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Feline corneal sequestrum
Corneal sequestrum is a lesion specific to cats: an area of the cornea dies and takes on a color ranging from honey to dark brown, sometimes almost black. This plaque, clearly visible on the transparent window of the eye, corresponds to n...
What is it?
Corneal sequestrum is a lesion specific to cats: an area of the cornea dies and takes on a color ranging from honey to dark brown, sometimes almost black.
This plaque, clearly visible on the transparent window of the eye, corresponds to necrotic tissue that the body slowly seeks to eliminate.
The progression is often slow, over several weeks or months, but the eye remains painful as long as the lesion is present.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Brown, amber or black spot in the center or periphery of the cornea, which darkens over time.
Eye half-closed, frequent blinking.
Persistent tearing, sometimes tinged by secretions.
Redness of the white of the eye and development of small vessels which progress towards the spot: this is a sign that the body is working to eliminate the dead zone.
Variable pain, sometimes discreet: some cats seem to get used to it and only show moderate discomfort.
In advanced forms, the plate can break away and leave a deep crater.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The mechanism is chronic suffering of the cornea, the origin of which can be multiple.
Feline herpesvirus infection is a frequently found factor.
Any prolonged irritation contributes to this: ulcer that does not heal, hairs that rub, poorly positioned eyelid, eye that closes poorly or lacks tears.
In flat-faced breeds, the protrusion of the globe and incomplete blinking expose the central part of the cornea to dryness.
The exact causes are not all elucidated and several factors often combine in the same cat.
Flat-faced breeds, particularly the Persian, Exotic Shorthair and Himalayan; Burmese and Siamese cats are also described as subjects.
Cats carrying feline herpesvirus.
History of prolonged or recurrent corneal ulcer.
Eyelid abnormalities and lack of tear production.
Sequestration already occurred in the other eye.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The diagnosis is largely based on the characteristic appearance of the lesion, which a veterinarian recognizes on examination.
The fluorescein test specifies whether the surface around the plaque is ulcerated and assesses the depth.
Tear production is measured and the eyelids are examined for friction.
Testing for herpesvirus is useful when the cat has an ocular or respiratory history.
Regular check-ups make it possible to monitor progress: some superficial lesions disappear spontaneously, others become deeper.
Treatment
Two routes exist and the choice is made on a case-by-case basis with the veterinarian.
Medical follow-up may be offered for superficial and not very painful lesions: local care, antiviral if the herpesvirus is the cause, analgesics, protection of the cornea and close monitoring.
Surgical removal of the necrotic area is the most reliable solution for deep or very painful lesions; it is often supplemented by a graft intended to strengthen the cornea.
A collar is necessary to prevent the cat from making the lesion worse.
Eye drops containing a corticosteroid should be avoided without warning, as the cornea is weakened.
Treatment of contributing factors, such as a lack of tears or eyelid rubbing, is an integral part of the treatment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Treat any corneal ulcer without delay and follow the controls until complete healing.
Monitor the eyes of predisposed breeds closely and report any spots, even small ones.
Manage herpesvirus episodes and limit the stress that triggers them.
Surgically correct eyelid abnormalities that rub on the eye.
Maintain lubrication of the eye when a lack of tears is diagnosed.
Possible complications
Progressive deepening of the lesion, possibly leading to perforation of the cornea.
Infection of the injured area.
Permanent scar leaving an opacity disturbing the vision.
Recurrence in the same eye or appearance of sequestration in the other eye.
When to see a veterinarian
A brown or black spot appears on the surface of your cat's eye.
The eye is painful, watery or remains half-closed.
The spot grows, darkens, or deepens.
Red vessels progress on the cornea.
The lesion detaches and leaves a crater: consult the same day.
Your cat rubs its eye repeatedly.
Prognosis
The visual prognosis is generally good when the lesion is treated before reaching the deeper layers.
After surgery, most cats have a comfortable eye, sometimes with a residual scar.
Recurrences are possible, particularly in predisposed breeds and in cats carrying the herpesvirus, which justifies long-term monitoring of both eyes.
Frequently asked questions
Is this black spot dirt on the eye?
No, it is not removed by cleaning: it is an area of the cornea itself which has become necrotic. Any dark spots that appear on a cat's eye should be shown to a veterinarian.
Is it necessary to operate?
No. Superficial lesions can be monitored medically. Surgery is especially necessary when the lesion is deep, painful or does not progress favorably.
Is my cat in pain even though he eats and plays normally?
It's possible: the cat masks chronic pain very well. Tearing, blinking and withdrawing are more reliable clues than appetite.
Is the second eye likely to be affected?
Yes, especially in predisposed breeds. An examination of both eyes is carried out at each check.
References
AAFP — American Association of Feline Practitioners
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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