844 DISEASES OF THE EYES. 



but it is probable that during life, the margin of the pupil 

 remains usually in contact with the lens, unless when the pupil 

 is dilated. At the same time, the contact is loose enough to 

 allow the worm to wriggle itself between the lens and iris. The 

 use of belladonna in the treatment of the inflammation of the eye, 

 is to prevent the iris, at the edge of the pupil, from permanently 

 adhering to the lens, which, if it remained in contact with the 

 lens, it would be apt to do, owing to the adhesive nature of the 

 inflammatory exudation. ^ The use of atropine (the active principle 

 of belladonna.) obviates the risk of adhesions being formed, by 

 causing the radiating muscular fibres of the iris to contract, and, 

 thus, to draw the margin of the pupil away from the lens. 



TREATMENT. — The moment what is the matter with the eye 

 has been found out, proceed to remove the parasite ; for the 

 longer it stays in the eye, the more harm will it inflict on that 

 organ. The usual manner of operating is as follows ; the only 

 instrument required being a Grsefe or Beer's cataract knife. Vet.- 

 Captain Appleton recommends a large suture needle, because it 

 rftadily punctures the cornea, and is not liable to hurt the iris, on 

 account of its curved shape. If none of these instruments be 

 available, use a fine-pointed lancet, the point being guarded by 

 thread wrapped round the blade, so as to leave about a quarter 

 of an inch bare. The horse should be cast on the side opposite 

 to that of the affected eye, and in such a manner that there will 

 be a good light on the part. A truss of straw should be placed 

 under his head, which should be steadied and kept down by the 

 assistance of a couple of men. The horse should be put under 

 chloroform, or the surface of the eye and haw (memhrana 

 nictitans) rendered insensitive by placing on it a few drops of a 

 10 per cent, solution, in water, of the hydrochlorate of cocaine 

 about ten minutes before making the incision. I would also 

 advise the use of a solution of atropine (p. 613). Before operating, 

 it is well to wash the eyelids and skin around the eye with warm 

 salt water (a teaspoonful of salt to a pint of water). The hands 

 ' and lancet should be thoroughly disinfected (p. 70). The operator 

 should kneel down behind the horse's poll and, holding the lancet 

 between the finger and thumb, while resting the hand close to 

 the eye and keeping the point of the instrument almost touching 

 the eye at the spot where it is intended to puncture, he should 

 wait until he finds the worm in a convenient position to make its 

 exit ; for, if it be hidden away behind the iris, the operation most 

 probably will be in vain. If the parasite is not between the iris 

 and cornea, he should wait until it comes in sight before com- 

 mencing. He should then make the incision by a strong, firm 



