Reliability of corneal oxygen flux measurements

Serial oxygen flux measurements were obtained from the same cornea of 5 human subjects after exposure to ambient air, a test gas mixture (2% oxygen, balance nitrogen) and 100% nitrogen at 2 individual measurement sessions. Analysis of variance (ANOVA) of the individual flux measurements for the test gas indicates that there were significant differences in corneal oxygen flux rates among subjects and sessions. Referencing the flux data for the test gas to the data for ambient air reduced the variability of data between sessions, although significant intersubject differences were still present. By referencing the flux data for the test gas to the concurrent air and nitrogen data, differences among subjects, as well as sessions, were reduced to the extent that they were not statistically significant. Standardization of data is important in the interpretation of corneal oxygen flux data so that intersubject and intersession differences can be minimized.