274 THE CARE OF THE SENSE ORGANS 



insects find an easy entrance to them, in spite of the 

 quick closure of the eyelids. 1 The light may be so strong 

 as to irritate them or so weak as to make the effort to see, 

 a strain. The nature of the work they are called upon 

 to do may be too exacting and the hours of work too 

 long. 



Removal of objects. Dust, cinders and other foreign 

 bodies are usually washed out by the copious flow of 

 tears which their irritation causes, especially if the lid 

 is raised so as to free the object from the pressure be- 

 tween lid and eyeball. If the object is not thus removed, 

 it is a simple matter to pull down the lower lid, in case 

 it is lodged there, and wipe it off with the moistened 

 corner of a clean handkerchief. If it is under the upper 

 lid, the lid can be turned back by taking the eyelashes 

 between thumb and finger, raising the edge of the lid 

 outward, upward and finally backward, and at the same 

 time pressing down against the centre of the lid with 

 some slender object, as a match, in order to make the 

 inner surface of the lid turn outward. The object is 

 thus exposed to view and can be removed with the moist 

 corner of a handkerchief. If, in spite of these attempts, 

 the object still remains, a physician should be consulted. 



Effect of strong light. The eye is protected against 

 too strong a light by the reflex turning of the head 

 or shutting of the lid, which gives the iris time to con- 

 tract and thus make the pupil small. Any light which 

 remains disagreeably bright after this adjustment harms 

 the eye and should be carefully avoided. To look con- 

 tinuously at any bright object, as a lamp or an electric 



1 The muscles controlling the eyelids act more quickly than any 

 others in the body. It takes only about 0.05 of a second to close 

 the lid. If any object touches the tip of an eyelash, therefore, it 

 can get into the eye only if it is going faster than 10 feet per 

 second. 



