Page 1253 - Problem-Based Feline Medicine

60 – THE CAT WITH ABNORMALITIES CONFINED TO THE CORNEA 1245

Cats with acute uveitis need to be worked up for sys- The conjunctiva is usually involved secondary to the
temic diseases. The most common rule outs are toxo- cornea, and may present with a similar white, prolif-
plasmosis, cryptococcosis, FeLV, FIV, FIP (in young erative plaque and mucopurulent ocular discharge.
cats) and systemic mycoses in North America.
The third eyelid may also show proliferative lesions.
There is often a history of a poor response to a vari-
EOSINOPHILIC KERATITIS*
ety of antibacterial agents.
Classical signs
Diagnosis
● Irregular white to pinkish plaque on the
cornea. There is usually a history of an edematous, vascular-
● Corneal edema and vascularization. ized cornea that will not respond to antibiotic therapy.
● +/- Similar conjunctival lesion.
● Unilateral or bilateral. Clean the eye with saline or eye wash, and take a scrap-
● Poor response to a variety of antibacterial ing of the lesion using a scalpel blade, spatula or cytol-
agents. ogy brush. Gently spread the tissue onto a glass
microscope slide and stain with a Wright or Romanofski
stain. The presence of eosinophils is diagnostic. If
Pathogenesis conjunctival lesions are present, preferably take a sam-
ple from the conjunctiva.
The disease is thought to be immune-mediated or an
allergic response peculiar to cats. The use of cytology brushes on the cornea and con-
junctiva will give the best results for examination of
There is no age, sex or breed predisposition.
cell structure.
Eosinophilic keratitis is a proliferative lesion with an
Small conjunctival biopsies can be submitted in for-
intense infiltration of inflammatory cells including
malin for histopathology. The presence of eosinophils
plasma cells, lymphocytes, eosinophils and occasional
is diagnostic. These may be easily taken by applying
histiocytes and mast cells. The corneal stroma shows
local anesthetic (preferably proxymetacaine) in the eye,
edema and intense vascularization, both superficial and
and removing a small snip of conjunctiva from under
deep.
the upper or lower eyelid with a fine pair of forceps and
Insect bites from (insects) and food allergies have scissors.
been documented as causes of this condition. It has also
Hematology may reveal a peripheral eosinophilia.
been suggested that this response may be an ocular
form of the “Eosinophylic granuloma disease com-
plex”, particuarly the linear granuloma response. See
The Cat With Salivation (page 586). Differential diagnosis
Chronic ulcerative conjunctivitis.
Clinical signs ● Ulcers that heal with proliferative granulation tissue
are rare in the cat. However, chronic ulcers may
Signs begin unilaterally, but may become bilateral.
present with intense vascularization and granulation
Seen as a cloudy, red cornea. This is a proliferative of the stroma.
lesion producing whitish to pink, plaque-like tissue ● Eosinophils will not be present in cytology of such
that may be covered by a thick white discharge. lesions.
The corneal epithelium is usually intact, but may show Keratomalacia (melting cornea).
patchy staining with fluorescein. There is usually an ● This is usually an acute corneal problem with
intense neovascularization (superficial and deep) in severe edema and loss of stromal tissue forming a
chronic cases. There is varying degrees of edema, usu- deep extensive ulcer. There is rarely vasculariza-
ally involving the entire cornea. tion. These lesions may be infected with