Cherry eye in cats occurs when the tear duct gland in the third eyelid becomes prolapsed, or slips out of position. Cherry eye can happen in one or both eyes. This condition is less common in cats than in dogs.
Causes of Cherry Eye in Cats
Vets don't really know what causes most cases of cherry eye in cats, though they believe there may be some hereditary component to the illness. Vets believe that a weakness in the connective tissues, or ligaments, of the eye may be responsible for allowing the tear duct of the third eyelid to slip out of its proper place. While many cases of cherry eye in cats occur without identifiable cause, this condition can also occur as a result of inflammation or infection of the eye.
Symptoms and Diagnosis of Feline Cherry Eye
The most visible sign of feline cherry eye is an ovular, red or pink mass protruding from the corner of the eye closest to the nose. This is your cat's tear duct, and when it slips out of place it can become irritated due to exposure to dust and debris.
If your cat develops cherry eye, his ocular discharge could be watery and clear or thick and mucousy, depending on whether his cherry eye has occurred due to an infection or due to weakness in the ligaments of the eye. The lining of your cat's eyelid, or conjunctiva, may become irritated, red, swollen and inflamed.
Your vet can diagnose cherry eye by performing a veterinary eye exam. Your vet will measure your cat's level of tear production in the affected duct, and he'll examine your cat's cornea for damage. He'll also take a look at the other eye, even if it isn't affected, to check for signs of impending gland prolapse or eye infection there.
Treating Feline Cherry Eye
Your vet may prescribe topical steroid medication to treat the inflammation in your cat's eye. In rare cases, topical steroids can reduce the inflammation in the tear duct and allow the gland to return to its normal position.
However, in most cases, your cat will need surgery to help move the gland back to its original position. In most cases, your vet will try to surgically replace or repair the prolapsed gland. While the gland may be entirely removed, removal significantly reduces your cat's ability to produce natural tears. If your cat has his tear duct or ducts removed, he'll suffer from dry eye for the rest of his life.
Surgery to replace or repair the prolapsed gland is usually successful. Cherry eye recurs in 5 to 20% of cases. The more quickly your cat receives the surgery after symptoms begin, the more likely surgery is to be successful.
If your cat undergoes surgery for cherry eye in one eye, keep a close watch on the other eye for signs of gland prolapse. Your cat's tear duct may not function normally after surgery, so watch for signs of dry eye including irritation of the conjunctiva, corneal cloudiness or thick, opaque discharge.