Keratoconjunctivitis Sicca (KCS) in Cats

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Keratoconjunctivitis sicca (KCS) is a medical term used to describe a condition of decreased tear production. The term technically means "inflammation of the cornea and conjunctiva from drying." When the watery part of the tears is not produced in adequate amounts, the eye becomes chronically inflamed, and scarring of the cornea may lead to a decrease in vision. Another commonly used term to describe this disease is "dry eye."

The most common cause in cats is an infection of the eye with feline herpesvirus. Other causes include chronic inflammation of the conjunctiva for other reasons, a rare side effect of certain medications (such as sulfonamide drugs), removal of a prolapsed gland of the third eyelid, trauma to the tear glands, and certain neurological disorders. The disease may affect one or both eyes.

If left untreated, KCS is a potentially vision threatening disease. It may lead to painful corneal ulcerations in the acute stage of the disease. In chronic KCS, vision may be impaired because of scarring of the cornea.

What to Watch For

  • Chronic redness of the eye
  • Chronic discharge that may dry to a dark red-brown color
  • The development of a film over the eye
  • Prolapse of the third eyelid over much of the cornea

    Diagnosis

    Veterinary care includes diagnostic tests and subsequent treatment recommendations.

  • A thorough physical examination is an important part of diagnosing the cause of the KCS. The disease itself is confirmed by examination of the eye.

  • A Schirmer tear test is performed to determine the amount of watery tears produced by the eyes.

  • In addition, fluorescein staining of the eye is also performed to detect any corneal ulcers.

  • The degree of corneal cloudiness and scarring are assessed and the interior of the eye is also examined.

    Treatment

    The intensity of the treatment depends on the severity of the disease. It may include one or more of the following medications:

  • Application of 0.2% cyclosporine ointment twice a day

  • Artificial tear solution applied often during the day

  • Artificial tear ointment applied one to four times daily

  • Antibiotic ointment or drops if a corneal ulcer or infection are present

  • Antibiotic-corticosteroid drops or ointment in cases of chronic KCS

  • Topical anti-viral medications if an active infection with herpesvirus is suspected

  • Surgery rarely in unresponsive cases

    Home Care and Prevention

    Once diagnosed, home care is an important part of treatment. Keeping the eyes clean and free of discharge can be challenging. Eye discharge is common and can be very sticky and hard to remove. Applying a warm compress to the eye for a few minutes may make it easier to remove the discharge. The discharge may also be removed from the eye by carefully rinsing the eye with an irrigating eye solution that can be bought over the counter at a drug store. Some cats do not tolerate eye washes, but do accept the warm, wet compresses.

    Apply all medication as directed, and notify your veterinarian if you are having difficulty treating your pet. When treating your animal with both drops and ointment, use the drops first, followed by the ointment.

    Monitor the eye for changes such as increased discharge, squinting or redness, or if your pet starts rubbing or scratching at his eye. Notify your veterinarian immediately.

    It is difficult to prevent KCS but early treatment is crucial. It is very important to take your pet to your veterinarian when you notice persistent discharge and redness. When diagnosed early in the disease, the long-term prognosis for vision is much better than when the KCS is diagnosed in a late stage of the disease.

  • Keratoconjunctivitis sicca is an eye disease precipitated by a lack of watery tears, as described in the breakdown of the words:

    kerato- (cornea, which is the clear, transparent front of the eye)
    -conjunctiv- (conjunctiva, which the delicate membrane lining the eye)
    -itis (inflammation)
    sicca (dryness of the eye)

    So, it is an inflammation of the cornea and conjunctiva secondary to dryness of the eye.

    As the watery part of the tear film diminishes, the eye tries to compensate by making more mucousy material. In addition, inflammation of the surface of the eye also stimulates the production of more mucous.

    There are other eye diseases that may resemble keratoconjunctivitis sicca. It is important that an accurate diagnosis is made early in the disease because the treatments vary depending upon the eye disease present.

    Diseases that can appear similar to KCS include:

  • Conjunctivitis. Conjunctivitis is inflammation of the tissues that line the eyelids and cover the eye. Clinical signs of conjunctivitis include increased tearing, discharge, redness and sometimes squinting. There are many causes for conjunctivitis. (See the Client Education article on Conjunctivitis.) With most forms of conjunctivitis, the tear production is normal or high.

  • Corneal ulceration. An abrasion of the cornea causes discharge and redness of the eye. The onset is usually acute and the eye is painful. A corneal ulcer is diagnosed by applying fluorescein stain to the eye. The eye only takes up stain if ulceration is present. Corneal ulcerations may also occur as a result of KCS, especially shortly after the onset of KCS. It is important that the tear production is measured when a corneal ulcer is present. See the Client Education article on Corneal Ulceration.

  • Other forms of keratitis. In the cat, there are several forms of corneal inflammation that may appear somewhat similar to the corneal changes associated with KCS. It is believed that these disorders may also be caused by feline herpesvirus. They include eosinophilic keratitis, stromal keratitis and corneal sequestration. See the Client Education article on Corneal Sequestration.

  • Veterinary care includes diagnostic tests and subsequent treatment recommendations.

    Diagnosis In-depth

    It is important to inform your veterinarian of all the medications your cat is currently taking because KCS may be an uncommon side effect associated with some medications. Diagnosis usually includes the following:

  • Examination of the eye including a thorough evaluation of the eyelids, conjunctiva and cornea

  • Schirmer Tear Test. This test measures tear production. Normal tear production is usually more than 10 mm/min. Caution should be used when interpreting this test. When cats are stressed (such as riding in a car to the veterinary clinic), their tear production tends to decrease. This can make interpretation of low results difficult. The test may need to be repeated several times to demonstrate consistently low values (less than 5 mm/min.) in order to confirm a diagnosis of KCS.

  • Fluorescein stain. The dye is applied to the cornea to check for the presence of a corneal ulcer.

  • Culture of discharge. A culture may be submitted if a secondary bacterial infection is suspected.

  • Viral assays. Scrapings of the conjunctiva may be taken to submit to special laboratories to try and identify the presence of feline herpesvirus. Confirming an active infection of this virus can be difficult. The virus has the ability to become latent or quiet, leading to negative test results.

  • Routine blood work. Your veterinarian may recommend blood tests including a complete blood count and serum biochemistry profile if an underlying disease is suspected.

    Treatment In-depth

    Treatment is aimed at increasing tear production, applying artificial tears, and reducing any bacterial infections or inflammation .

  • When using eye medications, be sure to ask your veterinarian whether the medications can be administered at the same time, or whether they should be separated by several minutes. Some medications can be administered together; others need to be administered alone. In general, drops are applied prior to ointments, and no more than two medications are given together at one time.

  • Application of 0.2% cyclosporine ointment can be tried in the cat to increase tear production. Cats do not always tolerate topical cyclosporine, and the ointment is not always commercially available. When the cat does tolerate it and tear production does improve with the drug, it must be used on a long-term basis.

  • Oral pilocarpine drops have been tried in the past to increase tear production, but they are not usually recommended in the cat because they do not work well and commonly produce side effects (salivation, vomiting, diarrhea).

  • In most cats with KCS, artificial teardrops and ointments are the primary agents used to combat their dry eye. This is particularly true in cats that do not tolerate or do not respond tocyclosporine. Drops provide moisture and ointment provides lubrication to the surface of the eye.

  • Antibiotic drops or ointment may be used if a secondary bacterial infection or a corneal ulcer is present.

  • Corticosteroid drops or ointment may be used to decrease inflammation. These medications are only used after fluorescein staining of the cornea has determined that there is no ulceration present. Corticosteroids cannot be used in the presence of a corneal ulcer because they delay healing.

  • Occasionally topical anti-viral medications may be tried for herpesvirus. These medications are expensive, must be applied frequently throughout the day, and it is not known how beneficial they are in the treatment of KCS in the cat.

  • In severe cases of KCS that do not respond to medications, surgery may be performed in which the opening of a salivary duct is moved from the mouth to the eye. This results in saliva flowing over the eye to keep the eye moist. It is not an ideal treatment for KCS because saliva is not the same as tears, and the flow of saliva cannot be controlled very well. The surgery is helpful, however, for those cats that remain persistently painful and squinty despite trying all forms of medical therapy.

  • It is important that treatments are done on a consistent basis. Most cats with KCS cannot be cured, but the disease can be controlled with medications. Diligent care is often necessary long term to keep the cat comfortable.

    Care at home also consists of keeping the eye lubricated and clean.

  • If the cat tolerates it, you can use an irrigating eye solution to rinse the eye to remove the discharge that is present. The irrigating eye solution can be obtained without a prescription at any drug store. Gently rinse the eye and remove the discharge using a tissue. If the cat does not tolerate the eyewash, then remove the discharge with a warm, wet cloth. Always remove excessive discharge from the eye prior to application of medication.

  • Return for regular follow-up visits to re-evaluate the tear production.

  • Monitor the eye for changes. If the discharge or redness gets worse despite treatment, have your cat re-evaluated by your veterinarian as soon as possible.

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