Page 1174 - Problem-Based Feline Medicine

1166 PART 15 CAT WITH EYE PROBLEMS

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WHAT?
● Blindness caused by opacity of the ocular media is discussed in the chapters headed “The Cat
With a Cloudy Eye” and “The Cat With a Red Eye”.
● Blindness in cats usually occurs secondary to systemic disease. Toxoplasmosis, cryptococcosis
and systemic hypertension are the most common causes. Less common causes include glau-
coma, taurine deficiency and central nervous disease.

QUICK REFERENCE SUMMARY
Diseases causing retinal disease
WHERE?
RETINA
DEGENERATIVE

● Hereditary retinal degeneration in Abyssinian cats (p 1183)
This is a genetically determined progressive retinal degeneration that is rare in other breeds of cats.
Young cats (< 4 years) present with loss of vision. Fundoscopy reveals a hyper-reflective tapetum
and attenuated retinal blood vessels.
● Feline central retinal degeneration (p 1181)
This is likely to be an early stage of taurine deficiency retinopathy. See Taurine deficiency below.
METABOLIC
● Hypertensive retinopathy*** (p 1171)
Relatively common in older cats. Cats present with sudden blindness, and may have a dilated
pupil(s) (usually bilateral) with a red vitreous, resulting from retinal hemorrhage. Retinal detach-
ment is common. Early cases may show hemorrhage along the larger retinal blood vessels. Check
renal function, thyroid function and the heart for cardiomegaly.
● Anemic retinopathy (p 1186)
Loss of pupil light reflexes and pale retinal vessels and small hemorrhages throughout the retina.
Occurs in severely anemic cats with PCV < 10% or hemaglobin levels below 5 g/dl. Other signs of
severe anemia are present.
● Hyperviscosity syndrome (p 1186)
Cats with marked hyperproteinemia may show retinal hemorrhage, optic disc swelling and partial
retinal detachment secondary to retinal hypoxia. Most commonly occurs associated with multiple
myeloma.
● Lipemia retinalis (p 1185)
Rare in cats. Retinal blood vessels appear enlarged, with a yellow to orange hue. Although most are
idiopathic, it is also seen in cats with diabetes mellitus, inherited hyperchylomicronemia and follow-
ing high doses of corticosteroid administration.
MECHANICAL

● Glaucoma causing retinal degeneration (p 1178)
Cats that have advanced glaucomatous retinal changes usually have buphthalmos (enlarged globe).
There is a high intra-ocular pressure above 30 mmHg. The retina may be hyper-reflective with