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A study of the effect of cycloplegia-mydriasis on the parameters of latent ocular nystagmus is reported. Cyclopentolate 1% (Cyclogyl) appears to decrease the amplitude, velocity, and, to a lesser extent, frequency of latent ocular nystagmus in a majority of the cases studied. This was associated with improvement in the monocularly recorded visual acuity. The interaction of latent nystagmus with manifest nystagmus, gaze nystagmus, and opticokinetic nystagmus, and their modification by cycloplegia indicated that separate neurologic centers are operative, and one may dominate another under different conditions. Possible explanations of the effect of the drug on nystagmus are discussed in relation to current theories of the etiology of latent nystagmus.

The occurrence of abnormal ocular development in generalized mesodermal disorders such as arachnodactyly (Marfan's syndrome, dolichostenomelia) has been recognized for some time. More recently, characteristic alterations in the chamber angle in this condition1-3 and in other mesodermal disorders such as idiopathic scoliosis have been described.4 A generalized mesodermal disorder, closely resembling Marfan's syndrome in the human can be produced in rodents by feeding the young a diet containing a high percentage of lathyrus odoratus seeds or their active principles. This diet-induced disease state called lathyrism includes scoliosis, deformities of the extremities, and dissecting aneurysm of the aorta. Extensive studies of this experimental mesodermal disorder have been done by Ponseti and his co-workers who, in addition to describing in detail the gross changes, have explored the histochemistry of the abnormal tissues, and have isolated the principal active compound from the lathyrus pea, β-aminopropinonitrile.5,6 A closely related compound, aminoacetonitrile,

In 1941 Georgiana Dvorak-Theobald1 published a study of the histologic eye findings in arachnodactyly and in 1954 Reeh and Lehman2 presented a clinicopathologic case report on the eyes of a patient with such a condition. Most recently Sadí de Buen and Velázquez3 have added a third case to this series.We were impressed with the remarkable developmental anomalies in the chamber angles of the eyes of these patients and suspected that chamber angle changes might be a regular occurrence in patients with arachnodactyly. Gonioscopic studies in patients with Marfan's syndrome have confirmed this suspicion (Burian4). They have now been discussed in more detail by von Noorden and Schultz.5Drs. Theobald, Reeh, and de Buen have very kindly given us slides of their cases for study and allowed us to use them in this publication. Their descriptions of the chamber angles are excellent, but they are

In the textbook descriptions of the jaw winking phenomenon of Marcus Gunn, it is sometimes stated that the phenomenon affects only one eye. This is not entirely correct. Though it is unilateral in the vast majority of cases, 7 cases have been reported in which it was bilateral.1-7The jaw winking phenomenon may be combined with anomalies of the extraocular muscles, in addition to the ptosis of the upper lid, which was found to be absent in only 7 or 8 cases recorded in the literature. Congenital paralysis of the homolateral elevators is frequently observed; occasionally there is a paresis or paralysis of other extraocular muscles or even an external ophthalmoplegia. In a few scattered instances, miosis of the homolateral pupil, Horner's syndrome, miosis of the contralateral pupil, and coloboma of the iris have been described in association with the jaw winking phenomenon. However, a careful search of the

A brief flash of light following a tachistoscopic stimulus containing information to be perceived will obliterate perception of the information under certain conditions. The information will be either correctly perceived, or partially or completely eliminated from perception, depending upon the time interval between informative and blanking flash and on the intensity of either flash. The critical time interval at which the blanking flash does no longer interfere with perception of the information delivered by the first flash has been termed "perception time." The process of extinguishing information by interference of a subsequent light stimulus is known as "perceptual blanking."1,2Extensive work on perception and the conditions on which it is dependent has been done many years ago by Helmholtz.3 On the basis of Helmholtz's work on stimulus duration and perception, Exner4 measured the time interval at which a strong light interferes with perception of a preceding weak

In descriptions of the chamber angle of normal eyes, i.e., of eyes free from glaucoma, inflammatory conditions, and gross developmental anomalies, certain features are included which are considered to be normal variants. Among them are variations in appearance and insertion of the root of the iris, iris processes, bridging pectinate fibers, variations in the appearance of the surface of the ciliary body band, and prominence of the ring of Schwalbe. For example, François1,2 has reported how frequently he has encountered these different features in his series of normal eyes.In general, they are of no obvious significance with respect to the functioning of the eyes. This is the justification for considering them to be normal variants. But the label "normal variant" does not tell us in itself anything about their nature and origin. No attempt has been made thus far to explain their presence in, or absence from, the

In a recent paper it was reported by Burian, Braley, and Allen1 that the trabecular zone is externally visible by slit-lamp biomicroscopy in all normal eyes and that a thickening and prominence at the edge of this trabecular zone on the chamber side, constituting the so-called embryotoxon corneae posterius, is a relatively frequent occurrence. In no patient seen up to the time of publication of that paper could the region of the canal of Schlemm be identified in external examination. Ascher2 had previously described a patient in whom the canal of Schlemm was visible owing to a coloboma of the corneoscleral limbus, but this case had remained unique. In the present paper we wish to report on two patients in whom we were able to observe the region of the canal of Schlemm by external slit-lamp examination and in whom we could verify this finding by gonioscopy. The

INTRODUCTION Investigations into the nature of amblyopia ex anopsia and into the behavior of the amblyopic eye have aroused renewed interest during recent years. In 1952 Brock and Givner,1 and somewhat later Jaffe and Brock,2 reported on a test by means of which they attempted to show that many amblyopic eyes fixated eccentrically. This work has been widely cited, and some rather far-reaching conclusions have been drawn from it (Linksz3). However, to our knowledge no one has troubled actually to repeat this test and to determine its validity or limitations. We have, therefore, undertaken to do this and are presenting our findings in this paper. METHODS AND CLINICAL MATERIAL The test of Brock and Givner applies to patients with amblyopia the well-known fact that an after-image, produced in one eye, can be accurately localized by most subjects when the exposed eye is occluded and the contralateral, unexposed

IN RESPONDING to the high distinction of being selected to deliver the Fourth Annual John E. Weeks Memorial Lecture, I have chosen a topic which may seem somewhat remote from the field of endeavor of the man whose memory we are honoring tonight. When John E. Weeks was a forward-looking young man, his keen mind turned to bacteriology, the new and exciting field of his day, with the result that his name has become linked with that of the great Koch. And thus his name is best remembered and known to ophthalmologists the world over. Yet those who were more closely associated with him knew that his curiosity was not limited and that he took a broad interest in the advancement of ophthalmology, a specialty so universal that there is hardly a medical or scientific discipline upon which it does not touch. With this thought in mind I shall talk

WHENEVER a light stimulus is thrown upon a functioning retina, a typical, reproducible action current can be obtained. Until recently the electric responses of the retina to light stimulation have been used almost exclusively as a tool for the study of retinal physiology in animals. Improved methods of derivation of retinal action currents and other methodologic improvements have made it possible to extend this study also to the human electroretinogram. In the past few years this method of investigating retinal function has gained increasing attention among ophthalmologists in the hope that it may contribute toward the understanding and solution of clinical problems.The electroretinogram is a complicated polyphasic response which varies in its properties with the intensity, size, duration, and wave length of the stimulus and with the state of adaptation of the stimulated retina. When stimuli of short duration are employed, the normal electroretinogram consists mainly of a small,

STATEMENT OF THE PROBLEM AMBLYOPIA ex anopsia and the closely related phenomenon of suppression present problems which extend beyond purely ophthalmologic interest. In amblyopia and in suppression there has been provided a "natural" experimental situation in which a tissue showing no discernible pathologic change is affected by a reversible inhibition of its function.Inhibition of function is a general property of the nervous system. In the case of more or less transient suppression of central vision in one eye and in amblyopia ex anopsia, a situation obtains in which one aspect of the inhibitory process is readily accessible to investigation in the intact human organism.Some authors believe that the seat of the inhibition in amblyopia ex anopsia is in the retinal neurons; others are of the opinion that the seat is in the central nervous system. We incline toward the latter view, since a study of the dark-adaptation process

THE DARTMOUTH Eye Institute, of Hanover, N. H., has closed its doors. A unique institution has passed from the scene of American ophthalmology. It is worth while looking at its history.The origin of what in 1937 became the Dartmouth Eye Institute dates back to 1919. In that year Adelbert Ames Jr. came to Hanover, N. H., to join with Prof. Charles Proctor, of the department of physics of Dartmouth College, in carrying out research on the optical properties of the human eye.Ames is neither an ophthalmologist nor a physicist. Trained as a lawyer, he abandoned law to become an artist. Being of an analytic as well as artistic temperament, he soon became interested in the question of the relation of what one sees to what is represented on the canvas. The pursuit of this problem led to the question how the organ of sight reproduces the environment. In

V. ORIGIN OF ANOMALOUS CORRESPONDENCE Nothing is known about the mechanism which brings about the loosening of the normal sensorial relationship and the revaluation of the spatial values of the retina of the deviated eye. For the time being, one is entirely dependent on speculation in this matter. However, any consideration of the problem must take account of the following facts : (a) Anomalous correspondence may be observed even in cases of extreme amblyopia of the deviated eye, and (b) it is the prolonged simultaneous stimulation of the fovea of one eye and of an eccentric element of the retina of the other eye that leads in some way to the establishment of anomalous correspondence.Deeply rooted anomalous correspondence may be observed in cases of extreme amblyopia. For instance, I have seen a student with a congenital, partly absorbed cataract. After this cataract was removed by needling, vision in that eye—in

When a meridional size lens1 is placed with its axis in the vertical position (at 90 degrees) in front of one eye of a normal observer, the retinal image of that eye is enlarged in the horizontal meridian. Since horizontal disparity of the retinal images is responsible for stereoscopic effects, the observer will experience typical changes in the appearance of his environment. If the size lens is placed in front of the right eye, objects located in the right half of the observer's field of vision appear larger yet farther away from him than objects of the same size situated at the same distances from the observer but located in the left half of his field of vision. A flat desk top will appear to be slanting down on the right side and slanting up on the left side ; a wall perpendicular to the observer's line of gaze will

I. INTRODUCTION AND DEFINITIONS The two eyes are never identical. Between them there are always numerous discrepancies in the neuromuscular apparatus, the dioptric system and the sensorial apparatus. The discrepancies of the neuromuscular apparatus, the heterophorias, cause a faulty relative position of the eyes when fusion is suspended. The aberrations and other irregularities of the dioptric system cause faulty dioptric images, which in some cases may differ considerably in the two eyes. Furthermore, the differences in the relative position of objects in space and in their distance from the two eyes cause geometrically different images to be formed in the two eyes. The discrepancies of the sensorial apparatus are caused by a special distribution of the receptor elements.As a result of all these discrepancies and incongruities, the two ocular images1 of the visual system are different even under normal conditions. The incongruities as a rule are overcome by

Up to this time all investigations concerning the fusion of identical objects have been conducted with stimuli which had a simultaneous effect on the fovea of one eye and on certain surrounding areas located near the fovea of the other eye. Previously, no attempt had been made to learn how identical objects imaged on strictly peripheral disparate points of the retinas can affect the relative position of the two eyes.For an investigation of this kind a haploscope, such as Bielschowsky and Hofmann used in their fundamental work on fusion, is inadequate. One needs an instrument which permits the stimulation of any desired areas of the two retinas with identical stimuli, the relative position, size, shape and brightness of which can be controlled.An arrangement of several projection lanterns and polarizing material, which allows the dissociation of the two eyes, fulfils these conditions and has proved to be satisfactory.Two

One hundred consecutive patients with heterotropia were tested for the state of their retinal correspondence with a major amblyoscope, the striated lenses, and the after-image test. Of this group 84 responded with anomalous retinal correspondence (ARC) on the major amblyoscope, 50 had some form of ARC with the striated lenses, and 36 had some ARC with the after images. This evidence is interpreted in the classical fashion that the difference in response is due to the fact that the major amblyoscope test more nearly duplicates the conditions of casual seeing than does the after-image test. The data are analyzed also with regard to occurrence of ARC in patients with a deviation of 30Δ or less and with a deviation of more than 30Δ the prevalence of suppression, and of unharmonious ARC on the major amblyoscope.

The problem of the pathophysiology of strabismic amblyopia may be approached from a number of points of view. Since this type of amblyopia is characterized by the absence of ophthalmoscopically demonstrable organic pathologic defects in the retina, many investigators have considered that the decrease in visual acuity results from an active inhibition in the visual cortex. Others have placed the seat of the inhibitory process in the retina itself. Still others have felt that in strabismic amblyopia there is a disturbance of the higher visual functions which results in an inability to integrate a sensed form into a meaningful percept. vom Hofe1 in 1930 first hinted at this possibility. Testing the visual acuity of amblyopic eyes with various simple geometric forms (rectangle, cross, circle, etc.), he reported that the responses of some of his patients were reminiscent of the behavior of the patients with traumatic lesions of the occipital

In the first part of this study1 we reported on the influence of a neutral-density filter on the visual acuity of patients with normal eyes, with strabismic amblyopia, and with organic retinal damage. The present, second, part deals with the visual acuity at different levels of illumination of three similar groups of patients. MATERIAL AND PROCEDURE Ten eyes with central fixation and strabismic amblyopia, ranging in visual acuity from 5/6 to 5/15 with single optotypes; ten eyes with amblyopia due to pathologic fundus lesions, such as diabetic retinopathy and macular edema, and ten eyes with normal visual acuity were examined.Prior to the test the patients were kept for 10 minutes in a completely darkened room. Single optotypes (black letter "E" on white ground) were then presented at 5 meters distance. The optotypes were shown to the patients in an evenly illuminated box. The illumination was controlled

The spectral sensitivity of the human eye depends upon the sensitivity of the retinal elements. However, in the intact human eye the composition of the radiant energy reaching the retina is such that its sensitivity in the violet and near ultraviolet can not be evaluated fully by psychophysical methods. Owing to the absorption of the near ultraviolet by the yellow crystalline lens, which has a rather sharp cut-off at 400 mμ, ultraviolet radiation generally reaches the retina only in minimal quantities.In one of his most remarkable papers. Wald1 has shown, among other things, that with the removal of the lens the eye gains enormously in sensitivity in the violet and ultraviolet. Whereas in the intact human eye the sensitivity of the fovea declines at 365 mμ to 1/40,000 of its maximal value at 562 mμ, aphakic rod-and-cone vision is still about 1/30 as sensitive at 365 mμ as

INTRODUCTION During the year 1956 there appeared in the ophthalmic literature two reports concerned with toxic effects produced upon the retina by a new drug belonging to the group of so-called tranquilizers (Verrey,1 Goar and Fletcher2). The new drug, 3-chloro-10- [2-N-(methylpiperidyl)ethyl] phenothiazine, designated by its producer, Sandoz Pharmaceutical, as NP 207, was developed in an effort to reduce the systemic effects of chlorpromazine hydrochloride. This goal was, indeed, achieved, and the tranquilizing effect of NP 207 proved to be as good as, or better than, that of chlorpromazine, from which it was derived. However, it soon appeared that NP 207 caused very undesirable visual disturbances. Subjectively they expressed themselves in a more or less severe impairment of dark adaptation and in a loss of visual acuity. Objectively one found in the early stages a hyperemia of the disc and some edema of the retina and in the later

INTRODUCTION The question of whether and how the act of accommodation influences the level of the intraocular pressure has been investigated and discussed ever since the inception of scientific ophthalmology. In spite of this, the answers have remained equivocal. Yet, unequivocal answers would be helpful in deciding whether it is true, as some authors assume, that close work has a deleterious effect on the eyes of patients with early glaucoma or whether, as others think, close work by such patients should not be discouraged but, if anything, encouraged.The question of the effect of the act of accommodation on the level of the intraocular pressure has become particularly important in recent times with the introduction of tonography for the study of the fluid exchange in the eyes. If accommodation should influence the intraocular pressure in one way or another, this could be a factor which might significantly affect the tonogram

INTRODUCTION During the past two decades, but especially during the last 10 years, there has appeared in the literature an increasing number of articles and discussions dealing with the clinical results of the correction of unilateral aphakia with contact lenses.Certain findings of clinical interest emerge from the study of these reports. One impression is that aphakic eyes would seem to tolerate contact lenses better than eyes not operated on.1,9,11,20,21 Goar attributes this to a reduction in corneal sensitivity of the operated-on eyes. On the other hand, Constantine and McLean do not think that there is such a reduction in the corneal sensitivity of the eyes of their patients. If, instead, the better tolerance could be attributed to the fact that these patients received sufficient benefit from the wearing of contact lenses to increase their willingness to wear them, this might be considered a strong argument in favor of

THE PHENOMENON of monocular diplopia (or binocular triplopia) which is observed in some patients with concomitant strabismus consists essentially of the simultaneous localization of a single physical stimulus, reaching one eye, in two different subjective visual directions, one normal and one abnormal. As a consequence, patients who display this phenomenon have triplopia when observing with both eyes.Binocular triplopia is rare as a spontaneous occurrence.1 This is not surprising in view of the special conditions required for its appearance. Modern investigations with major amblyoscopes of patients with concomitant strabismus have shown, however, that one can relatively frequently elicit it artificially (Cass2). Indeed, Walraven3 has developed a special orthoptic technique for the treatment of anomalous correspondence which utilizes monocular diplopia as a starting point. The interest in this fascinating phenomenon has, therefore, increased considerably of late; it has been taken out of the realm of purely academic problems,

THIS review attempts to cover the literature on strabismus for the year 1950. Some articles are included which appeared prior to 1950 but did not come to the reviewer's attention until 1950. A few papers were not available in the original. Where this is the case, the source of reference is cited. ETIOLOGY AND SYMPTOMATOLOGY In view of the significance which is generally attributed to refractive errors in the causation of strabismus, a comparison of the refraction of strabismic eyes with that of nonstrabismic eyes is of importance. E. V. L. Brown1 has made such a comparison, covering the period from birth to the 25th yr. on a year-by-year basis. His material consisted of 1,000 strabismic and 1,500 nonstrabismic eyes. The former presumably represent cases of convergent strabismus. Brown reached the following conclusions: The amount of hyperopia present in strabismic eyes in excess of that in the nonstrabismic eyes

WHEN I was invited to speak at this symposium, various topics came to my mind which might profitably be discussed. However, I discarded all specific topics, since it seemed to me that a topic of more general nature would be better suited to a joint gathering of orthopists and ophthalmologists.I am frequently asked what I really think of orthoptics. I have felt that this question should some time be answered in more elaborate form. This is why I am speaking tonight about the scope and limitations of orthoptics.Before considering its scope and limitations, one must first agree on a definition of orthoptics. In the broadest sense of the word, every form of nonsurgical treatment of neuromuscular anomalies of the eyes is orthoptic therapy. In this broadest sense the prescription of glasses for the normalization of the convergence-accommodation relationship is a form of orthoptic treatment. If this definition is

III. CLINICAL PICTURE OF ANOMALOUS RETINAL CORRESPONDENCE AND ITS INTERPRETATION The normal relationship between the two retinas, the normal retinal correspondence, is based anatomically on the interrelation between the cells of the sensory epithelium of the retinas and the cells of the visual sphere of the brain cortex. Ample experimental evidence has shown that the normal retinal relationship is physiologically fixed and that it cannot be altered in a subject with normal binocular vision. Yet anomalous correspondence does exist and can be observed daily in the practice of every ophthalmologist.How can this apparent contradiction be explained? The supporters of the so-called empiristic theory of space perception found an easy solution to this problem and, indeed, perceived one of the foundations of their doctrine in the fact that squinting persons are capable of acquiring a retinal relationship which differs from that of nonsquinters. They reasoned that the faculty of localizing

I. INTRODUCTION CORRESPONDING RETINAL ELEMENTS NORMAL AND ANOMALOUS RETINAL CORRESPONDENCE ALL VITAL manifestations in man have an objective and a subjective aspect. The interrelation of these two aspects represents one of the most complex problems of psychophysiology and philosophy. But the relation is accessible to a relatively simple analytic investigation when it is reduced to the basic sensory phenomena, as, for instance, in studying the act of vision. Such studies do not require the solution of the general problem—it this is at all soluble by rational methods—but, rather, form the basis for it.In the act of vision the "objective sphere," or "aspect," consists in (a) the object points in space and the wavelengths emitted or reflected by them (visual stimuli) and (b) the geometric optic properties of the refractive media of the eye, which determine the place and character of the dioptric image on the retina, and, furthermore,

Many patients experience difficulties in wearing astigmatic corrections. Primarily, asthenopic symptoms are reported, but annoying distortions of objects in space are also mentioned. As a rule, the spatial distortions disappear in a short time when the correction is worn constantly. The asthenopic symptoms, on the other hand, may persist and even be so severe as to force the patient to abandon the glasses altogether. This is particularly true when the axes of the required cylinders are oblique.The ocular discomfort has been attributed to the distortion of the retinal images produced by the cylindric spectacle lenses. These distortions have their principal effect in binocular vision. At an early date Wadsworth,1 Culbertson2 (who tried to correct the spatial distortion by rotating the cylinders) and Lippincott3 described some of the changes in the position and form of objects caused by astigmatic corrections. However, they did not explain the phenomena

I. INTRODUCTION 1. PHYSIOLOGIC BASIS OF BINOCULAR VISION Concomitant strabismus is never a purely mechanical anomaly. Innervational factors play a large part in its causation, and the faulty position of the eyes is always accompanied by a severe disturbance of the sensorial functions and the binocular cooperation of the eyes.1 It would be wrong, however, to assume that all sensorial cooperation between the two eyes ceases when manifest concomitant strabismus sets in. A more or less rudimentary sensorial cooperation can be demonstrated in all cases.The sensorial behavior of the eyes in normal and in anomalous conditions has been studied thoroughly, and there is today, a good general understanding of the visual act in squint. But many phases remain unexplained and many questions unanswered. The great biologic significance of the visual act in squint and its importance for the diagnosis and treatment in clinical cases warrant further investigation. At

It is relatively easy to observe the mechanical changes taking place during accommodation in the centrally located parts of the structures of the anterior segment of the eye. These changes have been carefully studied and form the basis of the various theories of accommodation. But such investigations could indicate only indirectly what, if any, specific changes were occurring in the peripheral parts of the structures involved, since direct observation was difficult or impossible with ordinary means of examination. Direct observations were possible only in cases of gross anatomic, and probably also functional, abnormalities, such as colobomas of the iris or aniridia. Even in these circumstances the chamber angle was not accessible to direct study. It is, however, of interest and importance to have a detailed knowledge of the behavior during accommodation of the periphery of the lens and iris and of the trabecular band, all of which are intimately concerned

EMBRYOLOGY In a previous paper1 it was shown that no tissue requiring atrophy and resorption is present in the typical chamber angle of the embryonic or fetal eye. A comparison of cell layer counts in fetal and adult eyes showed that there is on the average an increase in the number of cell layers between Schlemm's canal and the pigment epithelium of the ciliary body during the period of cleavage of the angle. The increase appears to be entirely within the ciliary-iris tissue. By contrast, the increase in size of the mass of trabecular tissue and the ring of Schwalbe seems to be due to cell growth and cavitation.To say that no tissue requiring atrophy is present in the average fetal angle does not mean that excessive tissue is not present in a certain percentage of cases. Excessive embryonic mesoderm is seen, but only approximately in the same

About two years ago our attention was drawn to glassy ring-like structures at the periphery of the posterior surface of the cornea. It soon became evident that these bands corresponded to the so-called posterior embryotoxon of the cornea (Embryotoxon corneae posterius, Axenfeld1), posterior marginal dysplasia of the cornea (Streiff2), congenital hyaline membranes on the posterior surface of the cornea (Mann3), or peripheral refractile postcorneal rim (Graves4). Once our interest in this subject was awakened, we devoted a close study to the limbus of all patients whom we saw and performed a slit-lamp gonioscopic examination on those who presented to external slitlamp study an unusual appearance of the limbus or of the periphery of the cornea.These clinical investigations were followed by a careful study of 600 pathologic specimens of eyes, and this study, in turn, prompted us to extend our investigations to the chamber angle of

In a previous paper1 we reported the identification of the embryotoxon corneae posterius, Axenfeld, or glassy-appearing membranes at the periphery of the posterior corneal surface, as the trabecular meshwork and the anterior border-ring of Schwalbe. In the cases available to us for complete study this identification was done through external and gonioscopic examination and by histologic diagnosis. Further assurance was gained by a careful histologic study of the chamber angle region of 600 eyes in our pathology collection. We also searched for new facts about the structure of the normal chamber angle to serve as basis for the interpretation of abnormal appearance in clinical cases. This led, in turn, to developmental and comparative anatomic investigation,* some of which will be reported here and some in a succeeding publication.2A new concept of the manner in which the chamber angle develops formulated itself as evidence from the separate studies

A case of macroglobulinemia with unusual fundus findings has recently been reported by Gates and Richards.1 This patient also presented severe electroretinographic changes which will be briefly described in this paper and compared to electroretinograms obtained from patients with various forms of anemia. REPORT OF CASES CASE 1 —Electroretinograms were done on the patient with macroglobulinemia on Feb. 9, 1960, on which date he had a hemoglobin concentration of 9 gm. %. The electroretinographic records from either eye were essentially the same. They showed with I1 stimuli * after 12 min. of dark adaptation only a small negative deflection. With I1 F1.30 there was no response after 18 min. of dark adaptation and the responses with I1 F0.7 and I1 were extremely low. They consisted essentially of slight responses of the photopic mechanism. The relative intactness of the photopic mechanism was evidenced also by the

An experimental model, using rabbits, for acute quinine toxicity is presented. Electroretinogram changes are shown to occur within minutes of the ingestion of 0.5 gm/kg. They consist of increase in a-wave negativity and b-wave depression, which return to normal within 24 hours. These changes should not be due to any action on the ganglion cell and call for a revision of current thinking on quinine toxicity.

Twenty rabbits received large doses of orally administered fluoride for 3 to 5 months. Baseline and subsequent electroretinogram (ERG) and ophthalmoscopic examinations were done on each rabbit as well as on a group of control rabbits. Although bone concentrations of fluoride were compatible with chronic system fluorosis, there were no significant differences in the ERGs, fundi, or microscopic sections of the treated eyes as compared to the control eyes.

In 1921, a study was reported by Ammann,1 in which the visual acuity of office patients was measured under ordinary conditions and with dark glasses, which, as the author stated, were of sufficient density to decrease the visual acuity for several lines on a reading chart. He found that the ratio between normal visual acuity and visual acuity with filter was as 1:0.3 to 1:0.5 in a group of normal patients. A group of amblyopic patients was examined in a similar manner, and the astonishing observation was made by Ammann that these eyes were not infrequently able to read the same line on the chart with and without filter.Our recent electro-ophthalmographic observations2 about the extraordinary capacities of eyes with squint amblyopia under reduced illumination stimulated us to do a similar study, not only because Ammann's work has to our knowledge never been repeated or confirmed but also

TO THE EDITOR: —The paper by Dr. Carl Kupfer in the December, 1962, issue of the Archives of Ophthalmology entitled "Relationship of Ciliary Body, Meridional Muscle, and Corneoscleral Trabecular Meshwork" again emphasizes the close relationship between the meridional portion of the ciliary muscle and the trabecular zone. He demonstrated beautifully that part of the trabecular meshwork represents, indeed, the tendon of that muscle.I find myself in full agreement with Dr. Kupfer in this respect. I must, however, take issue with the term "corneoscleral" which Dr. Kupfer attaches to this portion of the trabecular meshwork. As we have shown some time ago (Burian, H. M.; Braley, A. E.; and Allen, L.: Arch Ophthal 53:767, 1955) the division of the trabecular meshwork into corneoscleral and uveal portion, introduced by H. Virchow, is justified if one bases one's terminology upon the origin and insertion of the trabecular sheets. The corneoscleral lamellae arise

TO THE EDITOR. —Merton C. Flom, PhD, and Kenton E. Kerr, MOptom, have presented a paper "Determination of Retinal Correspondence" (Arch Ophthal77:200-213 [Feb] 1967) in which they challenge the view that the presence or absence of differences in the mode of localization in various tests for retinal correspondence (ARC) offers an indication of how thoroughly the ARC is established in a patient. The authors base their conclusion on elaborate statistical analyses which for all that remain unconvincing for a number of reasons.First, the group of subjects on whom they report is very heterogeneous. Included are 47 constant squinters (both esotropes and exotropes, the proportion is not given), 22 "occasional" (intermittent?) squinters, and 24 nonsquinters (presumably patients with heterophoria).Second, this inhomogeneity is the more disturbing since the groups are clinically ill defined. Patients who have to begin with a heterophoria have, by definition, normal correspondence. They

TO THE EDITOR. —The paper by Ralph Gunkel, PhD, "Retinal Profiles" (Archives77:22 [Jan] 1967), calls attention of the ophthalmologists to a very useful method in the study of retinal sensitivity. We have employed this method routinely for 15 years, using, as Dr. Gunkel does, a modification of the Goldmann-Weekers adaptometer. Our technique varies from Dr. Gunkel's method in that we prefer to use the horizontal retinal meridian rather than the vertical, and in that we use a two-degree test target instead of a six-minute one. For clinical applications this less critical target size has proven adequate, as may be seen from our various publications (eg, Archives60:612 [Oct] 1958; Amer J Ophth61:1044 [May] 1966).To gain a more complete picture of the retinal sensitivity we also employ the two-filter method with central fixation, following the course of dark adaptation. The two-degree test object is

TO THE EDITOR: —Intractable diplopia following operation on the extraocular muscles is discussed in a recent paper by George L. Tabor Jr. (Intractable Postoperative Diplopia, Arch. Ophth. 44: 517 [Oct.] 1950). Tabor has carefully sifted the literature and reported on a case of his own. His interesting study calls for comments on this important subject, which has received relatively little attention in the literature.One must define one's terms. Diplopia occurring immediately after operation, troublesome persistent diplopia and horror fusionis are not necessarily the same thing, although diplopia is common to all three.More or less transient diplopia after operation for squint is much more frequent than one should conclude from the statistics quoted by Tabor. As Krewson mentioned in his discussion of Tabor's paper, many patients experience transient diplopia while persistent diplopia is relatively rare. Transient diplopia is, in fact, rather the rule and occurs also in children, as

TO THE EDITOR: The letter of Dr. Joseph M. Dixon in the June 1966 issue of the Archives regarding the terminology of contact lenses calls for some amplification.The Greek verb haptein means "to fasten to; to fasten on." In its middle form it stands for "to fasten one's self to," hence "to cling to." Among the many secondary meanings are "to touch, affect; to apprehend with the senses, perceive," etc.The term "haptic" as it relates to contact lenses is not intended to convey the meaning that they cause a sensation of touch, or any other sensational meaning. The "scleral" contact lenses consist of two parts: a "haptic" portion by which they "cling to" the sclera and an "optical" portion positioned in front of the cornea. In the "corneal" contact lenses the scleral portion is dispensed with. A single element performs both the haptic and optic functions. Interpreted in

TO THE EDITOR: —If electroretinography has any place in clinical ophthalmology at all, then this place is surely in the differential diagnosis of the tapetoretinal degenerations. The knowledge in this field has recently been splendidly summarized by Franceschetti and Dieterle (Elektroretinographie, in Hamburg Symposium, Bibl. Ophth., Fasc. 48, Basel and New York, S. Karger, 1957). In this article it is made clear by many personal contributions of the authors that an extinguished electroretinogram is not only pathognomonic for chorioretinal abiotrophies but essential in establishing the correct diagnosis in difficult or doubtful cases.In view of this situation, it would be very significant if it could be shown that there are well-substantiated cases of retinitis pigmentosa in which there is an electroretinogram of normal shape, though possibly of reduced amplitude. Unfortunately, the case presented by Skeehan, Passmore, and Armington (A. M. A. Arch. Ophth. 57:536 [April] 1957) is not a well-substantiated

TO THE EDITOR: —We appreciate the opportunity of replying to the letter of Drs. Givner and Brock in the matter of the "transfer test" in amblyopic eyes.It was of interest to us to note that the authors agree that the status of the retinal correspondence is a limiting factor in their test, since this was not evident from their original publication.This is all the more important, because of the sweeping conclusion of the authors that "only about 20% of persons with uniocular amblyopia fixate along the central-foveal axis of the poor eye on occlusion of the good eye." Surely, such a conclusion cannot be drawn from a test which by its nature excludes a very large number of amblyopes.In view of this, it is not clear how Givner and Brock can claim that their tests were conducted on unselected amblyopes. We did not select our patients and

The author attempts to give within a limited space a survey, intended for the ophthalmologic practitioner, of the knowledge pertaining to concomitant strabismus. The fundamental physiologic concepts which, since set forth by Hering and Bielschowsky, have formed the basis for the understanding of the pathologic phenomena of squint, are touched on in a few sentences. The procedures to be followed in the examination of patients are then discussed, and the forms and causes of latent and manifest convergent, divergent and vertical strabismus are described. The author next lays down the principles of conservative and orthoptic treatment of these various forms and devotes the last chapter to the operative treatment of squint. Jameson's recession and Verhoeff's suture for advancement are mentioned.The value of this brief exposé is, necessarily, restricted. The presentation is too concise to be sufficiently detailed for any one not thoroughly familiar with this difficult subject; the beginner