Corneal swelling responses with extended wear in naive and adapted subjects with menicon RGP contact lenses

Overnight corneal swelling responses to Menicon SF-P and EX rigid gas permeable (RGP) contact lenses were determined in 20 human volunteers previously adapted to lens wear and in five volunteers who had no prior contact lens experience. Slit lamp biomicroscopy revealed no evidence of lens adherence in either group. Overnight wear of both lenses produced greater corneal swelling in naive (8.732% +/- 1.50%) than in adapted eyes (5.016% +/- 1.10%) (P less than .00005). These results suggest that, at least for the lenses tested, adaptation to contact lens wear may down-regulate overnight swelling responses to levels at or near no lens wear or daily-wear values for the same lenses. Both the EX and SF-P lenses appear to satisfy Holden's criteria for zero residual swelling, suggesting promise for successful clinical extended wear.