Ophthalmology Corneal
Sequestrum
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What is a corneal sequestrum?
A sequestrum presents as a brown/black lesion on the corneal surface. In their early stages, the corneal sequestrum may not cause pain or visual impairment, however with time, corneal ulceration is likely to develop and the cat will show intermittent signs of eye pain such as blinking, squinting, weeping and light sensitivity. If the sequestrum erodes deeply, or the ulcerated area becomes infected, there is a risk of perforation and potential loss of the eye.
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What causes a corneal sequestrum to form?
Sequestra are predominantly seen in cats. It is not currently known why they form, however, certain risks factors for development have been identified e.g. brachycephalic breeds, chronic corneal ulcers, entropion and feline herpesvirus.
How are they treated?
Each patient is assessed individually, and the ophthalmologist will discuss viable treatment options with you.
Medical management is only suitable for non-painful, superficial sequestrums. Rarely, they can shed naturally and resolve with medical management only. Eye drops will be prescribed to help support the cornea. However, this route can be unpredictable and unsuitable for every patient depending on the severity of the sequestrum.
Surgical treatment involves the removal of the sequestrum under a general anaesthetic. The depth of the sequestrum cannot be fully assessed until the surgery is underway, so the ophthalmologist will decide the best surgical technique once under the operating microscope. For deeper sequestrums, it is usually necessary to also perform a corneal grafting procedure.
What happens after surgery?
Following surgery, the patient will need to wear a buster collar and stay indoors until advised by the surgeon, this is to prevent damage to the eye by rubbing or scratching.
Antibiotic drops, lubricants and pain relief will be prescribed for approximately 14-21 days, or longer if necessary. For some patients, lubricating eye drops may be recommended for long-term use to help provide additional corneal protection.