Causes of Cherry Eye in Cats
Cherry eye is fairly rare in domestic cats. When it does occur, it involves eversion or prolapse of the gland of one or both of the cat’s third eyelids (also called the nictitating membranes). Those glands are intimately associated with and located underneath the third eyelid, and usually they can’t be seen. They normally contribute up to fifty percent of the soothing, lubricating liquid that makes up a cat’s tears. Tear film is important to protect the cornea and other eye structures and to keep the eye surface moist. When the gland of the third eyelid becomes exposed, it no longer produces and secretes its normal contributions to tear film. What actually causes the gland to flip over and pop out at the inner corner of the affected eye is not well-understood. Many authorities believe that cherry eye happens as a result of some weakness in the fibrous connective tissues that are supposed to firmly anchor the third eyelid/nictitating membrane to the cat’s eyeball (also known as the periorbita or globe of the eye). This weakness may have a hereditary component, and it may or may not be congenital (which means that it may or may not exist at the time the cat is born).
Preventing Cherry Eye in Cats
At the present time, there are no reported medical or surgical procedures that can prevent the occurrence of cherry eye in cats (or in other companion animals) without the risk of serious adverse side effects. Certainly, the gland of the third eyelid can be surgically removed, which used to be the recommended treatment protocol. However, because that gland is responsible for producing so much of a cat’s tear film, taking it out markedly increases the animal’s risk of developing “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 the pain and discomfort accompanying the dry eye condition. Surgical correction by repositioning and permanently suturing the third eyelid to underlying tissue is the current treatment of choice for cats with cherry eye and is the best way to prevent repeated incidents. Many cats will have to go through a series of surgical procedures to fix the problem, in one eye at a time.
If an owner thinks that her cat may have developed cherry eye in one or both eyes, she should take it to the veterinarian as soon as possible. This condition can be uncomfortable and become painful as the gland of the third eyelid starts drying out and tear production is compromised. Any unusual discharge coming from the affected eye or eyes can be gently removed with a soft tissue moistened with warm water.