Dry eye is a condition where there is a deficiency in the water portion of tear film leaving oil and mucus. This lack of essential tear production is what causes irritation. To diagnose dry eye we perform a test called the Schirmer Tear Test that indicates the quantity of tears are being produced by each eye. To treat dry eye we use a topical form of cyclosporine. The reason we use an immunosuppressant drug is to suppress the immune destruction of the tear duct that adds to dry eye symptoms. Majority of the time medication is needed long term.