348 DISEASES OF THE EYES. 



might be cleaned by gently syringing it with lukewarm water in 

 which boracic acid (say, 25 grains to the ounce) has been dissolved. 



The iDraotice of puncturing the cornea while the horse is standing, 

 is too dangerous to the eye to be adopted. 



Colonel Nunn performs the operation with a Beer's or Grsefe's 

 cataract knife, and makes the incision only just large enough to 

 introduce a human iris forceps, with which he seizes and removes 

 the worm. These instruments should be disinfected (p. 70) before 

 use. 



Worms under the Eyelids {Extra-ocular Filariasis). 



The presence of thread-worms between the internal surface of 

 the eyelids and the ball of the eye, sometimes causes considerable 

 irritation of the part; the chief symptoms being weeping, intoler- 

 ance of light, opacity of the cornea, and tenderness. In old-stand- 

 ing cases, the cornea may become rough and scaly. The worm in 

 question (filaria iial'pehralis) varies from J to ^ inch in length. 

 It is occasionally found in the canal (lachrymal canal) through 

 which the watery fluid of the eye escapes into the nostril. 



TREATMENT naturally consists in the removal of the worm, or 

 worms, which may be done by opening the eyelids, gently syring- 

 ing the part with warm saltish water (a teaspoonful to the pint), or 

 with a warm solution of boracic acid and water (5 grains to the 

 ounce of water), and picking out the worms when they come into 

 view. The manipulation in this case will be aided by placing in 

 the affected eye a few drops of a 5 per cent, solution of cocaine, 

 which, in about ten minutes, will render the surface of the eye 

 insensible to pain, for several minutes. 



Amaurosis, or Glass Eye, 



is not a disease of the eye itself; but is the condition of an eye 

 in which there is loss of function of the optic nerve, which form 

 of paralysis renders the retina insensible to the action of light. It 

 may be due to some affection of this nerve, or to sympathetic causes. 

 If it be owing to the former, it will be incurable ; if to the latter, 

 it will probably disappear when the original disease is relieved. 

 The functions of the 'Optic nerve may become arrested by pressure 

 on it from tumours in the brain, or by the loss of its blood-supply 

 from the blocking up of the small artery which is in the centre of 

 this nerve. A blow, a sudden shock, or a flash of lightning close to 

 the eye may, also, render it amaurotic. 



In the majority of oases, both eyes are affected. The presence 

 of the disease can be known by the fact of the pupil remaining 



