Changes in oxygen transmission (Dk/L) of extended wear flexible contact lenses over time as a result of patient wear

Thirty-nine subjects (78 eyes) were fitted on a contralateral basis with extended wear flexible contact lenses of three different water contents (38.5%, 55.0%, and 74.0%). A regimen of care (solutions without preservatives) and wear (conservative - only seven days continuous) was extremely well-tolerated by the population sample. Oxygen transmissibility (Dk/L) measurements were made with a polarographic cell and oxygen permeometer apparatus over a 150 day wearing period on the originally dispensed and replacement contact lenses. Analysis of the lens data from subjects who completed the whole period of study demonstrated no statistically significant change in the oxygen transmissibility values. However, after the first three weeks of wear, an actual increase in the Dk/L values was observed for all lens types. This finding may have potential clinical significance. Repeatability tests performed throughout the period of this project c onfirmed the validity and reliability of the polarographic cell and oxygen permeometer method for assessing corneal oxygen availability