Objective Evaluation of Ocular Surface Lubricants

This study will objectively evaluate ocular surface lubricants in subjects with dry eye syndrome. Lubricants contain compounds that are purported to improve dry eye symptoms, although objective data is not available. The investigators seek to objectively evaluate the effectiveness of two lubricants and compare the results to a saline eye drop (control). The investigators will assess the lipid layer before and after the administration of three products in the same eye of 25 dry eye subjects using the ellipsometry, imaging in a "normal" environment. Subsequently the investigators will change the environment to one that causes the subjects' ocular surface to experience "evaporative stress" (warmer, less humid and greater air flow) and perform the before and after drop administration measurements with the same three products in the same eye as the first environment.