The simplest and at the same time the most concise definition of myopia is given by my friend and former teacher, Dr. Landolt, of Paris, when he says that "myopia is present whenever the retina is situated behind the focus of the dioptric system of the eye." Before proceeding with the remarks, on the means of preventing or limiting the development of myopia or near sight it will be well to give a brief outline of some of the principal causes of the affection, and for this purpose I have looked up the leading authorities on the subject. Schweigger, of the University of Berlin, is of the opinion that in the majority of cases myopia is congenital, or inherited, or, at least, there is a predisposition to it contracted through the parents. It occurs in early childhood and shows with the increase of years a progression both in frequency and