KCS, or dry eye, is the result of inadequate tear production. Tears function as a nutritive, immunoprotectant, lubricant and cleansing layer for the cornea and conjunctiva. Because the cornea does not have blood vessels, tears perform the same functions that blood does to other tissues. Without the protection of adequate tears, the eye becomes painful and severe, degenerative corneal changes begin to take place. Chronic patients can easily become blind due to heavy corneal pigmentation.

Common symptoms are a dull cornea, inflamed sclera and thick, sticky discharge. The actual diagnosis is made by doing a Schirmer tear test (STT) to measure tear production.

Treatment involves lubricants, antibiotics and cyclosporin, an immunosuppressant drug that can increase tear production.