In this disease, the condition of the eyeball is the opposite of that in long-sight; that is, the eyeball is too long. Fig. 452. The tendency to short-sight in some cases exists at birth. In a great majority of cases, however, it is the result of improper use of the eyes. It is particularly frequent among students and literary people, which is probably due to the sedentary habits of this class of persons, and especially the habit of using the eyes much in close work.

The disease is very prevalent in Germany, so much so that the government has found it necessary to allow the use of glasses among soldiers.

Fig. 452. Eye Ball of Short-sighted Eye.

Fig. 452. Eye Ball of Short-sighted Eye.

It is very rare indeed among farmers, sailors, and common laborers. Among savages it is still more rare, if not unknown. An eminent oculist of Breslau, some years ago examined the eyes of over ten thousand school children, with the result of discovering that short-sight increases in students with the length of time the person is in school. In the elementary school, 6.7 per cent of the students were found to be short-sighted. In the next higher grade, the percentage was 10.3. In the high school, about one in every five suffered with myopia, and in the universities or colleges, more than one in every four was so affected. In the high school, nearly one-half of the first class were found to be short-sighted. Examinations made in this country have developed similar facts. The idea sometimes entertained that the short-sighted eye is a strong eye, is a mistake. As a general rule, short-sight is an evidence of unsoundness and disease, which may result in most serious consequences to the sight, possibly ending in its destruction. Short-sight does not, as many people suppose, diminish with age. Although a person may become able to see near objects better than in youth, distant objects do not become more distinct.

Short-sight may be relieved by the use of concave lenses. Fig. 453 placed before the eye, by means of which the error in vision arising in consequence of too great length of the eyeball may be corrected. Persons with short-sight generally do not need glasses in reading, unless they are obliged to hold print very near to the eye, but are wholly dependent upon properly fitted glasses for vision at a distance. Wearing of properly fitted glasses is an advantage rather than a detriment to short-sighted eyes, but care should be taken to secure an accurate adjustment of the glasses to the eye. This can only be done by a competent physician who has given his attention to the subject. In addition to the fitting of proper glasses, attention should be given to the general health, and to careful removal of all causes of this condition.

Fig. 453. Bi-Concave Lens.

Fig. 453. Bi-Concave Lens.