Disorders and injuries may affect the structures of the eye or the eyelids, or both. All eye problems in a cat need prompt investigation by a vet, as even minor disorders can become sight-threatening if left untreated.
Conjunctivitis and eye injuries
In conjunctivitis there is swelling and redness of the conjunctiva, the membrane lining the inner eyelids and covering the front of the eyes. Common causes include irritation, allergy, or infection. There may be a clear, white, or greenish discharge. The cat may blink rapidly and rub the eye. A vet may use eye drops to clear up infection and relieve inflammation, and fit an Elizabethan collar to prevent the cat from rubbing the eye. Injury, or debris in the eye, can cause inflammation of the third eyelid and conjunctiva, or cause a bluing of the cornea at the front of the eye. A vet may use fluorescein dye to show up injury or ulceration. Treatment includes removal of debris, pain relief, and antibiotics if there is bacterial infection.
Loss of vision can be sudden (acute) or gradual. One cause of acute vision loss is glaucoma—a painful buildup of fluid inside the eyeball. The eyeball may look enlarged, with a widened pupil and clouded cornea. If not treated promptly, it could cause blindness. The vet will prescribe eye drops and tablets to lower the pressure. In older cats, acute vision loss may be due to detachment of the retina. Signs include an enlarged pupil. Gradual vision loss may be due to cataracts. These can be removed surgically, and an artificial lens may be fitted.
Other eye disorders
Corneal sequestrum particularly affects Persian, Siamese, Burmese, and Himalayan cats. A dark patch of dead tissue forms on the cornea, causing pain and excess tears. The patch can be surgically removed. Third eyelid, or haws, syndrome may result in a visible third eyelid on each eye. Possible causes include viral infection and tapeworms