Human corneal oxygen demand: the closed-eye interval.

A micropolarographic system was used to measure the flux of oxygen crossing the tear epithelial interface of the human cornea just following lid-closure periods of 0-15 min, and just following a series of brief lid openings (0.2-0.3 s) of frequencies from 0 to 30 times/min. In all, 462 measurements spanning those two formats were made on the corneas of seven young healthy subjects. In the extended-closure format the average rate increased over the first 5 min, then stabilized at 2.51 times the oxygen-uptake rate under normal open-eye conditions. In the brief lid-opening format, frequencies of 30 openings/min reduced the oxygen uptake rate to 70% of that of the stabilized closed eye. Individual differences noted among subjects may influence their relative success in extended contact lens wear, and natural lid and eye movements during sleep may have at least transient effects on corneal oxygen supply and demand during those periods.