Causes. Symptoms: redness of sclera, in dogs, cats, birds, pigs, with
a narrow zone of white next the cornea, red scleral vessels immovable,
iris dull gray or brown, uneven, sluggish in response to light,
synechia anterior or posterior, lens and capsule clouded or clear,
pupillary margin uneven, myosis or midriasis, black cataract.
Treatment: rest, dark stall or covering, head elevated, midriatics,
cocaine, antiseptic puncture, purgation, leeches, seton, cooling
astringent lotions, diuretics, for tension in convalescence
iridectomy. In traumatic cases careful antisepsis.
This may come from any one or more of the _causes_ of internal
ophthalmia above named. The inflammation, however, concentrates itself
on the iris so as to overshadow the disease in the adjacent organs.
The more distinctive _symptoms_ are the redness of the sclerotic in
unpigmented organs (swine, birds, dogs, cats), the redness increasing as
it approaches the margin of the cornea but leaving a narrow white zone
surrounding the edge. The red vessels on the sclerotic are not moved
with the conjunctiva when the lid is moved over the front of the eye.
The front of the iris is dull, grayish or brownish, it is thickened
unevenly and very sluggish in response to light and darkness. Not
infrequently it is adherent to the back of the cornea (synechia
anterior) or to the front of the lenticular capsule (synechia
posterior). The lens and its capsule may or may not be clouded, but if
the interior of the vitreous can be seen it is found to be clear. The
pupil is more or less uneven in outline and sometimes it is torn at its
inner edge so as to form shreds and projecting tongues. Myosis
(contraction of the pupil) or midriasis (dilatation) may be present. If
the latter has been preceded by adhesion a portion of the uvea may
remain attached to the lenticular capsule constituting =black cataract=.
The lens or its capsule may become opaque, and a fibrinous membrane may
form over the pupil.
_Treatment._ Rest for body and eye are essential. A dark stall, or a
thick covering for the eye is desirable. The head should be kept
moderately elevated to facilitate the return of blood. The pupil should
be kept widely dilated to prevent adhesions to the lens. Sulphate of
atropia 5 grs. to the oz. of water should be applied a few drops at a
time, thrice a day, or as often as may be necessary to secure
dilatation. In case the atropia fails to secure dilatation a 5 per cent.
solution of cocaine should be dropped into the eye every three or four
minutes for four or five times and then another application of atropia
may be tried warm. Should it still fail and should there be indications
of extra congestion and swelling of the iris or of excessive tension of
the eyeball, relief may be obtained by puncturing the cornea. With the
reduction of the tension the iris will often respond to the midriatic.
Benefit may also be obtained from an active purgative, or the
application of leeches in the vicinity of the eye.
Cooling astringent applications may be kept up over the eye, or warm
antiseptic applications will often give great relief.
In obstinate cases the yellow oxide of mercury ointment may be applied
as advised for _internal ophthalmia_.
Cooling diuretics may also be of essential advantage.
If, after a fair recovery the bulb remains unduly tense, iridectomy may
be resorted to as a prophylactic measure for the future. An incision is
made with a lancet close in front of the margin of the cornea, and the
iris seized and withdrawn with a pair of fine forceps, and a portion
snipped off with fine scissors. The eye and instruments must be rendered
absolutely aseptic by carbolic acid and boiling water, and the
antisepsis of the eye must be carefully maintained until the wound is
healed. This tends to relieve congestion in the iris and to moderate the
secretion in the anterior chamber, so that the former extreme tension
does not recur. In making choice of the seat of the iridectomy a
selection may be made which will do away with adhesions, or one that
will expose a portion of the lens which is still transparent, and which
may restore vision when obscured by a cataract.
In traumatic cases there should be extra care in maintaining a thorough
antisepsis of the eye as the great danger is that of infective
panophthalmitis. The injection of antiseptic liquids under the eyelids,
and the covering of the eye with antiseptic cotton wool or with a soft
rag wet with an antiseptic lotion are important factors in treatment.