Oxygen flux into the aberrant cornea

Polarographic oxygen sensors placed on the postsurgical human cornea indicate subnormal oxygen uptake rates. Given the nature of the method of measurement (due to Hill and Fatt), this implies that epithelial oxygen consumption rate is reduced post-surgically. However, other studies using the Rasson-Fatt method report no difference in corneal oxygen uptake through a thick soft contact lens after unilateral surgery. Application of a recently described three-layer computer model of corneal oxygen distribution suggests that the difference between normal and postsurgical corneal oxygen flux is greater at high precorneal oxygen tensions (the measurement area of the Hill-Fatt method). In contrast, the difference is small at low precorneal oxygen tensions, which would tend to confound efforts to detect a difference in postsurgical corneal oxygen uptake using the Rasson-Fatt method. This probably explains the null results reported previously.