instruments are provided with a concave mirror and a revolving disc containing a series of convex and concave lenses which can be rotated at will behind the perforation in the mirror.

Figure I represents the path of the rays when the ophthalmoscope is used in the direct method. In this method the observer sees the eye just as he would see an object through a convex glass or simple microscope. The

FIG. I. FORMATION OF THE IMAGE IN THE

DIRECT METHOD OF OPHTHALMOSCOPY.

image of the eye-ground is a virtual one; that is, it seems to be behind the eye. It is magnified and erect.

From the candle L, the divergent rays falling on the mirror O, are rendered convergent. Passing through the refractive media of the eye, they are rendered still more convergent and come to a focus in the vitreous humor; diverging again, they form on the retina, the illuminated circle, whose diamter is a b. If this eye is emmetropic, rays from the points x and y will pass out of the eye into the eye of the observer. All the rays from the point x will be parallel. Rays from the point y will also be parallel. No image is formed, but the rays continue their course, and, entering the eye of the observer, come to a focus on his retina at the points x and y.' Rays from the point x in the patient's eye unite at the point x' on the observer's retina. In a similar manner rays from the point y'in the patient's eye unite at the point y in the observer's eye. These rays, projected backward, seem to lie in their true position. Rays from the middle point m of the patient's eye unite on the middle point m of the observer's eye, and are projected backward to the point from which they originated. The point x, above m in the patient's eye, is represented by x in the observer's eye below the middle point m. The point y below The point y below m, in the patient's eye, is represented by y above m in the observer's eye. (The figure and explanation are from Dr. Schweinitz).

It is evident, from a study of the above diagram, that in order to see any details in the fundus of a patient's eye, the surgeon's eye must be in a condition to focus parallel rays of light upon its retina. In other words, it must

be emmetropic and he must be able to relax his accommodation as in distant vision; but we are all so thoroughly habituated to the use of the accommodation in looking at things close by that the first thing we have to learn in using the ophthalmoscope is to break this habit--to relax the accommodation at will, so that the eye of the surgeon, placed close in front of the patient's eye, is in a condition to receive parallel rays of light and to focus them upon the retina. In order to acquire this ability I have found it of service in approaching the patient or the eye-model in the dark room, to stare at the black wall as if looking into vacancy.

In my class work at Rush College, I have first given the students plain perforated mirrors and pill boxes with printing in the bottom and an aperture in the cover corresponding to the pupil of the eye, and they have practiced in the dark room, getting control of the light. They have also practiced the proper position in which the ophthalmoscope should be held-the handle held easily in the hand, the finger upon the side, and steadied by resting it against the nose and brow in such a way that whenever it is put up it comes naturally in position for the eye to see through the aperture. Then each student has taken his ophthalmoscope and gone through the same maneuvers with the pill box.

We also use a schematic eye, made by Queen & Co., constructed upon suggestions made by Dr. Wm. Thomson of Philadelphia several years ago. It is in accordance with strict mathematical formulæ, and consists essentially of two pasteboard tubes, one sliding

FIG. 2.

QUEEN'S MODEL OF THE EYE FOR OPHTHALMOSCOPIC PRACTICE.

into the other, the first one containing in the front part a convex lens of 20 diopters. At the back of the sliding tube there is a picture representing the retina, which can be brought nearer to or farther from the lens representing the refractive media of the eye. By this movement all refractive states of axial ametrophia up to 6 D. hypermetropia and 6 D. myopia can be exactly reproduced, and are read off by means of a scale on the sliding tube.

Each student has been asked to provide himself with one of these models to practice upon at home, as well as in the dark room in the college laboratory. There we have standards

upon the top of which are three of these schematic eyes; one is emmetropic, one is hyperopic and the other is myopic. Students have been advised to practice first, the examination of the hyperopic eye, because it is easy to see the details of the fundus without complete relaxation of the accommodation. When they are able to partially relax the accommodation and see the fundus of the hyperopic eye easily, they are advised to practice upon the emmetropic eye, first approaching from a distance, staring at the blank wall behind the model and gradually relaxing the accommodation. Suddenly they see the details of the painted fundus. When one is once able to do this, subsequent efforts are rendered very easy. Then we have them practice upon the myopic eye, and they very soon discover that it is quite impossible to see the details of the retina without employing the concave lenses which are contained in the ophthalmoscope. This is readily understood when we consider the path of the rays of light coming out from the myopic eye.

They come to the surgeon's eye convergent and must be made parallel or divergent by passing through a concave lens before they can be made to focus upon his retina. For this reason we have in the revolving disc of the ophthalmoscope a series of concave lenses which can be rotated at will behind the aperture of the mirror. Likewise, if the surgeon is myopic he must, in using the ophthalmoscope, either wear his correcting glasses, or what is more convenient, turn into the aperture of his instrument a lens equal in strength to the degree of his myopia. If the surgeon be hypermetropic he may first render his eye emmetropic by turning into the instrument a convex lens of proper strength.

If we desire to estimate the degree of myopia with the ophthalmoscope we may do so by finding the weakest convex lens, through which we may see the details of the eye ground clearly, after allowing for error in our own eye and completely relaxing the accommodation. Likewise we may estimate the amount of hypermetropia in an eye under the influence of a mydriatic by finding the strongest convex lens with which we can see the fundus clearly. Unless we have perfect control of our accommodation at all times, it is evident that the measurements cannot be depended upon, and the surgeon must also know the refraction of his own eyes and allow for any defect.

In using the ophthalmoscope by the indirect method we interpose between the instrument and the patient's eye a convex lens of about 3 inches focus and turn into the aperture of the ophthalmoscope a convex lens of 10 inches focus. A real, inverted image of the interior of the eye is formed and the method is similar in principle to that of the compound micro

scope.

The ophthalmoscope mirror O (Fig 3) is held at a considerably greater distance from the patient than in the direct method. The rays from the candle come to a focus before reaching the eye or object-lens. They then diverge, and, passing through the object-lens 1, are rendered convergent. After traversing the dioptric media of the eye, their convergence is increased, and once more they unite somewhere in the vitreous humor, from which point they diverge and form a circle of illumination on the retina. Their course, in passing from the candle until they reach the retina, is shown by the arrow-heads in the figure.

A portion of the retina, a to b, represented by the arrow, forms an image, b' a', between the lens and the observer's eye, represented by the inverted arrow. Rays from the point a, on the upper part of the retina, pass out of the eye parallel to each other. After passing through the object-lens 1, they are rendered

In

convergent and some to a focus at the point a' in the lower part of the inverted arrow. the same way rays from the point b on the lower part of the retina are parallel on passing out of the eye, but are rendered convergent by the lens 1,and come to a focus at a point b' in the upper part of the inverted arrow. It is this æreal image that the observer sees, and not the eye ground of the patient. Rays from this image are focused on the observer's eye, just as rays from the retina are focused in the direct method, i. e., the rays from the point a' are focused on a higher portion of the observer's retina, and rays from the point b' are focused on a lower portion. They are likewise projected back to the points in the image from which they originated. (De Schweinitz.)

By the direct method the objects seen are magnified about 15 diameters, but in the indirect method we obtain a view of a much larger portion of the retina at one time, magnified about 4 diameters. As in microscopy, it is best to examine specimens first with low power, so in ophthalmoscopy it is best to use first the indirect and then the direct method in every examination.

In the choice of instruments I give my

preference to those of the Knapp model, having the circular, fixed mirror, and containing about 15 lenses. Such an instrument can be had for about ten dollars and will not only last a lifetime, with good care, but is sufficiently elaborate for any examination which the general practitioner is called upon to make.

There are a number of atlases of ophthalmoscopy. That of Jaeger is most elaborate, but I know of no better guide for the student and general practitioner than "Medical Ophthalmoscopy" by Growers, already referred to.

DISCUSSION BY DR. H. T. PATRICK.

Mr. President and Gentlemen:

I thank you for your flattering invitation to say something of the use of the ophthalmoscope in nervous diseases. In return, I shall endeavor to avoid dry technicalities and to mention only such points as may be of use to every physician. No neurologist worthy of the name can practice without the routine use of the ophthalmoscope, and as every general practitioner must be a neurologist as well as gynææcologist, obstetrician, dermantologist and what not, he, too, if he would do good work, must be familiar with the instrument and know something of the things he sees with it.

In neurology the interest of ophthalmoscopy centers about the choked disc. As specific examples are generally more instructive and stick better in the memory than broad generalities, I beg your kind indulgence while I mention with the greatest possible brevity a few cases seen within the last year. They will serve at once as a practical introduction and as fair illustrations of the value, as well as the limitations, of the ophthalmoscope in neurology, for the instrument has its limitations as well as its uses. It is an efficient ally and may enable us to make a diagnosis when other means fail, but alone it is not enough and we are to count it only one of the many diagnostic aids, mental or mechanical, in our professional armanentarium.

Last spring I was asked to see a girl of 17 who had severe headaches, and had had several peculiar convulsions, the character of which led her physician to suspect hysteria. A careful review of the history and a careful examination pointed rather to tumor of the brain, and an examination of the eyes showed choked disc, which certainly excluded hysteria and made the diagnosis of tumor almost certain.*

The young man whom you have just had the opportunity of examining came to us for failure of vision only. Examination, as you have seen, revealed choked disc, which led to examination for other symptoms of tumor which were then found.

Shortly before I saw the young girl whom

Since the above discussion the case has come to autopsy, which confirmed the diagnosis.

I have just mentioned, I had referred to me a man, aged 34, who had been seen by two most excellent physicians. He complained simply of headache, occasional vomiting and some silght tingling now and then on the right side. One doctor gave him something for his stomach, the other something for headache. He had a sudden slight apoplectic attack with right hemiplegia and aphasia, at which time I first saw him and found double choked disc. Careful inquiry then elicited a history that comported well with the diagnosis of tumor and an approximate localization was not difficult. He was put on active specific treatment to exclude gumma before operation, when three days later he had a second apoplectic stroke, evidently from thrombosis due to the tumor, with complete hemiplegia, total aphasia and hemianopia, a condition for which an operation could do but little. Had an ophthalmoscopic examination been made earlier in this case it is possible that the tumor might have been located and removed, saving the man from subsequent total disability.

I saw a few weeks ago, with Dr. Colburn, a boy who had rapidly lost sight in the left eye and was rapidly losing it in the right. Examination of the nervous system was absolutely negative. Now, this sort of thing occurs, especially in young people, as one of the symptoms of hysteria, but Dr. Colburn could make out a blurring of the discs, and a few days later Dr. Mahoney found unmistakable choked discs which at once definitely excluded functional disease, or at least was positive evidence of organic trouble, a decision which the subsequent course of the case confirmed.

A few days ago I saw, with Dr. Manierre Jr., a young lady who had complained for several days of severe headaches, with vomiting. Headache and vomiting are symptoms that occur in a multitude of affections. Examination showed choked discs, which at once excluded a number of these affections. The choked discs did not serve to make the diagnosis, but they brought us near to it.

Last summer I saw, through the kindness of Dr. Henrotin, a young married man who was said by one of the very best and most careful diagnosticians in this city to have artero-sclerosis. True, he did have some artero sclerosis, but a glance at the optic discs would have shown at once that that was not his principal trouble. He had pronounced choked discs and the case ran the typical course of a rapidly growing brain tumor, probably carcinoma.

On two different occasions, in probably the largest nervous clinic in Germany, I was enabled to correct a false diagnosis by an ophthalmoscopic examination. Both were cases of brain tumor.

Now, for the reverse side of the shield. Some months ago Dr. John Bartlett sent a young

It may be well to note that we may have a combination of these two conditions.

In hydatid cyst of the brain, optic neuritis is frequent. In aneurism it is rare and occurs only when the aneurism is contiguous to the optic nerve or the optic tract. In hydrocephalus it is very rare. When I was an interne we had a case which was apparently a typica! one of hydrocephalus and the child had choked discs, but the autopsy showed that it was a case of extensive meningitis with large effusiona so-called external hydrocephalus which should not be classed as hydrocephalus at all. In epidemic cerebro-spinal meningitis choked disc is rare. In tubercular meningitis of the base, optic neuritis may appear and may even precede the other symptoms of the disease, but it is rarely very pronounced. There may also be tubercles in the choroid, but they are exceedingly rare in this disease, being more often found in general tuberculosis without meningitis. In syphilitic meningitis the choked disc is slower in development, but reaches a more intense degree. In pachymeningitis the examination of the fundus is generally negative.

What has been said regarding choked disc in tumors of the brain applies equally to abscess, except that it is not so frequent in the latter lesion and is more apt to be limited to, or decidedly more intense, upon the same side as the lesion. It is worhty of note that choked disc may appear in caries of the temporal bone when there is neither abscess nor meningitis.

There is a certain chronic cerebritis which may sometimes simulate brain tumor and in which we frequently have choked disc.

In cerebral hemorrhage, embolism and thrombosis there is choked disc only when the lesion is indirectly connected with the optic fibers, except that it sometimes occurs as a concomitant condition and is then due to co-, existing Bright's disease or artero-sclerosis. But we must remember that an apoplectic attack may be the first symptom of a tumor of the brain, due to a hemorrhage or acute softening within or around the tumor. In such a case of apoplexy we would probably find choked disc due, not to the apoplexy, but to the tumor.

You have probably seen it stated that in persons who have milliary aneurisms of the cerebral vessels, similar small aneurisms may be discovered on the retinal arteries, but this is not true, or at least if they are ever present, they belong to the rarest of clinical curiosities. What we do see occasionally are small extravasations of blood, but these are often present in patients who never have cerebral hemorrhage.

It is a curious fact that optic neuritis may appear in acute or sub-acute myelitis when

there is no discoverable anatomical connection between the cord and optic lesions.

Moderate choked disc occurs in a certain percentage (said to be as high as 8 to 10 per cent) of ordinary chorea. As we have seen, it may be a symptom of simple anæmia.

One word regarding optic atrophy. At least 50 per cent of all cases of simple optic atrophy show symptoms of spinal cord disease. Charcot was of the opinion that it is always due to locomotor ataxia. It is a singular fact that this optic atrophy occurs as an early symptom of locomotor ataxia and that when it does occur, the other symptoms of the disease remain stationary or never appear. Dejerine calls these "cases of tabes arrested by blindness." Of 400 cases of locomotor ataxia from Erb's private practice 6.75 per cent showed optic atrophy. Of 178 cases collected by Growers 14 per cent presented this lesion. The latter author mentions cases in which other symptoms of locomotor ataxia did not appear until 16 and 20 years, respectively, after the supervention of blindness, but it is not specifically stated that the knee-jerks were present, and our present knowledge would lead us to infer that they were absent.

Venetian Building, Chicago.

TUMORS OF THE LACHRYMAL GLAND.*

BY ADOLF ALT, M. D., St. Louis, Mo.

E.

Tumors originating in the lachrymal gland are of comparatively rare occurrence, so that the experience in this direction which may fall to the lot of any one man is not likely to be very great. In consequence the text-books, even those considered to be of the very best, give but little space to this subject. Treacher Collins, in his extensive report as curator of the Royal London Ophthalmic Hospital Museum, reports only one case of primary sarcoma of the lachrymal gland and adds, that adenomatous and carcinomatous tumors may also arise in this gland.

Schirmer, in Graefe and Saemisch (Vol. VII, I, page 7, etc.), gives a more detailed description of a resume of the literature on the subject up to his time of writing, and he agrees in the main with O. Becker, who maintained that the tumors of the lachrymal gland, which before him had been described under various names, as simple hypertrophy, adenoma, adenoid, colloid tumor, sarcoma, myoma, and encephaloid cancer, really constituted only one form of tumor which he termed adenoid.

However, since his publication a considera*Read at the ninth annual meeting of the National Association of Railway Surgeons, held at St. Louis, April 29, 30 and May 1, 1896.