SPECIFIC OPHTHALMIA. 193 



wasliing ihe eye witli a very weak solution of nitrate of silver or sulphate 

 of zinc. 



Opacity of the lens is another consequence of specific inflammation. A 

 white speck appears on the centre of the lens, which gradually spreads 

 over it, and completely covers it. It is generally so white and pearly as 

 not to be mistaken ; at other times it is more hazy, deceiving the inex- 

 perienced, and occasioning doubt in the mind of the professional man. We 

 have seen many instances in which the sight has been considerably aSected, 

 or almost lost, and yet the horse has been pronoimced sound by very fau' 

 judges. The eye must be exposed to the light, and yet under the kind of 

 shelter which has been already described, in order to discover the defect. 

 The pupil of the horse is seldom black, like that of the human being, and 

 its greyish hue conceals the recent or thin film that may be spreading 

 over the lens. 



Confirmed cataract in the eye of the horse admits of no remedy, for two 

 obvious reasons : the retractor muscle di'aws the eye back so powerfully 

 and so deeply into the socket, that it would be difficult to perform any 

 operation ; and should an operation be performed, and the opaque lens 

 removed, the sight would be so impei-fect, from the rays of hght not being 

 suffi-ciently converged, that the horse would be worse to us than a blind 

 one. The man who has undergone the operation of couching may put a 

 new lens before his eye, in the form of a convex spectacle ; but we cannot 

 adapt spectacles to the eye of the horse, or fix them there. 



Since the pubHcation of the first edition of ' The Horse,' some commu- 

 nications have been made in the seventh volume of the ' Veterinarian' 

 A\'ith regard to the occasional apjiearance and disappearance of cataract 

 without any connection with the common moon-blindness. It is there 

 stated, that cataracts might be formed in a fortnight or thi'ee weeks ; that 

 many instances had been known in which they had been completed in less 

 time, and A^dthout any previous apparent disease of the eyes ; and that 

 they had been detected on examination, when the owners had not the 

 slightest suspicion of disease in the eye. These cataracts, however, were 

 very minute, and occasionally were found after a time to have disappeared. 

 They difiier entirely from the cataracts produced by the repeated attacks 

 of specific ophthalmia, in being small and temporary, and in the other tissues 

 of the eye remaining intact. 



That excellent veterinarian, Mr. Percivall, had a case of this description. 

 A gentleman brought a horse one morning to the hospital, in consequence 

 of its having fallen in his way to to"\ATi, and grazed his eyebrow. On 

 examining him carefully, the cornea was partially nebulous, and a cataract 

 was plainly visible. Neither of these defects was sufficient to attract the 

 notice of any unprofessional observer, and both were unconnected with the 

 slight bruise prodiiced by the fall. The ovmer was told that the corneal 

 opacity might possibly be removed ; but as for the cataract he might 

 regard this as beyond the reach of medicine. He retui-ned with his horse 

 on the fifth day, saying that the physic had operated well, and that he 

 thought the eye was as clear as ever. ]\Ii\ Percivall examined the eye, 

 and could discover no rehc either of the corneal opacity or of the cataract. 



The opinion respecting cataract is therefore essentially modified. It 

 may not of necessity be the result of preA"ious inflammation, although in 

 the great majority of cases it is so, nor does it always lead to blindness. 

 Still it is a serious tiling at all times, and, although existing in the 

 minutest degree, it is unsoundness, and very materially lessens the value 

 of the horse. 



'Were I asked,' says Mr. Percivall, 'how the practitioner could best 

 distinguish a cataract of the above description from that which is of ordi- 







