Page 1276 - Problem-Based Feline Medicine

1268 PART 15 CAT WITH EYE PROBLEMS

Diffuse iris melanoma typically appears as an enlarg-
CRYPTOCOCCUS NEOFORMANS
ing area over months to years of light tan to dark brown
pigmentation on the iris surface. Usually the neoplasm
Classical signs
does not form an obvious discrete mass, but the iris
may become diffusely thickened. The disease is usually ● Sudden blindness with retinal detachment.
unilateral and typically occurs in older cats. ● Vitreous flare may be present making the
● Presentation may more resemble uveal inflamma- retina difficult to examine.
tion than neoplasia. ● Anterior uveitis (anterior chamber flare,
● Sometimes the disease may present in an miosis, inflamed discolored iris).
advanced state with secondary glaucoma. ● Exophthalmos (eye bulging forward).
● Amelanotic diffuse iris melanomas have also been ● +/- Mucopurulent discharge with sneezing
reported. These are difficult to diagnose unless the and a swollen nose.
effects of the tumor on angle obstruction and result- ● Neurological signs.
ant glaucoma are observed. ● Chronic skin granulomas.
Post-traumatic sarcoma more commonly forms dis-
See the main reference on pages 1174, 16, and 1089
crete masses within the eye.
(The Blind Cat or Cat With Retinal Disease, The Cat
Ciliary body adenoma is a rare slow-growing neoplasm, With Signs of Chronic Nasal Disease and The Cat
which appears as a whitish to cream mass behind the With Non-healing Wounds).
pupil margin.
Metastatic neoplasia from an extra-ocular primary
tumor appears as an intra-ocular neoplasm involving Clinical signs
the iris, and is associated with a similar neoplasm
Cryptococcosis is the most common fungal infection
remote from the eye, e.g. mammary or uterine adeno-
affecting cats, and occurs throughout the world.
carcinoma.
The initial ocular site for establishment of infection is
usually the choroid, and the anterior uveal tract is
often involved later in the course of the infection.
Diagnosis
Cats may present with sudden blindness caused by
A tentative diagnosis is based initially on the appear-
multifocal granulomatous chorioretinitis with vary-
ance of the eye (uveitis, iris swelling and/or distor-
ing degrees of retinal detachment.
tion of the retina) and consideration of the history.
● Vitreous flare (cloudy vitreous) is present, and
Examination of the buffy coat is useful for diag- makes the retina difficult to examine in cases with
nosis of lymphosarcoma. The presence of abnormal severe inflammation.
plump lymphocytes with large prominent nucleoli is ● If the retina can be visualized, the granulomas
highly suggestive. appear as small swollen brownish discolored areas
in the tapetal and non-tapetal retina.
Biopsy of regional lymph nodes is useful if there is
lymphomegaly. There is usually anterior uveitis with corneal edema,
anterior chamber flare (with or without hypopyon and
Definitive diagnosis may be obtained by fine-needle
keratic precipitates), swollen iris with varying degrees
aspirate biopsies or anterior chamber centesis and
of posterior synechia causing a distorted pupil, and
cytology.
in chronic cases, new vascular growth on the anterior
Serology for FeLV may support the diagnosis of lym- surface of the iris (pre-iridal fibrovascular membrane
phosarcoma. formation).
Chest and abdominal radiology and/or ultrasound Complications include secondary cataract and
may be indicated. glaucoma.