Corneal Sequestrum in Cats

Persian, Himalayan, and Burmese breeds have a higher chance of developing this condition. However, male and female cats of all breeds and ages can develop corneal sequestration.

A corneal sequestrum is a piece of dead corneal tissue, which appears as a dark brown or black spot in the eye. The spot forms as a result of the deterioration of the stroma, the primary supportive layer of the cornea. Corneal sequestra may vary in size and shape, and may also cause ulcers. Chances of total vision loss – or, in severe cases, loss of the eye – are increased if the sequestrum is large and extends deep within corneal tissue.

Corneal sequestra should be treated as a veterinary emergency, as they can cause pain and loss of vision. Seek immediate veterinary attention if you notice any of the following symptoms:

• Dark scab-like tissue in the eye
• Rubbing at the eyes
• Excess tear production
• Signs of pain
• Squinting
• Discharge
• The appearance of ulcers
• Signs of impaired vision
• Behavioral changes

The causes of corneal sequestrum in cats, while not fully understood, typically involve chronic corneal irritation. This may be attributed to trauma or dry eye syndrome. Corneal sequestrum may also be caused by the feline herpesvirus.

Genetics may play a role in the development of the condition. Brachycephalic breeds – characterized by their broad skull shapes – have a higher chance of developing corneal sequestrum due to congenital factors such as decreased tear production and corneal sensation.

Your vet will make a tentative diagnosis based on a thorough physical examination, a complete medical history, and presentation of symptoms. Be sure to inform your vet of the extent and duration of your cat’s symptoms, as well as any previous eye conditions or traumatic injuries that you know of. Your vet can normally make a tentative diagnosis based on presentation of symptoms, particularly the presence of the dark spot on the cornea.

In some mild cases, the eye may try to eject the sequestrum on its own, and drug therapy may be prescribed to assist in this process. However, corneal sequestrum treated solely with drug therapy has a higher chance of recurring, and will cause more pain and a prolonged recovery period for your cat.

While certain medications may help manage corneal sequestrum, surgery is usually favored as the most effective course of treatment. The surgical procedure is known as a keratectomy. Your cat will be placed under general anesthesia and the sequestrum removed using an operating microscope. Depending on the depth of the sequestrum, a graft of conjunctival tissue may also be applied over the surgery site to provide additional protection and assist healing. Corneal transplant may be recommended as an alternative to grafting.

Following surgery, your cat will be given an Elizabethan collar to prevent it from irritating the surgery site. Your vet will also prescribe an antibiotic ointment for up to ten days following surgery. If your cat has a decreased tear production, artificial tear supplements may be prescribed long-term. Pain management medications and oral antibiotics may also be prescribed. Your vet will be able to advise you on a treatment and recovery plan based on your cat’s specific needs.

Recovery and prognosis will depend on the severity of the condition and the effectiveness of treatment. In most straightforward cases of corneal sequestrum in cats, keratectomy has a high success rate. Most cats make a full recovery within six months of treatment. The placement of a graft may slightly reduce your cat’s vision, but the vision of the affected eye typically remains functional. In fact, vision should improve following surgery.

Always follow your vet’s post-operative instructions carefully. It is imperative that you administer antibiotic medications for the entire recommended duration of treatment even if the condition starts to improve. Failure to do so could result in aggressive recurrence or loss of sight. Never use any eye drops or artificial tear supplements made exclusively for human use unless specifically instructed by your vet.

Ensure your cat has a warm, safe place to rest upon returning home. Your cat will be sore after the surgery, and may keep the affected eye partially or fully closed for a few days. This is normal. Keep the Elizabethan collar secured until the surgery site has completely healed. Your vet may recommend that you carefully clean the affected eye up to twice a day with a wet cotton ball.

Your vet may schedule follow-up appointments as needed to monitor your cat’s progress. If you have any questions regarding aftercare, ask your vet. If the sequestrum recurs, or if your cat sustains a new eye injury following treatment, contact your vet immediately.