274 HUMAN PHYSIOLOGY CHAP. 



dangerous nervous diseases. These defects should be 

 corrected by using spectacles or eye-glasses, properly 

 adjusted, or by an operation, as the case may require. 



With a set of Snellen's test-types, make an examination of your 

 own eyes. Test for nearsightedness, farsightedness, and astigmatism. 



189. Care of the Eyes. Although the eye is a delicate 

 and sensitive organ, it has a wonderful power of accom- 

 modation, and, under favorable conditions, can do an 

 immense amount of work. That is why the eyes are 

 so often abused. It is only after they have become 

 diseased and cause discomfort that they are given any 

 special care by most persons. Let us 'learn a few of 

 the more important things about the use and care of 

 healthy eyes. 



1. After diseases, like measles, diphtheria, and scar- 

 let fever, the eyes are weak and should not be used for 

 close work for several weeks. At such times it is an 

 easy matter to permanently injure the eyes. 



2. Do not overwork the eyes by reading, writing, 

 sewing, or doing any kind of close work, when they 

 smart or tingle. When the eyes are tired they should 

 have rest. 



3. Do not work facing a strong light. It should come 

 from the rear and over the left shoulder to be most 

 comfortable. 



4. All close work should be done during the daytime 

 and in the best of light. The twilight of the early 

 evening has ruined many good eyes. 



5. The position of the body is very important in the 

 proper use of the eyes. You should not read lying 



