Oxygen tension beneath contact lenses under the closed eyelid: human eye measurements.

An equivalent oxygen technique was used to measure the level of oxygen beneath one daily wear lens (HEMA) and two extended wear lenses (Permalens and Gelflex 75) under the closed lid of the in vivo human eye. The cornea responded as if it was in an anoxic environment with the HEMA lens, whereas the extended wear lenses resulted in responses just beneath the level of the Mandell-Farrell limit. These findings are compared with model predictions, and their physiological consequences are discussed.