A corneal sequestrum is a condition most commonly affecting cats although, rarely, it can affect dogs too. The characteristic appearance of the sequestrum is that of a dark brown to black area developing over the surface of the eye (cornea).
A corneal sequestrum can range from just a few millimetres to cover almost the whole of the surface of the eye, leading to visual impairment. In the majority of the cases, discomfort and pain are seen alongside the dark discolouration of the eye.
What is a corneal sequestrum
Diagnosing a corneal sequestrum is, in most cases, straightforward due to its characteristic appearance; however, in some cases, foreign bodies (such as plant material) can cause confusion and be mistakenly diagnosed as a sequestrum.
A corneal sequestrum is defined as a necrotic (which means “dead”) part of the cornea. They usually develop due to chronic irritation of the surface of the eye or long-lasting injuries, such as entropion or corneal ulcers. Unlike ulcers developing in a dog’s eye, ulcers in cat’s eyes are more likely to turn to sequestrums if not treated appropriately.
Certain breeds of cats such as Persians, Siamese and Burmese are predisposed to developing a corneal sequestrum. In addition, cats with brachycephalic head conformation are also predisposed to the condition. In contrast with corneal foreign bodies, corneal sequestrums are well adhered and “stuck” to the surface of the eye and cannot be removed or flushed away from the eye.
Because of the fact that a corneal sequestrum is part of the patient’s cornea, removing it without surgery is extremely challenging and, in most cases, not possible. Although your pet’s health is not associated with the formation of a sequestrum or the likelihood to develop a sequestrum, conditions like “cat flu” (in which feline herpes virus plays an important role) can affect or be associated with the development of the sequestrum.
Can a corneal sequestrum heal on its own?
Most corneal sequestrums require surgical removal for complete and rapid resolution of the problem. Surgery has the highest success rate and the highest chance to remove the sequestrum completely, which means that the likelihood of recurrence of the problem is limited.
Unfortunately, corneal sequestrums cannot heal on their own. Most, especially when they are long-standing, grow very deep into the cornea and require surgical removal in combination with a corneal graft to ensure the eye will heal uneventfully after the procedure.
In a very small proportion of cases, and only when the sequestrum is very superficial (as identified via a veterinary ophthalmologist with the appropriate equipment and expertise), a combination of different drops and ointments can help the resolution of some sequestrums without surgery. However, if at all possible, this is a process that can take a very long time (usually months) during which your cat will need to receive medication and have multiple recheck appointments with a veterinary ophthalmologist.
How long does a corneal sequestrum take to heal?
Healing of the sequestrum, or rather, healing of the cornea, depends on the technique used to remove the sequestrum. For cases that undergo surgical removal without the need for a corneal graft, the eye returns to normal within a period for 7-10 days.
If the sequestrum is growing deep into the surface of the eye and a corneal graft is required, healing of the cornea after the surgery usually takes 2-3 weeks. Scarring can develop after these surgeries but, eventually, the scar fades away and vision is rarely affected.
In contrast to surgery, trying to treat a corneal sequestrum with drops and topical medication can take months (3-4 months, or longer) during which period the cat has to be confined indoors. The stress of long-term medication and indoor restriction can be stressful for some cats and be counterproductive for the healing of the eye.
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Frequently Asked Questions (FAQs)
1. Is it safe to delay surgery and try medical management first?
For some corneal sequestrums, this might be a sensible option. However, the plan of action and deciding if your cat is a candidate for medical treatment is based on assessment of the extent of the sequestrum by a veterinary ophthalmologist
2. Will my pet regain normal vision after treatment?
In most cases and especially when the problem is recognised and treated early, full recovery of vision is expected