EXAMINATION OF HORSES 



can make out, independently of the structures I have 

 named. 



The oblique or focal illumination is the readiest and 

 best way of examining the anterior half of the eye. 

 By its aid we are enabled to examine, with great 

 minuteness, the appearances presented by the cornea, 

 iris, pupil, lens, and even the most anterior portion 

 of the vitreous humour. A candle or small lamp, and 

 an ordinary pocket lens of from two-and-a-half to 

 four-inch focus, is all we require. The light is held 

 in front and to one side of the eye, at a distance of 

 about a foot to eighteen inches, and on a level with 

 the eye; the flame is then brought to a focus with 

 the lens, and thrown first on the cornea, then on the 

 iris and crystalline lens; the examiner's eye, being 

 placed on the opposite side, in front of the horse's 

 eye, catches the rays emanating from the latter. By 

 shifting the cone of light from one portion of the 

 cornea or lens to another, we may rapidly, yet 

 thoroughly, examine its whole expanse, and detect 

 the slightest opacity. Opacities of the cornea or lens 

 appear by this reflected light of a light grey or whitish 

 colour. 



The catoptric test is a very useful one in diagnosing 

 cataract, and had better be used along with the obHque 

 illumination. It is conducted as follows : — A lighted 

 candle or taper is moved before the eye. If the organ 

 be healthy, three images of the light are seen. Two 

 of these images are erect, the third is inverted. The 



