KERATITIS (CORNEITIS).

This is an inflammation of the cornea proper, although the sclerotic at the
corneal border becomes involved to some extent. It may be divided into
diffuse and suppurative.

_Causes._--The cornea constitutes the most prominent portion of the
eyeball, hence it is subject to a variety of injuries--scratches, pricks,
contusions, lacerations, etc. Inflammation of the cornea may also be due to
the extension of catarrhal conjunctivitis or intraocular disease, and it
may occasionally occur without any perceptible cause.

_Symptoms._--Diffuse keratitis is characterized by an exudation into and an
opacity of the cornea. The swelling of the anterior part of the eyeball may
be of an irregular form, in points resembling small bladders, or it may
commence at the periphery of the cornea by an abrupt thickening, which
gradually diminishes as it approaches the center. If the whole cornea is
affected, it has a uniform gray or grayish-white appearance. The flow of
tears is not so marked as in conjunctivitis, nor is the suffering so acute,
though both conditions often exist together. Both eyes usually become
affected, unless it is caused by an external injury.

In favorable cases the exudate within the cornea begins to disappear within
a week or 10 days, the eye becomes clearer and regains its transparency,
until it eventually is fully restored. In unfavorable cases blood vessels
form and are seen to traverse the affected part from periphery to center,
vision becomes entirely lost, and permanent opacity (albugo or leucoma)
remains. When it arises from constitutional causes recurrence is frequent,
leaving the corneal membrane more cloudy after each attack, until the sight
is permanently lost.

Suppurative keratitis may be a sequel of diffuse keratitis; more commonly,
however, it abruptly becomes manifest by a raised swelling on or near the
center of the cornea that very soon assumes a yellow, turbid color, while
the periphery of the swelling fades into an opaque ring. Suppurative
keratitis is seldom noticed for the first day or two--not until distinct
pus formation has occurred. When it is the result of diffuse keratitis,
ulceration and the escape of the contained pus is inevitable; otherwise the
pus may be absorbed. When the deeper membranes covering the anterior
chamber of the eye become involved, the contents of this chamber may be
evacuated and the sight permanently lost.

_Treatment._--Place the animal