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Corneal Sequestrum in Cats

Corneal sequestrum occurs when the cat has dead corneal tissue (or dark spots in the cornea). It usually is caused by chronic corneal ulceration, trauma, or corneal exposure. Corneal sequestrum can affect all breeds, but is more prone in Persian and Himalayan breeds. In cats, it usually begins during their middle-aged years.

Symptoms and Types

The dark spots in your cat's cornea may remain unchanged for long periods of time, and then suddenly get worse. Listed below are some other symptoms your cat may experience:

• Discoloration of the affected corneal area (in one or both eyes), ranging from a translucent golden-brown color (early stages) to an opaque black
• Chronic non-healing corneal ulcer
• Abnormal corneal cell formation, which may cause the area to swell and protrude
• Episodes of feline herpesvirus-1 (FHV-1)
• Dry eyes
• Eyelid twitches and/or ocular discharge; clear to brownish-black mucus or puss
• Blood in the outer surface of the eye and swelling
• Constriction of the pupil

Causes

The exact cause of the condition is unknown; however, the following is a list of potential risk factors:

• Chronic corneal ulceration
• Chronic irritation
• Ingrown eyelashes or entropion (eyelids fold inward)
• Shortened nose and face conformation (i.e, Persian and Himalayan breeds)
• Incomplete blink
• Dry-eye syndrome
• Tear film disorders
• Feline herpesvirus-1 infection
• Topical drug use (i.e., corticosteroids)
• Recent surgery

Diagnosis

• Corneal perforation/iris has moved — protruding iris is fleshy, and its color ranges from yellow to light brown.
• Corneal pigmentation — rare in cats
• Corneal tumor — a benign tumor occurs at the border of the cornea; it is not typically painful
• Corneal foreign body