360 ADVANCED PHYSIOLOGY 



and physical disturbances which follow in the wake of eye 

 defects should lead one to the most jealous care of these 

 priceless organs. Glasses should be fitted by a skillful 

 oculist as soon as it is discovered that the eyes are unable 

 easily to meet the demands upon them. The cost of this 

 sort of care should not be allowed to influence one in the matter 

 of procuring and following the most expert advice. 



If one has to hold a book nearer to the eye than 12 inches, 

 the indication, is that he is nearsighted. On the other hand, 

 if he finds it necessary to hold a book 20 inches or more from 

 the eyes to read it easily, the probability is that he is farsighted. 

 In either case he should consult an occulist. 



Some troubles due to imperfect eyes, such as headaches 

 and nervousness, are not always recognized as associated 

 with those organs. Sometimes a child in school is thought 

 stupid when the trouble is that he cannot see what is written 

 on the blackboard. A wise plan has been adopted in many 

 schools in recent years, under which the eyes of each scholar 

 are tested to determine whether or not he needs glasses. 

 Properly adjusted glasses not only bring relief to strained 

 eyes but so improve general health that everyone ought to 

 welcome an examination of his eyes, and if necessary the 

 adoption of proper glasses. 



In ordinary life, through ignorance and carelessness we 

 frequently use our eyes unwisely and in such a way as to 

 invite or increase a tendency to eye trouble. A few general 

 suggestions, therefore, may be profitably remembered by 

 everyone. 



Illumination. By changes in the size of the pupil consider- 

 able variation in intensity of illumination can be met, since 

 the pupil opens in dim light and closes in bright. Too dim 

 light, as for instance that at twilight, taxes the eyes severely 

 if one tries to use them for exacting work, like reading. On 

 the other hand, very bright light is equally injurious, so that 

 one should not allow sunlight to fall upon a page he is reading. 



