Changes in corneal radius and thickness in response to extended wear of rigid gas permeable contact lenses.

Abstract

PURPOSE: In this study we assessed patients' clinical tolerance to extended wear of Hoya Hard EX contact lenses, which have a Dk of 125, and determined resulting changes in corneal radius and thickness. METHODS: Hoya Hard EX rigid gas permeable contact lenses (Dk = 125) were fitted to 57 eyes of 29 patients; all eyes were free of pathology. The average duration of contact lens wear was 5.28 +/- 1.43 days. Changes in the radius and thickness of the cornea were measured after 1,3, and 6 months of lens wear. RESULTS: At 1 month, keratometer readings indicated significant flattening in both the horizontal (P < 0.01) and vertical meridians (P < 0.001). At 3 and 6 months, the flattening of both meridians had become more significant (P < 0.001). Although there were no statistically significant changes in corneal thickness at 1 month, significant decreases in thickness were observed at 3 and 6 months (P < 0.001). During the study, patients' vision was stable and lens wear caused no serious complications. At the end of the study, all 29 patients continued extended wear of their contact lenses. CONCLUSIONS: High-Dk RGP contact lenses are an alternative to soft lenses for extended wear.