At first a sense of slight inconvenience is felt; but, if the attempt be continued for a considerable time, vertigo, nausea, and vomiting may result. This result does not occur if one of the eyes is closed. Hence, the disturbance is in the confusion arising from efforts at perfect binocular vision. But precisely this confusion of effort exists in the hypermetropic person, and if the continuance of such a course of perplexity for a few minutes or hours will result in so serious nervous disturbance as is shown in the illustration, is it not reasonable to suppose that a similar confusion of effort continued through many years may constitute a permanent source of nervous irritation? Similar perplexity results when either the internal or external recti or other long muscles are insufficient to the performance of their functions by the normal nervous impulse. A difficult and more complicated perplexity arises in case of astigmatism, and still other nervous confusion is the result of myopia. Hence all these abnormal states, whether from defects in the form of the eyes, or in the motor apparatus involved in associated movements, may give rise to nervous perplexity and irritation. But it has been shown that the effects of such perplexity or irritation in one part may be experienced in a distant part, and this principle is illustrated in the case of the young person who may induce vomiting by using magnifying spectacles.

However reasonable such a theory may appear, it can not be accepted as of practical value until it is shown that practical results may be deduced from its

application. I shall attempt to show that such results may follow with a surprising uniformity-first, by citing a single instance illustrating the effect of correcting each of the more commonly recognized defects of refraction and association; second, by considering at greater length several of the more familiar conditions of nervous disturbance; and third, by attempting to show the results of such corrections in a given number of consecutive nervous disorders of serious nature.

The first observation is the case of a lad aged seven years, whose mother brought him for treatment of the eyes in 1873. The immediate reason for the consultation was pain experienced in and above the eyes. He was nervous, suffering severely from chorea, from which he had not been free for two years. He was weak, had no inclination for the amusements of childhood, and was often ill in various ways. He was found to have hypermetropia in high degree. Appropriate glasses were directed, which greatly pleased him. Recovery from his nervous troubles commenced at once. The change was rapid and remarkable. The lad continued to gain strength, and was, within a few weeks, in all respects in better health than ever he had been before. Although ten years have passed, there has been no return of nervous troubles.

A lady, aged twenty-one, had suffered so greatly from facial neuralgia during many years that, among other radical measures for relief, she had submitted, by medical advice, to the extraction of all her teeth, notwithstanding they were sound. She was found to

have astigmatism, and strong cylindrical glasses were prescribed. The neuralgic paroxysms ceased within a few days, and have not returned during eight years.

A gentleman, aged twenty-eight, an extremely neurotic subject, was seen in January, 1877. He had for several years suffered from dorso-lumbar neuralgia. He was extremely sensitive to the influence of cold. A slight draught of air impinging upon the back was sufficient to bring on a paroxysm so severe as to confine him several days in his bed. He slept poorly, and so excessive was his general nervous derangement that he sometimes felt himself upon the boundary of insanity. He belonged to a neurotic family. His mother died insane. One of his brothers was insane, and a sister had been an invalid for several years from some nervous disorder. He was myopic, with a slight astigmatism. Glasses to meet these conditions were prescribed and used. Nine months later he called to say that he was entirely cured, and that the relief had been immediate.

A lady who had suffered from facial neuralgia of intense character during many years, was found to have insufficiency of the internal recti muscles. Tenotomy of one of the external recti was performed, since which time, although six years have elapsed, she has had no attack of her complaint.

These instances serve as illustrations of irritation arising from uncomplicated errors of refraction, or of association, and of the relief often obtained by the correction of these uncomplicated errors.

But it often happens that these anomalies are not

uncomplicated. Thus, refractive errors, such as hypermetropia or myopia, are often associated with muscular insufficiencies, either of those directing the eyes laterally, or of those which move them in the vertical direction. Again, insufficiency of either of these muscles may be associated with weakness of the muscle of accommodation. These are but a few of the complications which may be found, and, in many of these nervous complaints in which the predisposing irritation is found in the eyes and their motor apparatus, the simple correction of a refractive error is by no means sufficient to bring relief to the nervous condition. When once a neuralgic, choreic, or epileptic habit has been long established, not only may it be necessary to remove the principal source of irritation, but all irritation, before the habit will be discontinued. It must not, therefore, be supposed, even if the hypothesis that refractive and muscular errors of the eyes constitute a very important factor in the neuropathic condition, that the simple adjustment of a pair of glasses, or the simple relaxation of a muscle, must of necessity establish the cure of a nervous disease.

The irritation experienced in and about the eyes, and in the forehead and temples, as a result of ametropia or muscular anomalies, is called asthenopia. It is a complaint for which oculists are very frequently consulted, and doubtless yields more readily than complaints arising from the same cause more distantly located, or of more severe nature; yet it is well known to oculists that even asthenopia does not al

ways yield to such simple measures as have been mentioned.

Hence the highest skill and most patient effort may be demanded for the removal of ocular disturbances which may cause nervous troubles, and the failure of efforts directed only to some prominent ocular defect would not of necessity argue against the probability that the eyes may, after all, be the seat of trouble. Bearing this in mind, we are prepared to examine more in detail a few forms of neuroses and their relations to ocular defects.

CEPHALALGIA OR HEADACHE.

The form of nervous disturbance more common than any other, perhaps, is headache. The habitual sufferers from this complaint are everywhere, and, inasmuch as the subjects of the disorder are usually able to be about, and generally to attend to the ordinary duties of life, they are forced to surrender themselves to the ever-returning torture with as much resignation as possible; and, after trying many remedies, almost all of which may, for a brief period, seem to modify their sufferings, they at length submit passively to their fate, with the comforting assurance that the disorder is constitutional, and that nothing can be done.

Although headaches take a variety of forms, an outline of the most characteristic features of the disorder may be drawn in such a general manner that the details of the picture may be easily filled in for an individual case.