Corneal Sequestrum

Corneal Sequestrum

By: Dr. Alexandra Van der Woerdt

Section: Overview

A corneal sequestrum is a darkly pigmented area in the cornea of the cat often associated with chronic ulcerative or inflammatory diseases of the cornea. This dark brown spot is an area of dead corneal tissue, and it may be surrounded by inflammation, blood vessels, and edema of the cornea.

A corneal sequestrum can cause chronic irritation and ulceration of the eye resulting in discomfort. Scar formation after resolution of the sequestrum may result in decreased vision. In rare cases, it may result in perforation of the eye with possible loss of vision. It usually involves one eye, although it may occur in both eyes at the same time.

Causes

  • A sequestrum can form as a result of chronic irritation and exposure of the cornea. Predisposing causes include abnormal eyelid conformation with eyelashes or hair rubbing against the cornea, inadequate tear production, corneal ulceration, and corneal infections.


  • Prior infection of the cornea with feline herpesvirus may predispose a cat to developing a corneal sequestrum.

  • Certain breeds of cats are predisposed to this disorder, including the Persian, Himalayan, and Burmese, but all types of cats may be affected.

    What to Watch For

  • Chronic squinting
  • Chronic brown or yellow-green eye discharge
  • Appearance of a black spot on the cornea (the clear part of the eye)
  • Cloudiness or redness of the eye
  • Rubbing the eye

    Diagnostic Tests

  • Thorough examination of the eye and the eyelids
  • Fluorescein staining of the eye
  • Schirmer tear test
  • Corneal scrapings for culture and detection of herpesvirus infection

    Treatment

    Corneal sequestra may be treated by two methods: with medications alone or with medications and surgery.

  • Medications alone. This method is used in those cats that do not exhibit any pain, and in which the sequestrum lesion is small and not causing much corneal inflammation. Medications include antibiotic eye ointment or solutions three to four times a day and possibly atropine ointment to improve comfort when needed. Antiviral medications are considered if an active infection with herpesvirus is suspected.

  • Medications and surgery. The removal of the sequestrum is preferred when the sequestrum is causing the cat to be painful, when the lesion is large and disrupting the surface of the cornea, or when it is causing significant inflammation of the cornea. Medications may also be used. Some cats that have had corneal sequestra require life-long medications with topical lubricant ointments to try and protect their corneas, and prevent recurrence of the condition.

    Home Care and Prevention

    Give all medications as directed. Call your veterinarian if you are having difficulty medicating your pet.

    Observe your cat for rubbing of the eye. An Elizabethan collar may be necessary to prevent further irritation of the eye.

    A warm compress applied to the eye may soothe the eye and help remove the discharge that is commonly present. Return your cat to your veterinarian if the discomfort appears to get worse.

    In some cases, use of an artificial tear ointment applied to the eyes twice a day may help to prevent recurrence of the sequestrum.

    Periodic rechecks are required to monitor corneal sequestra treated with medical therapy alone. If the lesions fail to resolve with medication, surgery may be needed. Following surgery, frequent rechecks are indicated until the cornea has healed.

     
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