256 Prevention of Myopia
disposition to attribute myopia to hereditary tenden cies;1 but no satisfactory evidence on this point has been brought forward, and the fact that primitive peo ples who have always had good eyesight become myopic just as quickly as any others when subjected to the con ditions of civilized life, like the Indian pupils at Car lisle,2 seems to be conclusive evidence against it.
In spite of the repeated failure of preventive measures based upon the limitation of near work and the regula tion of lighting, desks, types, etc., the use of the eyes at the near-point under unfavorable conditions is still ad mitted by most exponents of the heredity theory as probably, if not certainly, a secondary cause of myopia. Sidler-Huguenin, however, whose startling conclusions as to the hopelessness of controlling shortsight were quoted earlier, has observed so little benefit from such precautions that he believes a myope may become an engineer just as well as a farmer, or a forester; and as a result of his experiences with anisometropes, persons with an inequality of refraction between the two organs of vision, he even suggests that the use of myopic eyes may possibly be more favorable to their well-being than their non-use. In 150 cases in which, owing to this in equality and other conditions, the subjects practically used but one eye, the weaker organ, he reports, became gradually more and more myopic, sometimes excessively so, in open defiance of all the accepted theories relating to the matter.
The prevalence of myopia, the unsatisfactoriness of
1 It seems to have been amply demonstrated, by the studies of Motais, Steiger, Miss Barrington, and Karl Pearson, that errors of refraction are inherited. And while the use of the eyes for near work is probably a sec ondary cause, determining largely the development of the defect, it is not the primary cause.-Cyclopedia of Education, edited by Monroe, 1911-1913, vol. iv, p. 361.
2 Fox (quoted by Risley) : System of Diseases of the Eye, vol. ii, p. 357.