114 DISEASES OF THE EYE. 



CaxsaRACT. 



The definition of the term cataract Is an opacity of the crystalline lens, 

 or of its capsule, or of both. 



To render this more intelligible it is necessary to briefly consider the 

 anatomy of this portion of the eye. The ciystalline lens is a transparent, 

 double convex body, situated immediately behind the pupil. The func- 

 tion of this lens is to produce distinct perception of form and outline, and 

 to accommodate the eye to vision at different distances. 



The capsule of the lens Is a transparent and highly elastic membrane 

 ■which closely surrounds it. 



Causation^ — Cataract, especially capsular, maybe caused by wounds 

 and injuries to the lens, its capsule, or to the eye itself. It is attributed to 

 inflammation, and has been produced artificially in animals by modifying 

 the oonstitation of the blood. From this it is to be inferred that certain 

 derangements of circulation and the genei'al system may Induce cataract. 



Two forms of cataract are recognized, the soft and the bard; the latter 

 is peculiar to advanced age. 



Symptoms . —In cataract of the capsule, there will be seen behind the 

 pupil a non-transparent body of a gray, dead white ; if cataract of the lens 

 exists, the body will be bluish-white or amber colored. 



After a certain age an unafl'ected lens acquires a yellow color, then 

 changes to an amber. 



In hard cataract the cloudiness appears in this already discolored lens, 

 and great impairment of vision may result before the grayness is plainly 

 evident on a superficial examination. 



Treatment. — When the characteristic changes m the eye are detected, 

 every means to improve the general health should be resorted to. Tonics 

 if Indicated are to be given, and selected as the need is manifest. 



The employment of the most judicious methods can have no other influ- 

 ence on the disease than to possibly retard its progress. Nothing can 

 exert a curative Influence exoeiDting the knife of a siu-geon. 



