Comparison of clinical diagnostic tests in hydrogel extended wear

We compared the relative value of biomicroscopy, pachometry, esthesiometry, and corneal oxygen flux measurements for the detection of corneal hypoxia in myopic patients wearing hydrogel extended wear lenses. Measurements were standardized by relating the change in each parameter to its test-retest reliability. After 3 months of extended wear the greatest change occurred in biomicroscopic signs (microcysts and vacuoles, fluorescein staining, inferior conjunctival hyperemia) and in stromal edema measured with pachometry. These four signs were poorly correlated to each other (Pearson's r < 0.3), indicating that none could be considered redundant. Stromal striae, endothelial edema (blebs), esthesiometry, and corneal oxygen flux measurements showed relatively little change during the period of lens wear.