CAUSES OF FAILING EYESIGHT.

Mataura Ensign, Volume 7, Issue 365, 13 June 1884, Page 3

CAUSES OF FAILING EYESIGHT.

The causes to which deterioration of eyesight has been attributed are 'alleged ■to be cross-lights from opposite windows, li<rh't shining directly on the face, insufficient'light, .small print, and to, the position of the desk, forcing the scholar .to. bend! over, and ib'ring ; the eyes too close to thp book. or,-, writing paper, etc. But (says 'Popular Science' for January),

were all theses defects remedied, the integrity of the eye would not be restored nor its deterioration prevented. The chief causes of the evil would still remain. These are colors of the paper and ink. White paper and black ink are ruining the eyesight of all reading nations. The " rays of the sun," says Lord Bacon, " are reflected by a white body, and are absorbed by a black one." No one dissents from this opinion ; but, despite these indications of nature and of philosophy, we print our books and write our letters in direct opposition to the'suggestions of optical science. When we read a book printed in the existing made, we do not see the letters which, being black, are non-reflective. The shapes reach the retina, but they are not received by a spontaneous, direct action of that organ. The white surface of the paper is reflected, but the letters are detected only by a discriminative effort of the oitio nerves. This efEort annoys the nerves, and when Ions? continued, exhausts their suspectibilitv. The human eye cannot long sustain the broad glare of a white surface without injury. The author of '" Spanish Vistas," in ' Harper's Magazine ' says of Cartagena, that " blind people seem to be numerous there, a fact which nny be owing to the excessive dazzle of the sunlight and the absence of verdure." M r So ward, in his tour around the world, observed that "in Egypt ophthalmia is universal," attributing it to the same "excessive dazzle " of the wide areas of white sand ; and tlic British soldiers in the late campaign in that country, exhibited S3 r mptonis of the same disease. In the Smithsonian report for 1877, it is stated, in a paper on " Color Blindness," that M. Chevreul has produced 14,420 distinguishable tints of the elementary colors, from which the paper manufacturers could select colors more agreeable to the eye than the dazzling white, so weakening and lacerating to the nerves of that delicate organ.