434 Veterinary Medicine. 



junctival sac as formerly recommended, may be helpful in some 

 of the superficially opaque membranes, but for formed cataract it' 

 has proved useless. Massage with, or without ointments can 

 temporarily lessen ocular tension and reduce the liquids in the 

 zonula of Zinn, and canal of Schlemm, but it is only in very ex- 

 ceptional recent cases, in which it has given permanent benefit, 

 and even these were probably spurious cataracts. 



The question then is essentially whether we should operate or 

 not. In the horse the objections to operation are almost conclu- 

 sive in all cases. The eye in which the lens has been depressed 

 or extracted can never see objects clearly without the aid |0f bi- 

 convex glasses, and it is impossible to fit these to the animal. 



The horse that is blind can go to pasture or be driven in harness 

 with safety, but the one that sees all objects distorted or blurred 

 is liable to become a shj'er endangering the life of his rider or 

 driver. The greater number of cataracts in horses come from 

 recurrent ophthalmia and are associated with opacity of the 

 vitreous, detachment of the retina, exudates in the choroid, de- 

 generation of the optic nerve, or other lesion which of itself 

 would destroy vision. Almost the only object of removal of the 

 lens in such cases would be to make an unsound horse pass for a 

 sound one. Even this is usually unattainable because the thick- 

 ened capsule remains as a dense white cloud or the opacity of the 

 vitreous shines through the pupil. In dogs the cataract is 

 usually associated with fewer complications, and the resulting 

 imperfect vision is not a source of danger to man. Extraction 

 of the opaque lens may in this case appeal so strongly to the 

 sense of comfort of the owner that the operation may become 

 permissible or desirable. 



In man the operation may have to be delayed for a consid- 

 erable time because of the unripeness of the cataract. The 

 center of the lens may be firm and opaque while the outer layers 

 are so soft that they would be likely to be retained in the 

 capsule and would not only produce persistent opacity, but 

 would be a continual threat of destruction of the eye by active 

 inflammation. The ripeness is ascertained by careful scrutiny 

 of the shadow of the iris during illumination of the interior of 

 the eye. If ripe, the dark shadow of the iris approximates 

 closely to the margin of the iris itself, whereas if the outer 



