PERIODIC OPHTHALMIA. 113 



before of a brownish hue, changes to a sort of greyish colour, 

 and part of it becomes absorbed. This greyish deposit is 

 usually in connection with the crystalline lens, and may be 

 regarded as the forerunner or basis of a cataract. Another 

 peculiarity of this affection is that in many cases, as soon as 

 the attack ceases in one eye, the other eye becomes affected, 

 and often the disease reappears in a month or so without 

 any visible cause for the second attack. Again, a case may 

 appear to be getting along finely, the eye improving rapidly, 

 etc., when it will suddenly change, the intensity of the in- 

 flammation become augmented, and the eye in every respect 

 worse than ever. In examining as to soundness, a wrinkled 

 eyelid covering an eye that appears smaller than its fellow 

 is to be regarded with suspicion, as in such a case the pro- 

 babilities are that the eye has suffered from two or three 

 attacks of periodic ophthalmia. In the early stage of the 

 disease there is usually a slight increase of the animal tem- 

 perature, the pulse may be slightly quickened, and the 

 animal observed to be duller than usual. Slight loss of 

 appetite may also be observed in some cases. As a rule, each 

 succeeding attack is marked by increased severity, until loss of 

 vision results, when, generally, the inflammatory action ceases, 

 never to return. There are, however, some well authen- 

 ticated cases in which the eye, having become completely 

 disorganized by the disease, still continued to suffer from 

 inflammatory attacks at periods varying more or less in regu- 

 larity, and in the same way that it had suffered before loss of 

 vision had taken place. Such cases, however, are very rare. 

 Treatment. — The treatment of periodic ophthalmia is any- 

 thing but satisfactory, and, so far as our present state of 

 knowledge goes, we know of no remedy that will cure the 

 disease. Hence the treatment can only be palliative, and is 

 adopted with the view only of mitigating the severity of the 

 attack. Both constitutional and local remedies are to bd 



