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Thesis

A clinical investigation between two different rigid gas permeable contact lens materials based on oxygen permeability (Dk)

1 May 1989

Abstract

The varying oxygen permeability of rigid gas permeable materials continues to be a primary concern among contact lens manufacturers. Manufacturers promote that more oxygen permeability leads to greater comfort, and less corneal edema. In this study, Paraperm EW, a moderatly high Dk lens, and Polycon II, a relatively low Dk lens were clinically evaluated for patient comfort, corneal edema, related changes in corneal curvature, and any refractive changes. Both objective clinical data and subjective patient responses were used to determine whether the current low Dk lenses are as effective as the higher Dk lenses for daily wear. Fourteen subjects were fit with a pair of Paraperm EW lenses and a pair of · Polycon II lenses, of which ten subjects completed the study. One lens from each pair was worn on each eye. Following a period of two months the lens types were reversed so that each eye had worn each type of lens for two months. No significant difference was seen between either of the lens materials with respect to objective clinical data and subjective preference. The results, therefore, indicate very little difference between the low Dk material and the higher Dk materials with respect to corneal thickness changes, corneal curvature or refractive changes, or patient preferences over the four months of the study.


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