Dry eye disease or keratoconjunctivitis sicca is acommon and often under diagnosed condition that affects> 10% of the adult population. This condition has beenclassified into two separate, but overlapping, categories –tear deficiency and evaporative loss. Diagnosis isconfused by the lack of a single diagnostic test. Newconcepts of pathogenesis have shown that dry eyedisease appears to be caused by inflammation mediatedby T-cell lymphocytes. 0.05% Cyclosporine A ophthalmicemulsion offers the first therapeutic treatment for patientswith moderate-to-severe dry eye disease due to teardeficiency.