Short-sighted persons are generally born so, and the affection is noticed in early childhood; but it may be brought on in youth by too close attention to study, and by habits of looking at minute objects, which irritate the eye. It is a popular error to imagine that the sight improves as the individual grows older.


The eyes should be exercised and accustomed to look at distant objects. When children display any tendency to short sight, their studies should be abridged, and they should have plenty of exercise in the open air. If the patient can got on comfortably without glasses, it is better not to use them, but if the eyes feel fatigued after any ordinary use of them, then the patient may use glasses, and, if necessary, wear them continually. The patient should choose a pair that enables him to see objects within forty feet, as distinctly as other people; but should not have them so concave as to make objects appear dazzling, or smaller than usual.

Long-sightedness is one of the earliest symptoms of impaired nutrition in old age. The patient must resort to glasses; but he should defer the use of them as long as possible, as, having once commenced the use of them, it is difficult to leave them off; nor should he change those first selected for stronger ones till he is absolutely compelled; and the sight should be spared by candlelight as much as possible. The glasses should cause minute objects near the eye to appear bright and distinct, but not larger than natural. If they do, they are too convex.