Refractive Index and Reflectance of the Anterior Surface of the Cornea

A new type of probe devised for the Goldmann applanation tonometer depends for its operation on the difference in critical angles for glass‐tear fluid and glass‐cornea interfaces. The probe failed to work correctly, and subsequent investigations to determine why were directed at the physical structure of the pre‐corneal tear film. Photometry indicated that the anterior surface of the cornea in vivo reflected up to 8% of the incident light. more than seems generally supposed. Calculations of the anterior corneal surface reflectance indicate that two‐or three‐layer models of the pre‐corneal film fit the observations. Slit‐lamp observations indicated that the reflectance of the corneal epithelium is much lower than that of the endothelium.