Differential Diagnosis of Sjögren's Versus Non-Sjögren's Dry Eye

Inclusion Criteria: * Capacity to give informed consent * Self-reported literacy * Best corrected visual acuity at distance 20/40 in each eye * Signed Institutional Review Board (IRB) approved consent agreeing to terms of the study * Additional inclusion criteria for the dry eye group (both SS- and non-SS) will include a previous diagnosis of dry eye made by an eye care specialist. * Differentiation of SS-related versus non-SS dry eye will be made according to the 2016 revised SS classification criteria. The classification criteria are based on the weighted sum of the below 5 items: • SS laboratory findings * Anti-Sjogren's Antibody A (SSA) antibody positivity * Focal lymphocytic sialadenitis with a focus score ≥ 1 foci/mm2 each scoring=3 • SS clinical findings * Abnormal ocular staining score ≥ 5 (or van Bijsterveld score ≥ 4) in one eye * Schirmer test ≤ 5 mm/5 min (without anesthesia) in one eye * Unstimulated salivary flow rate ≤ 0.1 mL/min each scoring=1 Individuals who have a total score ≥ 4 for the items above, meet the criteria for primary SS. In other words, for final classification, an individual should have at least one laboratory and one clinical finding. Additional inclusion criteria for control subjects will include no previous history of dry eye diagnosis, and no known history of autoimmune disease, verified using a review of systems and past medical history form. Exclusion Criteria: * Age less than 18 years * Known diagnoses of: Hepatitis C in…