DISEASES OF THE CRYSTALLINE LENS 417 



in diabetes, and the lens undergoes a retrogressive metamorphosis due 

 to disturbance of its nutrition. 



There is no doubt that cataract is also caused by inflammatory- 

 processes of the eye, and the nutritive supply of the lens becomes dis- 

 turbed and its normal condition impaired, such as ulcerations of the 

 cornea with central perforation, inflammation of the meml^rane of the 

 lens and iris, and also bleeding into the anterior chamber. Injuries 

 of the lens and concussions of the eye also cause a number of cases of 

 cataract. 



Certain conditions are developed as the result of concussion of the 

 eye and appear quite frequently; they may be thus briefly described: 

 The lens either sinks downward with the capsule or becomes laterally 

 displaced. It may lean against the iris or it may drop forward into 

 the anterior chamber of the eye, and it may finally crowd into the 



Fig. 142. — Gray cataract of both eyes. 



vitreous humor. If the lens has undergone but slight displacement 

 (subluxation), it may remain clear for some time, but the vision is 

 much impaired. If it has fallen into the anterior chamber or has been 

 forced into the vitreous humor, we see a rapid development of the 

 cataract, and in the later stages considerable inflammation of the choroid 

 membrane of the iris, or of the whole eyeball. 



Clinical Symptoms. — In cases where the disease is somewhat ad- 

 vanced, and the cataract is fully developed into one of the following 

 forms — punctiform, streaked, spotted, or complete opacity of a whitish- 

 blue, brownish-blue, or mother-of-pearl color — it is easily recognized 

 (Fig. 142) ; but, on the other hand, where there is a mere cloudy dimness 

 and small spots of cataract, we must use candle-light or some illumi- 

 nating power such as an ophthalmoscope and a strong light to see the 

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