Corneal edema with several hard corneal contact lenses.

Five patients were each fitted with polymethylacrylate (PMMA), BP Flex, and Polycon corneal contact lenses of the same dimensions. Corneal edema was monitored with a slit-lamp biomicroscope and pachometer. Lenses were worn in a double-masked and random sequence for periods of 6 hr. Patients developed less corneal edema with Polycon lenses than with PMMA lenses. There was no significant difference in corneal edema with PMMA and BP Flex lenses. Those patients who developed little corneal edema with optimum-fitting PMMA lenses also developed little edema with the BP Flex and Polycon lenses. Steeper-fitting PMMA and BP Flex lenses produced more corneal edema than optimum-fitting lenses made of the same materials, while steeper-fitting Polycon lenses produced only slightly more edema than the optimum-fitting Polycon lenses.