Patients in the study will undergo a complete eye examination, and a small tear sample will be collected to study tear consistency and composition. A small amount of conjunctiva (the clear, thin covering of the eye lining the eyelids and eyeball) will be removed to study substances in it that might provide information on what causes dry eye. A blood sample also will be taken to look for antibodies found in patients with Sjogren's syndrome, a disorder characterized by dryness of the mouth, eyes and other mucous membranes. Patients will also fill out forms providing information on the extent to which their dry eyes bother them.