Corneal oxygen demands: a comparison of the open- and closed-eye environments.

Equivalent oxygen (E.O.P.) responses, using a mammalian corneal model, were measured for open- and closed-eye conditions, and with and without the presence of a silicone, a standard thickness HEMA, and an ultrathin HEMA contact lens. Under open-eye conditions, the silicone lens even with a center thickness of 0.25 mm, diminished the E.O.P. response insignificantly compared to the no-lens condition. The ultrathin HEMA lens (0.06-mm center thickness) produced a response approximately three times superior to that of the standard thickness HEMA lens. Under closed-eye conditions, only the silicone lens, however, caused the cornea to respond within the Polse-Mandell zone.