Surgical options for feline corneal sequestrum By Dr Anu O’Reilly for Animal Eye Care Corneal sequestrums are black or brown lesions that develops o

Surgical options for feline corneal sequestrum

By Dr Anu O’Reilly for Animal Eye Care

sequestrum

Corneal sequestrums are black or brown lesions that develops on the cornea. It may or may not be associated with corneal vascularisation. It is a condition unique to cats and can occur in any breed or age of cat. It is especially common in the Persian, Himalayan, Colourpoint, Abyssinian and Burmese.

Feline corneal sequestrum may develop without any obvious cause. It is especially common in purebred cats. A sequestrum may also follow viral infections e.g. cat flu (Feline Herpesvirus), corneal ulcers, or result from corneal irritation.

There are three surgical options for treating corneal sequestrums.

Superficial Keratectomy
A superficial keratectomy involves separating the diseased surface layers from the normal underlying cornea. A corneal disc knife is used to glide between the individual corneal layers so that a clean margin is attained. Failure to attain a clean margin results in sequestrum recurrence. After the keratectomy is performed either a third eyelid flap or a temporary tarrsorrhaphy are placed to protect the cornea whilst it is healing.

pedicle

Conjunctival Pedicle Flap
A conjunctival pedicle flap is used for patients with deep sequestrums or patients that are predisposed to recurrence. These patients include those under the age of 8 years and Persians. Firstly a keratectomy is used to remove the diseased cornea. Then a thin tongue of conjunctiva is dissected off the sclera and sutured directly onto the cornea using 8-0 or 9-0 suture material. As with a superficial keratectomy a temporary tarrsorraphy is placed.

slidinggraft

Clear Corneal-Conjunctival Transposition
For certain cases a clear corneal-conjunctival transposition can be used to treat deep cases and those prone to recurrence. Firstly a keratectomy is performed to remove the diseased cornea. Then a section of adjacent normal cornea is undermined to the limbus and into the conjunctiva. This entire section is then transposed over and onto the keratectomy site. The transposed tissue is then sutured down onto the cornea and a temporary tarrsorrhaphy is placed.

Prognosis
Conjunctival pedicle grafts and clear corneal-conjunctival transposition appear to prevent the recurrence of sequestrums. There is a 5% chance that a conjunctival pedicle graft may dehisce (contract and pull out due to poor blood supply).

Post Operative Care
1. Doxycycline e.g. Vibravet® antibiotics are used postoperatively in the form of tablets or paste.
2. An Elizabethan collar may be required if the animal tries to scratch their eye.

Following surgery it is possible for unusual reactions to develop on the cornea. These may include corneal scarring and eosinophilic keratitis. These complications are unpredictable and may require prolonged therapy.

We may need to use drops and or tablets after surgery to help reduce any reaction that may already be present or may develop in the cornea after the surgery.

Please contact the clinic if you have any questions or concerns regarding corneal sequestrum.

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