Corneal sequestration is a condition of unknown etiology that is unique to the cat’s eye. It appears as an island of dark brown to black necrotic (dead) material on the cornea. Although the underlying cause is uncertain, it is known that the lesion occurs after a history of chronic corneal irritation or ulcers; particularly as a complication of feline herpes virus keratitis. It may occur in any breed of cat but Persian, Himalayan, Siamese, Birman and Burmese breeds are predisposed to developing this condition. A corneal sequestration causes variable levels of discomfort and hinders normal vision. Usually, only one eye is affected, but the condition can be bilateral in cats with a breed predisposition.

Cat with corneal sequestrum

Diagnosis is made based on clinical appearance after a comprehensive physical examination to exclude complicating factors such as tear film abnormalities, absence of the third eyelid, and infection.

Clinical signs:

• Squinting or excessive blinking
• Dark discharge at the inner corner of the eye and around the eyelids
• Firm tan to dark brown/black lesion in the center of the cornea
• Corneal vascularization

Treatment involves determining and removing the source of irritation, enhancing lubrication, and preventing secondary infection. Specific treatment depends on the depth and painfulness of the lesion.

1. Conservative therapy for superficial lesions

a. Artificial tears
b. Therapeutic contact lens

(Note: Healing may take 1-6 months with conservative therapy. If the condition worsens or the cornea does not heal, surgery is recommended)

2. Surgical treatment under general anesthesia is needed for painful or deep lesions. One of the more common techniques used is called superficial keratectomy.

After healing, a very faint scar may remain. The lesion can recur, particularly in predisposed breeds. It usually does not reoccur when there is no breed predisposition.

Following surgery the prognosis is good for a pain free eye with normal vision. Cats with a predisposition may have additional lesions in the future. It is important to notify the clinic quickly if the lesion recurs.