366 DISEASES OF THE EYES. 



after ten or twelve years — is what is known as senile cataract; 

 this is slow in its development, while cases of opacity of the lens, 

 which are observed in young animals, appear frequently without 

 any marked cause. Haltenhoff was able to recognize traces of 

 sugar in the urine of a dog which became very thin and anaemic 

 in a short time, and developed cataract. The author has tested the 

 urine of many dogs affected by blindness caused by cataract, but 

 has never been able to find any sugar. 



Inflammatory Process of the Bye. There is no doubt that 

 cataract is also caused by inflammatory processes of the eye, and 

 the nutritive supply of the lens becomes disturbed and its normal 

 condition impaired, such as ulcerations of the cornea with central 

 perforation, inflammation of the membrane of the veins 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 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 

 advanced, and the cataract is fully developed into one of the fol- 

 lowing forms : punctiform, streaked, spotted, or complete opacity 

 of a whitish-blue, brownish-blue, or mother-of-pearl color, it is 

 easily recognized ; but, on the other hand, where there is a mere 

 cloudy dimness and small spots of cataract, we must use candle- 

 light or some illuminating power such as an ophthalmoscope and 

 a strong light to see the action of the lens in the eye itself. 

 Before doing so, however, we must dilate the pupil with atropia. 



The prognosis is rather difficult U make, and, as a rule, it 



