Recuri'ent Ophthalmia in Solipeds. Moonblindness. 415 



The crystalline lens is usually opaque, and may have undergone 

 various changes, fibrous, calcareous, or atrophic. The anterior 

 surface of its capsule has often adherent masses of black pigment 

 derived from the urea in previous adhesions. 



The vitreous humor and hyaloid membrane are sometimes clear, 

 but usually yellowish or blackish and reduced to one-half their 

 normal bulk b}^ accumulations under the retina. A dense exu- 

 date often exists on the lamina cribrosa. The choroid is very 

 uneven showing irregular rounded elevations, and like the iris is 

 the seat of active congestion, exudation and thickening. The 

 exudate on its surface raises and detaches the retina and, as shown 

 by Eversbusch, tliis may increase so that the retina from the two 

 sides may come together in the centre of the eye, the vitreous 

 having been absorbed and removed. Reynal records instances in 

 which the exudate had become cretified, or as he claimed trans- 

 formed into true bou}' tissue. Finally the optic nerve is atro- 

 phied, often in advanced cases to half its natural thickness. 



Prevention. As treatment is somewhat unsatisfactory there is 

 the greater reason to give attention to measures of prevention. 



In view of the great evil of low, damp, overflowed lands, it is 

 important to drain and improve such lands whenever possible, 

 and when tliis cannot be done, to abandon the breeding of horses 

 upon them, and to buy the animals necessary for agricultural 

 purposes from high, dry, healthy localities and introduce them 

 only after they have passed the age of five years at least. 



The improvement of wet lands b}' liming, so as to lessen the 

 amount of decomposing organic matter, and improve the charac- 

 ter of the vegetation has proved very beneficial in different parts 

 of England. The substitution for the products of marshy 

 meadows and wet lands, of those of dry cultivated meadow's and 

 lands is important. 



Misty cloudy regions in the vicinity of sheets of water, or cold 

 mountain ranges cannot be made wholesome, but they can be 

 abandoned for horse breeding, and devoted to more remunerative 

 uses. Something ma}' also be done by stabling the working horses 

 at night. 



An insufficient or debilitating diet, for example, in winter, 

 should be carefully avoided, the more so if it is to be followed by 

 a sudden access to rich grass in the spring. 



