I have never seen a child, or a teacher, who could look at a map at the distance without becoming nearsighted. German print, or Greek or Chinese characters, will have the same effect on a child, or other person, accustomed to Roman letters. Children learning to read, write, draw, or sew, always suffer from defective vision, because of the unfamiliarity of the lines or objects with which they are working. 1 Eyes and School-Books Pop. Causes of Defective Vision in Normal Eyes 79 Noise is also a frequent cause of defective vision in the normal eye.
All persons see imperfectly when they hear an unexpected loud noise.
Familiar sounds do not lower the vision, but unfamiliar ones always do. Country children from quiet schools may suffer from defective vision for a long time after moving to a noisy city. In school they cannot do well with their work, because their sight is impaired. It is, of course, a gross injustice for teachers and others to scold, punish, or humiliate such children. Under conditions of mental or physical discomfort, such as pain, cough, fever, discomfort from heat or cold, depression, anger, or anxiety, errors of refraction are always produced in the normal eye, or increased in the eye in which they already exist.