Keratoconjunctivitis sicca (KCS) or “Dry Eye”
What is KCS?
Keratoconjunctivitis sicca is a disease characterized by inflammation of the cornea and conjunctiva (pink tissue covering the whites of the eyes and the inside of the eyelids) secondary to inadequate tear production by the tear glands. When an inadequate level of tears is present, debris and bacteria (that are normally washed away by the tears) build up and a thick mucous discharge forms. The disease is usually caused by inflammation of the lacrimal glands, but can also be caused by the toxic effect of certain drugs on the lacrimal glands or by lack of nerve innervation to the lacrimal glands.
How do I know if my pet has KCS?
Redness, squinting or blinking, and discharge are early signs of disease and indicate irritation and discomfort. Chronic cases will develop pigmentation and scarring of the cornea. The most common sign is a thick yellow-green ocular discharge. Normal tears are necessary to provide nutrition and oxygen to the cornea as well as prevent bacterial overgrowth. Redness, cloudiness, and squinting are signs of irritation due to inadequate tears. Thick discharge develops when the tears are not present to wash away bacteria and debris on the surface of the eye.
How is KCS treated?
Treatment is aimed at promoting your pet’s tear production, reducing inflammation, and supplementing the inadequate tears. Lacrimostimulants are medications that stimulate tear production by the tear glands and decrease inflammation, including cyclosporine and tacrolimus. These medications can take 4-6 weeks before a maximal response is seen, and it is important to supplement the tears at least until that time. Artificial tears work for 30 minutes or so and can be used to supplement tear stimulants.
Parotid duct transposition is a surgical option that can be considered in cases that are non-responsive to medications.
Prognosis depends on your pet’s response to therapy. About 80% of patients with KCS respond favorably to topical lacrimostimulants. Most pets begin to feel better within several days of initiating therapy. Dogs with allergies, poor eyelid conformation, a pronounced globe, or ear disease tend to have more difficult disease.
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