THE SPECIAL SENSES. 139 



be too shallow or too deep, that is, the retina may be too 

 near or too far away from the lens. 



16. Hygiene of the Eye. After middle life, and as age 

 advances, most persons find their eyesight defective. This is 

 commonly due to a loss of power in the little muscle, and the 

 lens can no longer adapt itself to varying distances. This 

 condition should' not be neglected. The extra effort to see 

 distinctly will make matters worse. Suitable glasses should 

 be used without delay. As the years advance, stronger ones 

 will be necessary. This long-sightedness is not uncommon in 

 childhood, and may be seen sometimes in several members 

 of the same family, on account of their having the same 

 formation of eye. It w~ould be well for teachers, as well as 

 parents, to be on the look-out for such cases, and have the 

 defect remedied by having the child wear suitable glasses, at 

 least during study hours. If not attended to, the evil will 

 likely increase and may lead to squinting. Short-sightedness 

 is also not uncommon, and is said to be on the increase. 

 Prolonged .application to study may bring about this con- 

 dition of sight, or constantly holding the book too near the 

 eyes. The use of glasses is here also a necessity. Short- 

 sighted children at school are apt to lean forward over the 

 desk. Note the habit and search for the cause. Fine print 

 should never be used in schools, nor the eye taxed for any 

 length of time in any way. 



Reading as we lie on a couch or on a bed, the prevailing 

 custom of reading on the railway train, reading fine type in 

 twilight, or in a dim light, are all habits which should be 

 strongly condemned. 



Constitutional diseases, especially scarlet fever, are often 

 followed by weakness of sight. After a severe illness the 

 eyes should be used with great caution. If reading, or other 

 use of the eyes, causes them to ache, or brings on a pain in 

 the forehead, it should be discontinued at once. 



