The VITamin D and OmegA-3 Trial (VITAL; NCT 01169259) is a randomized clinical trial in 25,875 U.S. men and women investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor fish oil, 1 gram) reduces the risk of developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This ancillary study is being conducted among participants in VITAL and will examine whether omega-3 fatty acids or vitamin D3, compared to placebo, reduce the incidence and/or progression of dry eye disease.

This ancillary study to VITAL will examine the efficacy of omega-3 fatty acids and vitamin D3 in prevention of dry eye disease. The primary aims are to test whether omega-3 fatty acid supplementation (1) reduces the incidence of dry eye disease, and (2) improves the natural history of dry eye disease by relieving symptoms and other impacts on quality of life. Secondary aims are to estimate the incidence of dry eye disease in the US, prospectively examine the natural history of dry disease, explore factors that could modify or influence the impact of omega-3 fatty acid supplementation, evaluate the interrelationship of dry eye disease and depression, and test for possible independent or joint effects of vitamin D3 supplementation in the incidence and natural history of dry eye disease.

Inclusion Criteria:

• All participants in VITAL (NCT 01169259) are eligible to participate in this ancillary study.

Exclusion Criteria:

• None