Tear Film Interferometry as a Diagnostic Tool for Evaluating Normal and Dry-Eye Tear Film

Abstract

The technique and method of thin film interferometry is being increasingly employed in the examination of the lipid layer of the in vivo tear film in normal and dry-eye individuals, with and without contact lenses present.^1–10 This technique permits determination of the thickness of the superficial lipid layer that floats upon the normal tear film and of the fluid layer that covers the anterior surface of contact lenses. In general, these thickness estimates have been based upon the general hue (color) of the reflected interference patterns. For reasons discussed later, the determination of overall tear film thickness (i.e., from air boundary to corneal surface) is not easily accomplished, as can be verified by the work of Prydal et al.^11,12