Filaria oculi (provisionally taken as the larva of F. cervina) is a small white worm, found swimming in the aqueous fluid in the anterior chamber. It may be apparently harmless for a long time, but will eventually induce keratitis with inflammatory exudations.
Treatment.—The cornea may be punctured at its upper and outer margin, and the worm squeezed out with the aqueous humor. The latter will be formed again. This operation results disastrously unless the greatest care and skill are employed.
CORNEAL DERMATOMA (HAIRY TUMOR ON THE EYEBALL).
In a few instances this has been seen as a congenital growth. The tumor arises from the cornea or the sclerotic, covered by its respective membrane, with a growth of hair upon its surface. These tumors may be quite prominent or flattened, and are dark in color; the hair may protrude between the eyelids, giving the animal the appearance of having a double eyelid.
Treatment.—A surgical operation becomes necessary for their removal— one requiring a skilled operator.
STRABISMUS (SQUINTING).
This is a very rare affection among cattle. Strabismus may be either single or double—affecting one eye or both. It is caused by a paralysis, or a weakening of one of the straight muscles of the eyeball. Generally it is a congenital defect, and the squinting is toward the nose—strabismus convergens. It is best not to attempt to remedy the defect, as the risk in an operation is greater than the chances of success warrant.
PTERYGIUM.
This term is applied to a flesh-colored membrane, triangular in form, which most frequently grows from the inner angle of the eye and extends over the cornea, thus interfering with vision. It may grow from the outer angle, or even from either the superior or inferior hemisphere of the eyeball. The figure is invariably that of a triangle, with its base on the white of the eye and its apex more or less advanced over the cornea toward its center.
The distinguishing characteristics are the constancy of the triangular form, and the facility with which the whole of it may be taken hold of with a pair of forceps and raised into a fold on the cornea. Every other kind of excrescence attached to this membrane continues firmly adherent to it, and can not be folded and raised from the surface of the cornea in any manner whatever.