EYELIDS AND DRY EYE
The eyelids serve many important functions. They protect the cornea, the clear outer portion of the eye, and the eye itself from trauma. They keep light out and determine the size and shape of the opening of the eye. The eyelids also produce and spread tears over the eye. Tears supply the cornea with oxygen and nutrients; therefore they are essential to keep the cornea healthy. If the cornea is deprived of oxygen and food because of a lack of tear film, destructive changes occur quickly, leading to a condition called Dry Eye. Dry Eye is also called Keratoconjunctivitis sicca. The cornea can become pigmented, scarred, and ulcerated. Partial vision loss can also result. The eyes of cats with Dry Eye burn and sting all the time just like ours do on a windy day. Diagnosis is made by a tear test that measures how many tears the eye produces in one minute. In this case, low levels of tear production are detected.
CAUSES OF DRY EYE
1. The eyelids of newborn kittens and puppies normally open between 10 and 14 days of age. If the eyelids open too early, tears are not yet produced. Dry Eye will result unless topical eye lubricants are applied three to four times daily until tear production begins.
2. Surgical correction of the lazy eyelid prevents further damage and rupture of the eye.
3. Certain breeds including Persians, Himalayans, Burmese, and Exotic Shorthairs have very large protruding eyes, which are subject to trauma, in addition, many also have an inherited eyelid disorder called Lagophthalmos. The “lazy eyelid” or lids do not close properly and therefore can not spread the tears adequately. This increases the risk of Dry Eye and secondary Corneal Ulcers.
4. Many of these same cats also have mild Entropion of their lower eyelids. Entropion is also an inherited condition in which the eyelid tissue turns inward. This causes further irritation to the eye.
5. Chronic Herpes Virus eye infections in cats can result in Dry Eye.
TREATMENT FOR DRY EYE
* The drug Pilocarpine and the anti-cancer drug Interferon effectively stimulate tear production in certain cats.
* A surgical procedure called a Parotid Duct Transposition (PDT) is a worthwhile consideration for cases that do not respond to medication.
* With consistent therapy, most cases of Dry Eye carry a good prognosis, but without treatment, recurrent corneal ulcers, bacterial infections, and even blindness can result.
INHERITED EYE PROBLEMS
Entropion is a hereditary condition in which the eyelids roll inward which causes the eyelashes to contact the surface of the eye. This condition usually involves both eyes and is quite painful. In addition to conjunctivitis, partial or complete loss of vision can result if left untreated. Squinting and tearing are the most common signs. Persians and Himalayans seem to be at increased risk. Surgical correction involves removal of a narrow strip of skin and muscle from the eyelid. Stitches are then used to avert the eyelid so that it lies in a normal position.
2. EYELASH DISEASE
Eyelash Disease is a group of conditions in which eyelashes or hairs injure the eye.
* Trichiasis is a condition in which normal hairs lie on and irritate the eye. This is common in Persian cats. The facial hairs on the side of the eye nearest the nose can irritate the eyes and cause conjunctivitis. Prevention requires regular trimming of these hairs.
METHOD TO DETECT INHERITED EYE PROBLEMS
In addition to hereditary eyelid and eyelash diseases, several disorders of the cornea and retina are also inherited in cats. They can easily go undetected until quite advanced. CERF Exam is a method to detect Inherited Eye Problems. Most are quite painful and blindness is not an uncommon consequence. A Canine Eye Registration Foundation (CERF) examination is an eye exam that can only be performed by a certified veterinary eye specialist. It is used to detect inherited eye diseases in dogs and cats and can be given at a young age. Responsible breeders should not breed any dog or cat who fails a CERF Exam. Potential owners should ask whether or not the parents received and passed the CERF Exam. Neutering or spaying animals with these hereditary conditions insures that the problem will not be passed on to future generations.