80 PERIODIC OPHTHALMIA, 



circle, being an extension of that which, in human medicine, is 

 called the arcus senilis*. 



At the beginning, the anterior chamber of the eye commonly 

 preserves its pellucidity, so that we distinctly view the iris and 

 pupil through it, the latter much contracted, the former unchanged 

 in colour ; but in the course of two or three or four days after- 

 wards — sometimes indeed on the very day of the attack — the 

 chamber becomes obscured by a dingy white or amber -coloured 

 deposit seen floating within it, through which the pupil is hardly 

 distinguishable, contracted as it is to the breadth of a broad line, 

 and looking more like the black eye of a garden-bean than the ovoid 

 aperture it was before. Supervening upon this, in some cases con- 

 comitant with it, we have obscuration of the cornea taking place, 

 arising from an extension of the conjunctival inflammation over it ; 

 and this, in very severe cases, is so intense that vessels carrying 

 red blood are perceptible upon its surface, shooting from all sides 

 of the circumference into a sort of circulus vasculosus, from which 

 others proceed, after the manner of radii, towards a common centre. 

 The obscuration of the cornea, though it may still leave the lymph 

 eff'used into the chamber of the eye visible, precludes us from dis- 

 tinguishing the pupil and iris ; and it is not until the inflammatory 

 action has abated that we regain a view of these parts. And this 

 constitutes the first or inflammatory stage of the ophthalmia, which, 

 generally, may be said to last from three to eight, nine, or ten days, 

 and longer, according to the intensity of the inflammation, as it 

 happens to be a primary or secondary attack, and to the condition 

 and situation of the horse at the time : in some measure, also, its 

 duration will be influenced by what happens to be done by way of 

 treatment. 



The Second Stage is marked by a gradual decline of the 

 inflammation, and, along with it, a tardy clearing of the cornea, 



* It is natural to the horse's eye to have a whitish border encircHng the 

 cornea ; but in health this is narrow and well defined ; whereas occasionally 

 under disease it will be found to have broadened considerably. "We owe to 

 Dr. Amnion the interesting observation that, in those eyes — in human 

 beings — where there is an arcus senilis of the cornea, a similar opaque ring 

 exists around the margin of the crystalline body." — Maclienue on the Diseases 

 of the {Human) Eye. Is this the case in horses under disease ? 



