WORM IN THE EYE. 121 



consisting of an incision or puncture through the cornea, 

 allowing the aqueous humour and the worm with it to pass 

 out. In the majority of cases the patient will need no 

 preparation for the operation. In every case the animal is- 

 to be cast, and firmly secured. Elevate the head to a cer- 

 tain extent, placing it in a position convenient for operating 

 on the eye. Transfix the membrana nictitans with a tena- 

 culum or some other suitable instrument. For making the 

 incision, use a sharp lancet, such as is used in human 

 practice. Have it guarded, so as to expose only so much 

 of the point as is necessary, by wrapping it with thread. 

 Make an incision through the cornea, passing the lancet as 

 quickly as possible. As soon as the incision is made, the 

 aqueous humour will escape pretty forcibly, and, as a rule, 

 the parasite comes out with it. In case the worm does not 

 escape with the aqueous humour, place the animal in a 

 darkened box, and keep him quiet for a few days, until the 

 aqueous humour re-accumulates ; after which operate 

 again. In case the worm can be removed in no other way, it 

 becomes advisable to pass a pair of microscopic forceps 

 into the chamber, seize the parasite, and remove it. The 

 incision should be made at the superior part of the cornea, 

 at its junction with the sclerotica, and in a slanting direc- 

 tion, to have it heal rapidly. 



Myopia (or Near-sightedness). — This condition is caused 

 by an abnormal condition of the eyeball, which becomes 

 elongated from before backwards, and too great convexity 

 of the crystalline lens, and probably also of the cornea. It 

 causes shying, etc. In some cases it may wear away as the 

 animal grows older. In man this defect is remedied by 

 using concave glasses ; but as it i& not possible to remedy 

 the defect in the lower animals by applying glasses, and as 

 no other remedial measure is known, it is usual to let the 

 animal go Avithout treatment. 



Hypermetropia. — This is the opposite condition to the 



