Cat Cherry Eye

Introduction

"Cherry eye" is an eversion of the ocular nictitating membrane (third eyelid) caused by hypertrophy and prolapse of the gland associated with that membrane. The nictitating membrane is a thin sheet of tissue that normally is well-anchored to surrounding eye tissue. When prolapsed, the third eyelid gland becomes visible and appears as a red mass bulging from the inside corner of the cat's eye.

How "Cherry Eye" Affects Cats

"Cherry eye" is rare in cats. When it does occur, the red protrusion at the inner corner of the eye usually is the only noticeable clinical sign. Redness, swelling, excessive tearing and other signs of eye irritation can also occur. "Cherry eye" can occur in one or both eyes, at the same or at different times, and usually happens quickly. The primary function of the nictitating membrane is to moisturize and physically protect the eye - particularly the cornea. The gland within that membrane produces much of the fluid that makes up tear film. When this gland is prolapsed, the eyes become red, dry, irritated and inflamed from abnormal environmental exposure and disruption of normal tear production. "Cherry eye" should be treated promptly to prevent permanent ocular complications.

Causes & Prevention

Causes of Feline "Cherry Eye"

The precise cause of "cherry eye" is not known. Some cat breeds are predisposed to prolapsed third eyelids, including the Burmese and the Persian, suggesting a genetic component. There is no known gender predisposition. It is suspected that this condition happens as a result of some hereditary or congenital weakness of the fibrous connective tissue that anchors the nictitating membrane to the periorbita (the eyeball).

Preventing "Cherry Eye" in Cats

There is no known way to prevent the occurrence of "cherry eye" in cats or in dogs. The condition typically appears suddenly and without warning. Surgical repositioning and permanent suturing of the third eyelid to underlying tissue is the best way to prevent further incidents.

Special Notes

If your cat develops what appears to be "cherry eye," consult with your veterinarian as soon as possible. If you notice any unusual ocular discharge, you can gently remove it with a soft moistened tissue.

Symptoms & Signs

"Cherry eye" is occurs when a gland associated with the cat's ocular nictitating membrane (sometimes called the third eyelid) prolapses and becomes enlarged and inflamed. The nictitating membrane is a thin sheet of tissue that normally is well-anchored to the surrounding eye tissue. When prolapsed, the gland becomes visible and appears as a red mass bulging from the inside corner of the cat's eye(s). The condition can look awful but usually can be treated successfully with medication and surgery.

Symptoms of "Cherry Eye" in Cats

"Cherry eye" is rare in cats. When it does occur, the red protrusion of tissue at the inner corner of the cat's eye often is the only noticeable sign. Redness, swelling, excessive tearing and other signs of eye irritation may also be present. "Cherry eye" can occur in both eyes at the same time (bilateral), or it can show up in just one (unilateral). In cats, as in dogs, the gland normally prolapses quickly, and owners can be shocked by the doughy red mass protruding from their cat's eye that only a few moments before appeared normal. Some cat breeds are predisposed to developing prolapsed third eyelids, including the Burmese and Persian.
If "cherry eye" is not corrected, the cat can develop additional and sometimes rather serious ocular complications. The gland within the third eyelid produces much of the fluid that makes up normal tear film. The primary function of the nictitating membrane is to moisturize and physically protect the eye - particularly the cornea. When this membrane is prolapsed, the eyes can rapidly become red, dry, irritated and inflamed from abnormal environmental exposure and insufficient tear production. There may be abnormal discharge from affected eyes as well. Some cats will rub or scratch at their eyes, which can damage the eyelids and possibly injure the cornea.
If you notice that your cat has what looks like "cherry eye," make an appointment with your veterinarian as soon as possible. This typically is not a life-threatening condition, but it should be treated promptly to prevent permanent damage to the eye.

Treatment Options

Cats and dogs both have a nictitating membrane (also called a third eyelid) that normally functions to provide physical protection to the cornea and to produce a significant portion of moisturizing tear film. Prolapse of the gland associated with the third eyelid, commonly called "cherry eye," is uncommon in cats but when it occurs should be treated as quickly as possible. "Cherry eye" is most commonly diagnosed in the Burmese and Persian feline breeds. The condition normally is not particularly dangerous to cats, but treatment is necessary to reduce the risk of more serious secondary ocular problems.

Treating "Cherry Eye" in Cats

Non-surgical options

"Cherry eye" can be treated medically with topical antibiotic and anti-inflammatory drugs and also through surgery. Topical therapy can help reduce the inflammation and possible infection commonly associated with this condition. However, this course of treatment is rarely successful permanently. If the prolapsed gland of the third eyelid does not resolve with medical treatment, surgical correction is the only viable treatment option. While repositioning the third eyelid back into place non-surgically is not a conventional treatment for "cherry eye" in cats, some veterinarians opt to try this before resorting to surgical repositioning. Repositioning the gland only takes a few minutes and apparently is painless for the cat. Unfortunately, like other non-surgical medical treatment, this technique typically is not a permanent solution, and the nictitating membrane tends to periodically re-prolapse.

Surgical options

At one time, surgical removal of the prolapsed portion of the third eyelid was the treatment of choice for "cherry eye." However, as veterinary science discovered the importance of the third eyelid gland in tear production, surgical repositioning rather than removal became the treatment of choice. The gland of the nictitating membrane contributes up to 50% of the aqueous tear fluid, and removing it markedly increases the cat's risk of developing so-called "dry eye" (keratoconjunctivitis sicca) as it ages. If the gland of the third eyelid is removed, the cat will require life-long treatment with moisturizing topical eye drops and anti-inflammatory medication to prevent severe and painful "dry eye." At least 8 different and successful surgical repositioning techniques have been reported, and the veterinarian will determine which to use in a given case. Some considerations include the ease of the procedure, its effect on future tear production, the chances of re-prolapse and the likely cosmetic results. While selection of a surgical technique is a matter of personal preference, all of the repositioning techniques, when performed properly, should result in a cosmetically acceptable outcome with a very low chance of recurrence.
If a cat has only one of its eyes affected by "cherry eye," the owner should recognize that surgical correction of the affected eye will not reduce the risk of the condition developing in the other eye. Currently, there are no medical or surgical procedures available to prevent cherry eye in companion animals, and many animals will have to go through two separate surgeries to treat one eye at a time.
If you think that your cat has developed this disorder, try not to touch or manipulate the affected area. Do not try to reposition the third eyelid, as you may permanently damage the nictitating membrane or other critical components of your cat's eye.