SPECIFIC OR PERIODICAL OPHTHALMIA. 499 



SPECIFIC OR PERIODICAL OPHTHALMIA. 



This ruinous affection of the eyes is distinguished from 

 the simple disease by the constitutional disturbance which 

 accompanies it ; it is also characteiised by affecting the more 

 deeply-seated humours. The attack is made on the inner 

 structures of the eye, the external covering being only 

 sympathetically involved. 



The appearances which accompany the affection are not 

 always the same : those more commonly present are swelled 

 eyelids, which appear nearly closed, and when separated 

 exhibit a sunken retracted eyeball, giving the eye the ap- 

 pearance of being diminished. This arises from the re- 

 tractor muscles acting to withdraw the eye from the stimulus 

 of light, and the horse resists every effort to force open the 

 lids, if the attempt be made in front of a strong light ; but 

 turn the head away, and the animal will unclose the eye. 

 This retraction of the eye at the same time forces the haw 

 over a portion of its globe, where it is seen swelled and 

 preternaturally red, from its participation in the disease. 

 The inner lining membrane of the lids will be found highly 

 vascular and hot, pouring forth, in most instances, a flood 

 of tears, which continually trickle down the face ; and the 

 whole conjunctiva will present a network of turgid red 

 vessels over its opaque white surface. If the cornea be not 

 too opaque or too much inflamed, we shall discover the 

 aqueous humour thick and muddy also ; the iris and choroid 

 will likewise be found altered from their natural colour. 

 From this state it follows sometimes, that a central yellow 

 patch is discovered at the bottom of the eye ; in which case 

 matter has formed, from the usual suppurative inflamma- 

 tion, but it most commonly becomes absorbed again, and 

 sometimes very speedily. In very acute cases, however, 

 there is a large deposit of fluid, which disorganizes the eye. 

 The rapidity of the changes in the state of the eye is a very 

 marked feature of specific ophthalmia ; and the transition 

 from a most opaque to almost a clear state of the cornea, 

 and from a simple dimness in the appearance to a perfect 

 opacity, sometimes occurs in a remarkable short space of 

 time. We have seen an eye opaque within and without, 

 which was merely dim the night before ; and perhaps, within 



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