544 
DEPARTMENT OF SURGERY. 
GO Dislocation of Lens. —The changes in the position of 
the lens may be acquired by concussion or compression. The lens 
is held in position by the zonula of Zinn, and its displacement 
is made possible by the rupture or relaxation of its fibres, 
which usually results from injury to eyeball by concussion or 
compression, that forces the aqueous humor against the lens. 
The displacement may be partial or complete, the lens may be 
forced into the vitreous humor or into the anterior chamber of 
the eye ; when the zonula is only partially ruptured, it may be 
thrown into the pupil and held in that position by the sphincter 
of the iris; and, when the sclera is ruptured, it may be lodged 
under the conjunctiva or Tenon’s capsule. In veterinary prac¬ 
tice, the surgical treatment of dislocation of lens is not a very 
valuable procedure ; if located under the conjunctiva it can 
easily be removed, but the advantages gained from such inter¬ 
ference does not increase the appearance or usefulness of the 
patient ; in fact, surgical intervention should not be attempted 
unless complications indicate undesirable sequelae. 
II. Rupture of Eyebaul. —Ruptures of the eyeball are 
partial or complete. In partial rupture of the sclera the inner 
fibres are torn and the outer ones are only stretched. Such in¬ 
juries are usually accompanied by intraocular lesions. Complete 
rupture of the sclera is not a common occurrence, but when rup¬ 
tured, the wound is generally in the anterior part of the sclera 
between the cornea and Tenon’s capsule and above the cornea. 
The prognosis in ruptures of the eyeball is never very favor¬ 
able ; the iris may adhere to the cicatrix ; the eyeball may 
atrophy or shrink from the loss of humors ; extensive intraocu¬ 
lar haemorrhage is often followed by inflammatory reaction ; and, 
partial ruptures of sclera may never reunite, and be followed 
later on, by the development of scleral staphyloma. Only in 
very rare cases is the vision unimpaired. The treatment in 
most cases is confined to the external wound ; while in severe 
injuries of this kind enucleation or evisceration is indicated. 
III. Abscesses are very uncommon conditions in domestic 
animals ; they may occur in the cornea, sclera or conjunctiva. 
Those of the cornea are generally sequelae of other pathological 
conditions, which are usually traumatic or infectious ; those of 
•the sclera are very rare, and when they do occur, they result 
from traumatic injuries ; they are seldom, if ever idiopathic ; and 
those of the conjunctiva are more common than either of the 
% above mentioned abscesses ; however, the palpebral conjunctiva 
is more susceptible than the ocular. 
