CATS do not have as many eye problems as dogs do, but when an eye disease occurs in a cat, it is usually chronic and often, lifelong.
Conjunctivitis is inflammation of the pink membrane of the eye, which lines the white part (sclera) and the inner eyelid. The conjunctiva can become quite reddened and swollen in some cats, and often the problem only affects one eye. This causes intermittent or constant squinting. It can occur on and off, for months to years.
Conjunctivitis may occur without any other eye problems, or the eye may also have a corneal ulcer or erosion (painful open sore on the cornea, which is the “clear windshield” part of the eye. Corneal involvement is often caused by Feline Herpesvirus-1 (FHV-1) infection.
FHV-1 is a very common virus in cats. The virus can then be dormant in the cat’s body for the rest of the cat’s life, or flare up and cause problems at any time. Stress is a key factor in the severity of the disease and how recurrent it is. Anything that stresses the cat can suppress the immune system and allow the virus to reactivate and cause problems.
This is similar to cold sores in people, which are caused by a human herpes virus. Cold sores can worsen when the person is stressed. It is also important to know that FHV-1 conjunctivitis and corneal ulcers cannot be cured, only controlled.
In between flare-ups, the cat’s eyes can be normal. Flare-ups can occur frequently, or there can be years in between each flare-up. Some cats will never have a flare-up. Signs include squinting (which is severe if the cornea has an ulcer or erosion) and mucoid or watery discharge. The conjunctiva is reddened and sometimes swollen or thickened. The cornea can be clear, or can be cloudy if there is an ulcer, or scar tissue present.
Sometimes the cat also shows signs of an upper respiratory tract infection (URTI), such as sneezing. The URTI often precedes ocular disease. Consult your veterinarian for advice on animal health related matters.