Feline Corneal Seqeustra
What is a corneal sequestrum?
A corneal sequestrum is an area of necrotic (dead) corneal tissue and may appear as a pale ‘tea stained’ or darker brown oval-shaped lesion on the surface of your cat’s eye. Usually only one eye is affected at a time, however both eyes may be affected at some stage. Accompanying clinical signs may include blepharospasm (squinting) due to discomfort, excessive tear production, corneal ulceration and conjunctival redness.
Why do sequestra occur?
These lesions are seen most commonly in brachycephalic (shortnosed) breeds such as Persians or Exotic Short Haired cats, however Domestic Short Haired cats (moggies) are also very commonly affected. In brachycephalic breeds corneal exposure due to the inability to blink completely and corneal irritation due to concurrent entropion (rolling in of the eyelids) predisposes them to developing sequestra. They can also form in any breed due to entropion, previous ulceration or due to underlying Feline Herpes Virus-1 infection for example.
How are they treated?
Microsurgical removal of the sequestrum is the gold-standard treatment of choice and involves specialist equipment, magnification and skills to be performed. The surgical technique used varies depending upon how deep within the cornea the sequestrum extends.
- If only the top 50% of the cornea is involved the sequestrum is deemed ‘superficial’ and once removed, protective support such a contact lens is usually all that is required to protect the healing cornea and maintain ocular comfort.
- If more than 50% of the corneal tissue needs to be removed then the sequestrum is deemed ‘deep’, and structural support in the form of conjunctival or corneal grafting is required to stabilise the cornea whilst healing occurs.
How successful is surgery?
Recent scientific studies report a recurrence rate of between 10 - 15% following surgery, thus a small number of patients may require further procedures before healing is observed. Most cats however recover with excellent vision and minimal corneal scarring depending on the surgical technique required. If other abnormalities such as entropion are present for example, eyelid surgery is advised at the same time to reduce the risk of recurrence in affected patients. Treatment of other underlying conditions such as Herpes Virus is also advised to minimise recurrence in either eye, and your cat may require ongoing medication which your Ophthalmologist will discuss with you.