Keratoconjunctivitis sicca, or KCS, (commonly known as Dry Eye) is a fancy way of saying the eye is dry. Kerato refers to the cornea or clear covering of the eye that faces the outside world. Conjunctivae are the moist pink membranes of the eye socket. "It is" means inflammation and sicca means dry. KCS means inflamed, dry cornea and conjunctiva. It occurs when there is a deficiency in the water portion of the tear film that normally accounts for 95% of the tear volume. Without the water, one is left with oil and mucus; hence, the gooey yellow eye discharge characteristic of this condition.
Tears are essential to the comfort of our eyes but they do more than just provide lubrication. Tears contain anti-bacterial proteins, salts, sugars, and even oxygen to nourish the eye. Tears flush away irritants and infectious agents that are constantly getting in our eyes. Since the outer portions of the eye does not have a blood supply, the tears must bring sugars and oxygen and must remove metabolic waste.
There are many causes of dry eye. The most common cause of KCS appears to be immune mediated destruction of the tear-producing gland tissue.Distemper infection attacks all body interfaces with the environment including the eyes. Dry eye is part of the constellation of symptoms that can occur with distemper infection.
There could be a congenital lack of tear producing gland tissue (as described in certain lines of Yorkshire terrier). Exposure to sulfa containing antibiotics (such as Trimethoprim sulfa combinations) can lead to dry eye (which can be either temporary or permanent and occurs unpredictably).
Anesthesia will reduce tear function temporarily (thus eyes are lubricated with ointment by the attending nurse.) A knock on the head in the area of one of the tear producing glands can lead to KCS.
Artificial tears can be purchased in most drug stores. These can be combined with other therapies and are certainly very soothing. The problem is that they are typically recommended for use 4 to 6 times a day.
Antibiotic products are often needed especially when starting treatment for KCS as secondary infections are common when there are inadequate tears to wash infectious agents away. These products do not increase tear production but may be important, especially early in therapy.
Mucomyst® Eye Drops are made from a respiratory product used to dissolve thick mucus. In an eye formula, Mucomyst (active ingredient is Acetylcysteine) helps remove the thick eye discharge that accompanies dry eye.
