Page 1257 - Problem-Based Feline Medicine

60 – THE CAT WITH ABNORMALITIES CONFINED TO THE CORNEA 1249

purple-staining cocci, free or in cells. One slide should In cases where secondary uveitis is present, systemic
also be stained with a Gram stain. Pseudomonas bacte- treatment with NSAIDs at appropriate doses and sys-
ria are seen as rods, and stain positively with a Gram temic antibiotics are recommended.
stain.
NEVER use topical corticosteroids when a corneal
ulcer is present, as this will predispose to keratomala-
Treatment cia (melting ulcer).

Infected ulcers need aggressive treatment.
Prognosis
As a general rule, frequent use of appropriate
antibiotic drops is required every 15 min to hourly for Prognosis is good in cases with simple superficial
at least 24 hours, followed by drops every 4 hours. ulcers.
Ointments can be used where there is no keratomala-
Prognosis is guarded if the entire cornea has ker-
cia, and do not need to be used as frequently.
atomalacia, or if there is hypopyon and secondary
Superficial ulcers heal rapidly and need less-frequent
uveitis.
treatment.
● When an ulcer is infected, appropriate antibiotics
should be used based on culture of a swab taken BLUNT TRAUMA
from the edge of the ulcer. If in doubt, use a broad-
spectrum antibiotic that will control both Gram- Classical signs
positive and Gram-negative bacteria.
● Painful, cloudy and red eye.
● Where a Pseudomonas infection is suspected or
● Cornea may have superficial ulcer or be
confirmed by laboratory analysis, the cat must be
ruptured (usually around the limbus).
treated vigorously with aminoglycoside (commonly
● Conjunctiva may be red from
gentomycin or tobramycin in gentomycin-resistant
subconjunctival hemorrhage.
cases) or fluoroquinalone (some generations such
● The anterior chamber may be filled with
as flucloxacillin are effective) antibiotics topically
blood (hyphema).
every 15 minutes to 1 hour until the infection is
● Eye may be bulging (exophthalmos) from
controlled. They may also be used systemically but
edema and hemorrhage in the orbit.
particular care should be used with aminoglycosides
in cats, as they are ototoxic and nephrotoxic.
Toxicity may occur from frequent topical use, so Pathogenesis
monitor cases carefully.
Blunt trauma causing corneal damage is usually the
Corneas with deep ulcers that have stromal loss need result of a motor vehicle accident.
to be protected with surgical techniques such as
third eyelid flaps or temporary tarsorrhaphies (see
Clinical signs
references for texts that show details of these surgical
techniques). The blunt trauma may cause an abrasion on the sur-
face of the cornea, usually with loss of epithelium. This
Artificial tear solutions will lubricate the eye and
is evident as positive staining with fluorescein dye.
make the cat feel more comfortable.
Rupture of the cornea may be evident, and is usually
Atropine ophthalmic drops (most commonly 1%) are
at the limbus because this appears to be the area that is
used to dilate the pupil and to prevent ciliary muscle
weakest and absorbs most of the force when the cornea
spasm. They should be used two to three times daily
is flattened inwards. The iris may protrude from the
until the pupil is dilated, and daily thereafter (NOTE:
wound and is seen as brownish pigmented tissue.
atropine drops are very bitter and often make cats sali-
vate profusely). For this reason 1% atropine ointment is Hemorrhage from iris root tears and ciliary body
often used, as the drug does not run down the tear duct trauma is common with this type of injury, and is seen
as fast. as hyphema.