Effect of fenestration soft contact lenses on corneal oxygen availability.

Recent clinical and experimental evidence suggests that a better physiological response to hydrogel lens wear can be obtained with fenestrations. To determine whether those observations could be attributed to increased corneal oxygenation, the equivalent oxygen percentage (EOP) was measured at the cornea of eight subjects wearing hydrogel contact lenses which had multiple fenestrations of 0.8 and 1.8 mm. It was possible to increase the mean EOP by 1.7 +/- 1.3% O2 (p less than 0.002) beneath a standard thickness lens using four 1.8-mm fenestrations. However, such lenses were uncomfortable to wear. Fenestrations that provided comfortable wear (0.8-mm diameter) did not significantly increase the EOP beneath standard thickness lenses (-0.1 +/- 1.0% O2, p greater than 0.1 for four fenestrations, and +0.2 +/- 1.2% O2, p greater than 0.1 for eight fenestrations) or ultrathin lenses (-0.1 +/- 1.3% O2 p greater than 0.1 for four fenestrations). It is concluded that fenestrations do not provide a clinically efficient means of increasing the oxygen tension beneath hydrogel contact lenses.