical and mental welfare of this young man as well as that of other occupants of this room would, to say the least, be greatly improved by such changes. Suffice it to say that the alterations were made and that this young man gradually (in about two months' time) Course Xo. 14 Page 69 became relieved of all headaches and all ocular fatigue. The conclusions seem logical in this case; no factors were changed and no variation in treatment was instituted as compared with the preceding year other than the conditions under which this man's work was done. We are not so certain, however, that these lighting conditions would have produced the train of effect which they evidently did if his nervous equilibrium and poise had been normal. However, it is the privilege and the duty of the examiner to trace out the main and auxiliary factors in every case and to strike for the elimination of, or the partial alleviation of, the causes contributing to the impaired ocular efficiency of his patient. Paresis and Paralysis of Accommodation Due to Syphilis If we pass from acute infectious diseases such as diphtheria, typhoid fever, recurrent typhus, articular rheumatism, et al., which may make themselves felt in the ciliary muscle, to chronic constitutional changes, we meet first of all syphilis, "that uni- versal cause of all the'pathological lesions imaginable." (Landolt.) Relative to it Bonders wrote, in 1864: "Only syphilis is recog- nized as a constitutional cause and, if mercurials are used, it may produce paralysis even many years after infection. In such cases the paralysis is rarely limited to the accommodation. The seat is especially considered to be central, when both sides are affected; by periosteitis, by peculiar tumors of the nerves, perhaps also by inflammation of the nerves, syphilis may produce paralysis." Its injurious action on the apparatus of accommodation may arise either from a lesion of the centers of the common oculo- motorius or, perhaps oftener, from the compression or destruc- tion of the fibers of this nerve by an infiltration of its sheath. Alexander {Berl. klin. IVoch., No. 21, 1878 and 'Deutsch, med. IFochcnschr., 1881) found a unilateral paralysis of the ciliary muscle in cortical syphilitic affection of the brain. Hutchinson {Medico-Chirurg. Trans. ^ Vol. LXI and Med. Times and Gazette, 1878) collected several instances of paresis limited to a single eye and attributable to a more peripheral lesion, that of the ciliary ganglion. Isolated paralysis of the muscles of accommo- dation and of the iris only, or internal ophthalmoplegia, maybe found and is nearly always of specific origin. However, as Howe {Muscles oj the Eye, Vol. II, page 271) remarks, it was formerly customary to think that almost all of the ocular paralyses were of specific origin, either in the inherited or acquired form. Fournier, for instance, says that at least seventy-five per cent, of the ocular paralyses are due to specific infection. To these C( nclusions Howe objects and says : "It is probable that these statements give an exaggerated idea and that they are based upon general impressions." Course No. 14 Page 70 Paresis and Paralysis of Accommodation in Locomotor Ataxia Paraylses of accommodation are rare symptoms in tabes without the accompaniment of paralysis of the sphincter pupillae. Cases have been reported in which the pupil was normal but in which (in one eye usually) there was in addition to the paralysis ot accommodation a loss of sensation in the skin around the orbit. Later stages rather than the initial periods of tabes generally evidence ciliary paralysis. Paralysis of Accommodation Induced by Chronic ^Infection of the Faucial Tonsils C. A. Veasey in an article in the Ophthalmic Record^' yo\. XXV, 1916, records two cases of chronic infection of the faucial tonsils as a causative factor in the production of paralysis of accommodation. He points out the role of focal infections in the production of various diseases. The tonsils (both faucial and pharyngial), the teeth and the accessory nasal sinuses have been particularly active as foci of infection. Paralysis of Accommodation Due to Traumatism We need simply note the fact that injuries through blows, especially those received in childhood, may be the cause of a marked paralysis of accommodation. In many of these cases, however, a considerable refractive error is present, and adequate refractive corrections, coupled with sufficient additional con- vex lens power, may enable such an eye to engage in the act of vision and it may be taught to function with fair success. Accommodative Disorders in Hysteria Hysteria plays an important part in the pathology of the nervous system. For years hysteria was regarded as an affec- tion confined almost wholly to the fair sex. In fact many women do suffer from nervous affections, neurasthenia and other con- ditions bordering upon hysteria and many are found who exhibit many of the symptoms of what may be properly called hysteria. When we consider the natural aversion which so many women possess to the wearing of glasses and the untold suffering many of them will endure rather than sacrifice their false sense of beauty of face or features to that which they seem to believe will mar them or "age" them but which would, in untold instances, afford relief, we are not surprised that neurasthenia, due largely if not entirely to uncorrected errors of refraction and disorders of the motility, has become a matter of common knowledge to ocular practitioners. Perhaps no one in this country has done more in the calling of our attention to the effects of uncor- rected errors of refraction and disorders of the motor apparatus upon the nervous system than has Dr. George M. Gould in his Biographic Clinics. The discussion of hysteria and neurasthenia Course No. 14 Page 71 by Dr. Ambrose Ranney in his Lectures on Nervous Diseases, and the cases cited of ocular disturbances and their bearing upon these affections are classics. Probably the most compre- hensive treatment of this subject is that given by Dr. M. Parinaud on "The Ocular Manifestations of Hysteria," translated by Dr. Casey A. Wood, which forms a part of Xorris and Oliver's System of Diseases of the Eye. The disorders of the accommodation are the^most frequent of all the hysterical (neurasthenic) affections in general. It is quite common in children to find such disorders of the accom- modation as the earliest evidences and manifestations of the neurotic condition. Painful Accommodation The subject of painful accommodation is closely allied with that of accommodative anomalies associated with nervous derangements. In fact the differentiation into the two groups is not, at present, clearly defined. Donders, in the closing para- graphs of his epoch-making book 0?2 the Accommodation and Refraction of the Eye, discusses spasms of accommodation and painful accommodation. Recently Dr. John Green of St. Louis has discussed this topic {American Journal of Ophthalmology, Vol. I, 191 8) and cites in detail three cases. The personal history in each case evidences the fact of overwork, or excessive nervous strain, or the strenuosity of making a way in the world. Green says in conclusion: "I am convinced that there is always a background of physical or mental stress (or both), eventuating, finally, in some form of nervous instability. The painful irri- tation of the ciliary may be the sole expression of the neuras- thenic state, or it may be but one symptom added to a multiple of other signs of nervous instability." Spasms of the Accommodation or Excessive Accommodation A spasm of the accommodation may be either clonic or tonic. In clonic spasms, the condition is produced only under the influence of fixation, convergence, a desire for clear and distinct vision and by various causes which excite the sensibility of the eye, such as excessive illumination. The clonic spasm ceases as soon as the eye is in repose and at rest. In tonic spasms, the ciliary cramp and abnormality of tension of the lens are per- manent and do not readily yield to treatment; the repeated instillation of mydriatics in many cases appears non-efficacious. Clonic Spasm. The commonest form of spasm of accom- modation is that which tends to increase the refraction of nearly all young persons and makes it appear less hyperopic and more myopic than it is in reality. This spasmodic contraction of the ciliary muscle is, in most cases, inoffensive, since there are good reasons for believing that there should be a slight physiological tonus of muscles, the ciliary included. As a result, all objective Course No. 14 Page 72 tests, when properly carried out, will normally indicate and give evidence ot a higher hyperopic or lesser myopic correc- tions than will the monocular subjective tests. This spasmodic contraction of the ciliary muscle ceases with fixation. Hence, in our objective tests we should see to it that the stimulus to relaxation is the greatest possible by having the object passively observed; this can be accomplished by having the object looked at as far as possible from the eye under test, or, better still, by having it gaze vacantly into space. When this physiological tonus is excessive, however, or is abnormal, there may then arise serious conditions of asthenopia and it may play a part in the actual production of myopia. It is, of course, possible that an abnormal contracture oi the ciliary muscle may produce an apparent regular astigmatism or conceal a genuine one. There- fore, it behooves all practitioners to make careful retinoscopic examinations by both static and dynamic methods, and to give greater weight to these various objective findings than to the responses of the patient as to his ability to see various chart letters, whether this patient be previously or subsequently under a lenticular or cycloplegic suppression. In the simple forms of accommodative spasms the pupil usually presents nothing of special interest. It generally reacts normally in all particulars. Its diameter is not affected by the contraction of the ciliary muscle. The only evidence of its presence from the objective standpoint is obtained from either retinoscopic or ophthal- moscopic measurements of the refractive condition. Tonic Spasm. In tonic spasms, however, we are dealing with more serious and pronounced physiological effects. There is a diminution in the amplitude of accommodation accom- panying such a spasm. However, it can be readily differentiated from the diminution produced by paresis since, in the former case, the pupil is rather restricted, while in paresis it is dilated. Persons subject to such tonic spasms generally complain of disagreeable sensations of constriction in the eye or eyes. This sensation is often accompanied with a feeling of discomfort and a nagging irritation in the entire orbit or region of the eyeball. A hypersecretion of tears is often observable when the spasm is due to an irritation of the sensory nerves of the eye. The acute- ness of vision is generally below normal, which is the keynote. Again, there may exist a strong tendency to convergence which may amount to a genuine strabismus; this problem, however, is one which depends for its solution upon the determination of the actual relationship between the accommodation and the convergence as supplied in conjunction with the act of accommo- dation. Again, there may be conditions of actual excessive accom- modation and of relative excessive accommodation. In the first of these (/". e., actual) we shall find that the near-point is abnormally close and that it can be made to recede permanently Course No. 14 Page 73 by the use of lenses, or, in extreme cases, by the use of cyclo- piegics. In relative excessive accommodation we find that the near point is at a normal distance for the age of the person and that It cannot be made to recede permanently by the use of glasses or cycloplegics. Frequency of Actual Excessive Accommodatioyi. Upon the topic of the frequency of spasms of accommodation we find many and somewhat conflicting opinions. Possibly Lucien Howe, M. D., has given us a very fair and well-balanced statement. He writes {Muscles of the Eye, Vol. H, page 25): — "The large majority of the modern writers agree that some spasm of the accommodation is decidedly common, especially in school children. Thus Stocker found it in five per cent, and Schmidt-Rimpler in from ten to thirty per cent., according to the refraction. Among myopic children this condition is appar- ently even more frequent. . . Not unfrequently, when the test case shows a higher degree of myopia than the ophthal- moscope, if atropin is prescribed we find that the apparent myopia disappears in part. . . . It is no unusual exper- ience to obtain then as good vision with a decidedly weaker concave or stronger convex glass, and very often with at least partial relief of any symptoms of discomfort. It is true that sources of error must be taken into account. Measurements made with the ophthalmoscope only are not altogether reliable. With subjective tests, especially among children, the replies are contradictory; such patients are often emotional, notional or hysterical, and, above all, the term "spasm" of accommo- dation, as generally used, is too restricted. For that reason we must be careful in accepting statistics on this point unless all the details are fully stated. But in view of the facts before us, we must conclude that while the slight degrees are doubtless common, at least among school children, and especially among those who are myopic, the moderate degrees, and certainly those which are severe, are rare." We find in our practice many cases in which minus cylinders with axes approximately horizontal have been prescribed, whereas plus cylinders at the opposite axes are actually needed, as indicated by all scientific tests exclusive of the very unscien- tific test of reading letters. The question is, therefore, one of spherical correction, since the transposition of minus cylinders into plus cylinders at opposite axes involves the addition of the corresponding convex sphere. The ocular problem is, then, that of properly ministering to the accommodative needs. Funda- mentally we ought not to speak of such cases as "spasms of accommodation;" yet they should be grouped in a class very closely allied to those of spasm. A better term would be, there- fore, as suggested by Lucien Howe, "actual excessive accorn- modation." Every practitioner has the chlorotic or neurotic Course No. 14 Page 74 type of woman or the overworked and nervously drained man who comes with a history of reflex symptoms and distractions, such as headaches, pains in the eyeballs, excessive lacrimation and so forth. He or she may likewise be wearing from —0.25 to —0.75 or —I cylinder axis approximately horizontal. Care- fully conducted objective tests with static and dynamic ski- ametry, tonicity and duction tests, accommodative tests and convergence reserves may clearly indicate that convex cylinders, with axes vertical, are needed. Possibly the patient will refuse them, since the abnormal functionings ot a pair of eyes cannot be remedied in a few hours. Rest and the refraining from close work; sleep, exercise and simple food, coupled with the maximum approximation to the lens assistance which is scientifically indicated will, in the end, probably remedy the troubles. Symptoms (i) The range of accommodation is not normal. The near- point is too close to the eye for the age of the person under test. The far point also may be approached; that is, there may be an apparent and not real myopia. When the visual acuity is tested out, the patient may not be able to read 20/20, but can do so with a concave lens, usually a very low or weak one. It is entirely possible that such eyes are either emmetropic or slightly hyperopic. The writer has often said in his public utterances that the Devil himself has impressed his personality upon and left his touch upon the trial case when he had inserted therein the —0.25 spheres and the —0.25 cylinders, more particularly the former. More minus spheres of this low amount and almost as 'many simple minus cylinders instead of plus cylinders at opposite axes (usually at or near the 90° point) are improperly prescribed than the average reader may imagine and a con- siderable number of us spend a goodly portion of our time undoing these violations against the laws of scientific refraction. We feel so strongly upon this point that we have come to consider the presence of the minus quarter spheres as veritable poison, to be handled with care. Certain it is that low degrees of spasm would be corrected on purely visual acuity tests by low minus lenses when objective methods and various muscle tests indi- cate the contrary. The chief indicators and methods which are available in order to avoid these egregious blunders lie in: — (i) The history of the case, the presence or absence of asthen- opic symptoms; (2) the scientific use of the fogging system or of cycloplegics if such is the choice of the operator; (3) care- ful obtainance of full static and dynamic skiametric findings, and (4) a careful investigation of all the accommodative and convergence relations and resources. (2) The relative accommodation is altered. The positive part, obtained by the use of minus lenses, is increased. With convergence at thirteen to ten inches, the minus lens which can be overcome is stronuer than usual. In turn, the negative part Course No. 14 Page 75 of the relative accommodation is abnormally small. With parallel axes the patient may even require a concave lens to see clearly. To illustrate: If for a certain age the average positive relative accommodation at thirteen inches is 2D and the negative is 1.5 D and a certain case shows a positive relative accommo- dation of 4D and a negative accommodation of 0.5D we should suspect a condition of spasm. (3) IVrinkling of the forehead. Efforts of the ciliary muscle accompanying excessive accommodation or which are directly or indirectly the result of insufficient accommodation call into action the accessory muscles and there often results a scowling or wrinkling of the forehead which is reasonably characteristic of the condition. When any cause contributes to produce a contraction of the accessory muscles of the forehead there results a facial expression which is quite diagnostic. When this affects chiefly the muscles involved in accommodation it is found that the wrinkles are, for the most part, vertical; starting from the root of the nose they pass directly upward or may radiate from that point upward and outward in a fanlike manner. The most important of the subjective symptoms include: (i) Sudden variability in vision in reading the test-letters for distant vision. For instance, in testing monocularly the patient may read all of the letters down to and including V = 20 '20, when suddenly the letters fade out and the patient is not able to read more than 20/70 to 20 100 and sometimes not as well. If the patient is allowed to sit quietly with eyes closed and the test is repeated, the same performances will likely occur. The reason is obviously that this sudden failure of vision is due to sudden contracture or spasm of the ciliary muscle, which allows the crystalline lens to change shape and there is temporarily created a false, or spasmodic, or similated myopia. (2) Change ableriess and varying intensities or clearness of the lines on the fan or clock-dial chart. This method of testing subjectively for astigmatism has been called into question by many practitioners. Essentially, however, the method is good and proper, but the operator must remember that astigmatism implies an interval of Sturm and that sufficient fog must be employed to suppress accommodation and erratic or spasmodic changes of the crystalline lens, and yet, on the other hand, vision must be sufficiently keen to enable the observer to be aware of slight differences in various groups of lines. In the spasm of accommodation, for example, the patient may report the horizontal lines as blackest or plainest at one instant and a moment later report that the verticals are clearest. Evi- dently, in such a case, the ciliary spasm has changed the hyper- opic astigmatism into myopic astigmatism. The correct pro- cedure is then to carefully "fog out" the case. Course No. 14 Page 76 (3) There is often a decided sense of contraction or drawing in the eyeball itself or immediately surrounding it. This is, of course, the physiological reaction of an abnormal condition of contracture of muscles. (4) The variability of the correctin;^ glasses accepted by the patient. Certain it is that our monocular findings subjectively vary considerably from our retinoscopic findings in many cases. Binocularly, however, a closer approach may be made, since a binocular crowding on of plus lenses is often possible. The objective symptoms of spasm of accommodation include: (i) When the ophthalmoscopic examination shows the refractive condition of the eye to be considerably different from the glasses accepted on subjective testing. For example, suppose the patient accepted +1.5 D. S. and the ophthalmoscope shows him to be a hyperope of 5 to 6 D. Or again, subjectively he may have accepted a — i D. S. when the ophthalmoscope indicates + 1 D. S. Quite frequently a patient will relax his spasm of accommodation under an ophthalmoscopic examination when he will not under subjective testings. This is because there is little or no stimulation to accommodation and because the examination is generally conducted in quite a dark room. (2) The retinoscope may show decided variations in the refractive conditions, possibly indicating hyperopia one instant and myopia the next. The maximum plus or minimum minus correction thus obtained afi-'ords a fairly scientific measure of the correct refractive assistance needed. (3) In cases of astigmatism, when the amount of astig- matism subjectively found varies widely from the ophthal- mometric findings, one may suspect a spasm of accommodation. References 1. American Encyclopedia of Ophthalmology. Especially the section on the Refraction of the Eye. 2. Cress. The Theory and Practice of Dynamic Skiametry. 3. Bonders. Accomtnodation and Refraction of the E\e. 4. Howe. The Muscles of the Eye. 5. Laurance. Visual Optics. 6. Norris and Oliver. Syston of Diseases of the E\e. Vol. IV. 7. Savage. Ocular Myology. 8. Sheard. Physiological Optics. Dynamic Skiametry. Dynamic Ocular Tests. 9. Tscherning. 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