Patients with uveitis that is 1) known to be due to sarcoidosis; 2) suspected to be due to sarcoidosis based on specific diagnostic criteria; and 3) known not to be due to sarcoidosis may be enrolled in this study. Participants will undergo an eye examination, blood tests, chest X-ray, and skin test for tuberculosis and other infections. Small tissue samples from the conjunctiva (the thin lining covering the outside of the eye and the inside of the eyelid) and the lacrimal (tear) gland will be taken after the eye is numbed with anesthetic drops and injection.