Abstract

Apart from its optical duties as the initial refracting surface of the eye, the preocular tear film serves as a major protective environment for the cornea. The tear layer provides a depot of dissolved oxygen and other metabolites, affords a pathway for "used" metabolic products to escape the cornea, and, with its complement of biochemical agents, acts as a formidable defense against invading micro-organisms. To facilitate these functions, it is imperative that the surface of the eye be kept moist, and the extreme discomfort accompanying even short periods of surface dryness provides evidence of the importance of maintaining this thin layer of fluid on a continuous basis.

© 1996 Optical Society of America