Evaporation rate of water from the precorneal tear film and cornea in the rabbit

¹ Department of Cornea Research, Retina Foundation, Institute of Biological and Medical Sciences Boston, Mass

A technique for the study of evaporation from the precorneal and corneal surfaces has been developed. Evaporation from the superficial lipid layer (SLL) has been measured to be 10.1 x 10^-7 Gm.cm.^-2sec^-1 When this lipid layer is removed, evaporation increases around fourfold. Evaporation from the dry epithelial surface occurs at a rate of 1.8 x 10^-7 Gm.cm.^-2sec^-1 After the epithelium is removed, a twentyfold increase in evaporation rate occurs. The specific resistances (u) to evaporation of these layers have been calculated: epithelium, = 82.5 sec./cm.; SLL,= 12.9 sec/cm.; aqueous tears, 1 sec/cm.; stroma, 0 sec./cm. Thus, the superficial lipid layer is effective in retarding evaporation of the precorneal tear film. Its effectiveness compares favorably to that of condensed monolayers of long-chain fatty alcohols on pure water, known to be efficient in retarding evaporation. The epithelium functions as a barrier to water flow and is highly effective in retarding evaporation in the absence of a tear film.

Key Words: Corneal evaporation • tears • lipids • corneal epithelium • corneal stroma • corneal measurements • time factors • mathematical analysis • rabbits

Submitted on February 4, 1969
Accepted on May 5, 1969

This article has been cited by other articles:

				M. H. Levin and A. S. Verkman Aquaporin-Dependent Water Permeation at the Mouse Ocular Surface: In Vivo Microfluorimetric Measurements in Cornea and Conjunctiva Invest. Ophthalmol. Vis. Sci., December 1, 2004; 45(12): 4423 - 4432. [Abstract] [Full Text] [PDF]