sp)oken of as asthenopic troubles, and which werc due to some

MITTENDORF: Ocular Headaches. 339 FOUR THOUSAND CASES OF OCULAR HEAD- ACHES AND THE DIFFERENT STATES OF REFRACTION CONNECTED THEREWITH. BY DR. WV. F. AIITTENDORF, NEWV YORK. About four years ago I reported to the State Medical Society of New York the result of one tho'usand examinations of persons afflicted with headaches and other symptoms, which are usually sp)oken of as asthenopic troubles, and which werc due to some errors of refraction or disturbances of the musctular apparatus of the eyes. The favorable reception which this article received both from the members present and the medical press in general has encouraged me to continiue my observations, and, to-day, I propose to lay before you the results of the examination of three thousand (3,ooo) patients secn since the reading of the former paper. These patients camiie to me for the relief of asthenopic symptoms, and especially on accouint of headache. I havc not thougrht it bzst to include in this list those patients who came to me merely because they nieeded glasses on account of age or near-sightedncss, and in which there were no headaclhes or other asthenopic symptoms comp)lained of, and only those presbyopic or myopic cases in wvhich headache was a more or less prominent symptom are inicluded in this list. The purpose of the paper is simply to give the statistics of the differcnt refractive errors and their relative frequency, wlhich wvere at the bottom of the eye-strain leading to the manifestation of asthenopic symptoms and to hcadaches especially. The different states of refraction were as follows: OrIi.-6j

( $$ ' O~~~~~~~. I 2, 340* MITTENDORF: Ocular Headaches. Antimetropia, Myopia, Compound Myopic Astigmatism, is Simple " more than 0.5, { " " less than 0.5, ( Myopic, Astigmatism of, 0.5, is4 4 0.12,5 " with the rule. against "d Astigmatism oblique axis, Presbyopia. Hypermetropia. is with Presbyopia, Compound Hypermetropic Astigmatism, Simple " " " Astigmatism more than 0.5, 0.5 or less, 5" 5 with the rule, 0 against ".25 with " " 0.25 against" 1.2 with " 0.12 against" Hypermetropic Astigmatism oblique axis, Mixed " 103 105 213 226 III IIS 46 57 i8o 34 21 i88 499 223 265 I,978 391 1,587 482 105 687 120 24 12 138 126 Per cent. 2i 2+ 5+ 5+ 3 3 Ij 12 4+ I 40 12 I0 40 2+ 3 122+ I6i 3 31 3 In reviewing these figures some explanations are necessary. The most striking feature is, of course, the great frequency of the lower degrees of hypermetropic astigmatism. In speaking of the lower degrees I refer only to those cases where a cylindrical lens stronger than half a diopter was absolutely refused by the patient, but where a cylinder o.5 or 0.25, or even 0.12, gave perfect relief, and here we have the grand total of I,587 astigmatics of the 4,000 patients, whereas the number requiring more than a 0.5 cylinder was only 39I. It is somewhat surprising that patients with much higher degrees of astigmatism are, at times, apt to go through life without even complaining much of eye-strain, whereas so many eyes, in which there is only the slightest aberration of the normal curvature, should be troubled to such an extent as these statistics show. The reason of this is probably not only the greater frequency of the existence of slight degrees of astigmatism, but also the fact that persons with marked astigmatism have found out early in life that their eyes are weak, and that they must

MITTENDORF: Ocular Headaches. *341 take care of them, and they learn early to husband their strength, and thus they do not abuse their eyes as persons who imagine that their eyes are very strong are apt to do. On the other hand, persons with slight degrees of astigmatism are apt to have the most perfect vision for near and far. I have very frequently heard these patients remark that they do not know why their family physicians suspect that their eyes are at fault, when they can see as well as anybody else, and even a great deal better than many of their friends who are never troubled with headaches. Or patients will tell us that they think that their headaches are not due to eye-strain, but that they have inherited this tendency to headaches, as their father and grandfather have had similar attacks of headaches, forgetting, of course, that they, in all probability, inherited the parent's eyes, and that the defects of the father's eyes was not suspected to be the cause of headache complained of, and the error of refraction not being corrected or even recognized, they had to go through life with the headache unrelieved by the proper glasses, which, in the child, if properly used, will give perfect and prompt relief in most cases. Then, again, we meet with patients quite frequently who, perhaps, call on us on account of presbyopia or some disease of the eyes, in whom we discover quite a good deal of astigmatism; and, upon questioning them whether they had never experienced any unpleasant symptoms on using their eyes, they are apt to answer no; or they will answer, that knowing that their eyes were not very strong they would never read in the evening and otherwise take good care of their eyes. In regard to the weakest cylinder which I used, that of an eighth of one diopter, the fact that the number of it in these statistics is so small is due to the fact that I have used it only for the last six months. I was led to its employment by the inability to relieve some of my patients by either the weakest -concave cylinder in the one or the weakest convex cylinder in the. other meridian. I have seen such satisfactory results with it in some of these cases that I would not like to be without it now. In a great many of these cases the use of a cylindrical lens may not mean the permanent use of such a glass for near and for

342* MITTENDORF: Octlar Headachzes. far; in fact, in the majority of cases the use of such a glass for ncar work will be sufficient to relieve all the tinpleasant sy,mptoms; for one must not forget that astigmatism is in a great many cases inherited, and perhaps, in the majority of cases, congrenital; and that the patients have been able to do quitc an amount of work xvith their eyes without the slig,htest inconvenience for maniy years, until, from excessive use of the eyes, causingaatiriing of the muscle of accommodation or from some general debilitating cause, an insufficiency of the ciliary mutscle is produced, so that the astigmatism cannot be easily overcome by an accommodative effort, and that as a result of this weakening of the ciliary muscle the asthenopic symptoms, such as headaches, etc., becomc manifest. Now if by proper hygienic measures and especially by gymnastic exercises, rest of the eyes, and an -active outdoor life, the condition of the ciliary muscle is improved, the eye may for the rest of the patient's life perform its function in a most perfect manner wit hout causing any inconvenience whatever. However, it is not often possible to relieve our patients in such a way, and an accurate correction of the refractive error, and especially if this is of the astigmatic kind, becomes necessary. This is all the more necessary if it is not convenient to take the patient axvay from his work, for the cessation of or a break in the studies of a young person may have an injurious effect upon the whole future of the patient. In regard to the question of how long an astigmatic patient is to use his glasses I would like to answer that in a great many cases the glasses should be used only as long as the manifestation of unpleasant symptoms call for their use, and, in most of the cases, only as long as the eye is called upon to do any fine work. For instance, during the time I had been connected with our medical college I have sometimes had as many as ten or twelve students come to me quite discouraged because they could not use their eyes for more than a few minutes at the time, and fearing that they would have to give up their studies. Upon examining their eyes I would perhaps find a slight degree of astig,matism, prescribe for them the proper glasses, and they would be able to go through college -without any difficulty.

MITTENDORF: Ocular Headaches. 343 Meeting some of these doctors later in life and inquiring how they got along with their eyes after leaving college, they would very frequently tell me that they were soon able to leave the glasses off entirely, and that they had not used them at all for years. The reason-of this is that after leaving college their hunt after patients or the care of them after they found them would take them outdoors, and they would recover the power of accommodation, which enabled them to overcome the existent irregularity of the cornea without difficulty. It is for this reason that I allow my astigmatic patients, when their attendance at school is not necessary, for instance, during the summer vacations, to go without their glasses, provided they will promise me not to read much during this time, but live a healthy outdoor life as much as possible. I have likewise had occasion to observe that astigmatics doing a good deal of gymnastic work in schools or colleges will be able to do a moderate amount of studying without glasses and experience no inconvenience; but if the time for examination approaches and they devote most of their time to their books, they will soon become quite dependent upon their glasses. These are exactly the cases which, before we learned to recognize and appreciate the importance of the lower degrees of astigmatism and for which we had no lenses in our trial cases, we were obliged to take away from college or school and advised them to turn their energies into some other direction, such as farming or sheep-raising, for instance. Now I am happy to say we are able to relieve them and leave them at their studies. In fact, in young people, gymnastic exercises, good, but plain, diet, and a certain amount of exercise are nearly as important as the use of glasses. Mild stimulating tonic applications to forehead and temples will greatly add to the relief of the headaches, and acting as mild counter irritant may relieve the congested condition of the muscular apparatus of the eye. In regard to anisometropia I have included only such cases in this section where there was hypermetropia in one eye and myopia in the other eye. These cases Dr. H. D. Noyes has proposed to call antimetropia, and my experience is that some of them will cheerfully and comfortably use full correction for OPH.- 7

344 344 MITTENDORF: Ocular Headaches. both eyes, but still it is doubtful whether it is often possible to give these patients binocular vision; most of them will only accept correction for the eye which they are in the habit of using. Later in life they are apt to use the myopic eye for near work and the hypermetropic eye for the distance. Very often they are not aware of this fact, and it is sometimes amusing to convince them of this fact. I remember very well an old clerical gentleman who had one very myopic eye, which he supposed to be entirely blind, and who called to get a distance glass for his hypermetropic eye, which he thought he was using for near as well as for far. He accepted for this eye a 42 D. lens; when told to read he would do it without glasses by holding the book close up to his eyes. When I told him to close his supposed blind eye he could not see to read fine print, but, upon closing the hypermetropic eye, he saw, of course, the finest print with the highly myopic eye. The proportion of astigmatism with and against the rule does not, as I suppose, vary very much from other statistics, but I have been struck by the fact that in old people the astigmatism against the rule occurs much more frequently than in young persons, in fact, it is met with so often that it becomes almost the rule in old people to find the axis of the hypermetropic astigmatism at I800 and that of the myopic astigmatism at o. This is a fact which should not be overlooked in the selecnion of reading glasses for old people; for although in the majority ot cases a slight degree of astigmatism may be better overlooked, especially if strong convex lenses are required for reading, yet, in some cases the additional correction of the astigmatism, especially if it is against the rule, will give us a much better reading glass. The frequent occurrence of astigmatism against the rule in old people is undoubtedly due to senile changes in the lens and the frequency of its occurrence in such patients has been almost entirely overlooked in nearly all text-books on ophthalmology. The percentage of mixed astigmatism is perhaps a little higher in my statistics than we are accustomed to see them, and this requires a few words of explanation. Some patients with a high degree of astigmatism, where the other meridian is ap-

MITTENDORF: Ocular Headaches. 345 parently emmetropic, find the use of a strong cylindrical lens at times very trying, especially for distant vision. A very weak concave cylinder in the emmetropic meridian obviates this at once, and the patient is not only able to use the glasses better for the distance, but likewise for near work, and may even accept a stronger convex cylinder proportionately. I suppose the reason for this -is that the ciliary muscle, which has been used to an excessive amount of work before the correcting glass is used, cannot relax its fibres so promptly, and although increasing apparently the difference between the two meridians, yet allows some display of accommodation. The following two cases, which illustrate this, have been under my observation for some time, and have resisted all attempts to remove the concave lens for the opposite meridian, and although the vision is =20/xx with the plain convex cylinder, yet the addition of the concave glass makes vision much clearer both for far and near. Mr. L., merchant, 35 years of age, accepts C + 3 ax. go9 in each eye; he has been using his present glasses for nearly eight years with a C - 0.25 ax. I800 added. Miss W. of Boston, teacher, accepts C + I.5o ax. 900, which gives vision = 20/xx; but the sight is a little blurred, and an increase or decrease of the convex cylinder does not give such good results as A. C - 0.25 ax. I80 added; this gives clear vision and is much more agreeable to the eye, and relieves not only the headache, but other nervous symptoms which she had complained of. DISCUSSION. DR. H. D. NoYEs of New York. - I am quoted in this paper as the author of a new term for anisometropia. In I876 I prepared an article in which I advised the term anti-metropia to indicate that on one slde we had myopia and on the other hypermetropia, whether mixed with astigmatism or not. I do not know whether the author gave that definition. It merely means a division of aniso-metropia. DR. W. F. MITTENDORF. -Yes, sir. That is the way I used it. DR. F. BULLER of Montreal, Canada. - I would like to ask Dr. Mittendorf how he determines fractional parts of a diopter?

346 M1TTENDORF: Ocular Headaches. I think one rarely finds patients capable of distinguishing between an eight and quarter diopter. DR. W. F. MITTENDORF. -It is hardly possible with the ophthalmoscope, or Javal's instrument, to determine one-eighth of a diopter. If the patient finds that one-quarter diopter gives blurred vision and one-eighth does not, I prefer to order the latter. Very few persons require such a weak lens, but we do have such cases, nevertheless. I had a patient from the South -l few months ago who at first wore a plus one-quarter diopter cylinder axis ninety degrees, but, getting no relief went to another oculist in Atlanta, who ordered one-half diopter. He found that after using these a short time his asthenopia increased, so went back to his old glasses. He could not wear them with comfort, however, and, when in the light, had to put on dark glasses. In this case one-eighth diopter removed all the symptoms, and he was able to wear his glasses without any inconvenience. I have found that patients, as a rule, are very prompt to distinguish between one-eighth and one-quarter of a diopter if the amount of astigmatism is only very slight, and they discover even more promptly the difference between onequarter and one-half of a diopter of a cylinder if there is only the slighter degree of astigmatism present. If the degree of the astigmatism is, however, greater than the difference between the correcting glass and the next number weaker, it is not always so readily distinguished. DR. F. P. CAPRON of Providence. - I have been explaining to my patients that they can overcome the slight degrees by an effort, but cannot the higher ones without suffering. That seemed to me a plausible explanation. It was the effort, I suppose, which gave them the headache. I have been accustomed to explain the pain attending slight degrees of astigmatism upon the ground that in such cases the eyes are so nearly normal that they can be made so by a muscular effort, but the very effort causes the pain, while, in higher degrees, no effort will bring about such a result, and the patients content themselves with their imperfect vision and make no attempt to improve it. DR. SAMUEL THEOBALD of Baltimore. - In one respect Dr. Mittendorf's statistics are unique. I believe he said that in fifty per cent. of his cases there was simple hypermetropic astigmatism. I think if he had taken the same care to look for slight degrees of hypermetropia that he did to discover low grades of astigmatism his cases of compound hypermetropic astigmatism would have been greatly increased and his cases of simple hypermetropic astigmatism cut down. His statistics certainly are at variance in this respect with my own.

NORRIS: Cones and Rods of the Human Retina. 347 DR. RISLEY. -These cases were corrected without mydriatic. Perhaps that accounts for it. DR. THEOBALD.- I think not. DR. MITTENDORF. - Only the manifest hypermetropia was taken into account. Weak convex lenses absolutely were refused and cylinders accepted and gave perfect vision. THE TERMINAL LOOPS OF THE CONES AND RODS OF -THE HIUMAN RETINA, WITH PHOTOMICRO- GRAPHS. By W. F. NORRIS, M.D. PHILADELPHIA. In March, I894, in collaboration with Dr. James Wallac&, I published in the University Medical Magazine a paper on this subject. Having since that time, by repeated examinations of retinal tissue, become still more convinced of the correctness of the statements therein made, and having other photomicrographs for demonstration, I desire to call the attention of the society for a few minutes to what seems to me an important advance in our knowledge of the minute anatomy of that complex end organ, the retina. It is well known that the external segments (members) of the cones and rods are usually described as ending in free extremities or tips which are in close proximity to the pigment layer of the retina, and often covered by and enveloped in it. Some investigators have spoken of them as ending in a swelling or knob. The photomicrographs, which I herewith exhibit, show that the external extremities of the cones and rods are loops, the outer member of a cone bending over to become continuous with the outer member of an adjacent rod, or less frequently with the outer member of another cone (twin cones). Adjacent rods unite also by their curved outer segments, ending thus also in peripheral loops. Taking a portion of the retina in the macular region we find the outer segment of each cone becoming cylindrical, apparently