452 Veterinary Medicine. 



In man, excentration is sometimes substituted for enucleation, 

 the cornea is removed together with the lens, vitreous, choroid 

 and retina, leaving only the sclera which contracts into a dense 

 scar tissue with the muscles attached. Or an artificial vitreous 

 of glass or unoxidizable metal is introduced around which the 

 sclera is allowed to heal. This introduces an additional element 

 of danger over the formation of a simple sclerotic stump, but, 

 when successful, it affords a better support to the artificial eye, 

 turning it freely in harmony with its fellow and giving it a more 

 natural aspect. 



STRABISMUS. SQUINTING. I,ACK OF MUSCULAR 



BAI^ANCE. 



Causes : paralysis of eye muscles, bulb rolls from affected muscle, spasm 

 of eye muscles, bulb rolls toward affected muscle, convergent squint most 

 common. Hold head still and move object in front of eyes, imperfect 

 movement toward paretic muscle or away from the spastic one. Ptosis. 

 Overfatigue. Debility. Nerve or brain lesion. Dislocation of bulb. 

 Treatment: treat any transient etiological factor, cerebral congestion, par- 

 asitisms, debility, ansemia. Tenotomy of rectus : advance of paretic rectus. 



Strabismus may be due to a variety of causes, among others' to 

 the following : 



Paralysis of one of the ocular muscles. When the eyes are 

 turned in the direction away from the afEected muscle the muscle 

 is deficient in power. It may be the exterflal rectus (abducent 

 nerve) producing convergent squint. It may be of the superior 

 oblique muscle (4th or pathetic nerve) causing a faulty move- 

 ment of the eye downward and inward or a slightly convergent 

 squint. Divergent squint commonly indicates paralysis of up- 

 per, lower and inner recti, and the inferior oblique (3d or 

 oculo motor nerve): this is usually associated with ptosis or 

 drooping of the upper lid, the levator of which is supplied by the 

 same nerve. The existence of squint is usually so marked that 

 no special method of examination is required. If otherwise, how- 

 ever, the animal's head may be held still and some object which 

 will attract his attention is moved before the eyes, outward and 

 inward, when the affected eye moving in the direction of the 



