Corneal topographic changes after refitting polymethylmethacrylate contact lens wearers into rigid gas permeable materials.

Polymethylmethacrylate (PMMA) contact lenses can alter corneal shape and induce corneal warpage or distortion. The purpose of our study was to determine the effects on the corneal topography after immediate refitting of long-term PMMA contact lens wearers into rigid gas permeable (RGP) materials. Six eyes with contact lens induced corneal warpage from PMMA contact lenses were assessed using the Topographical Mapping System-1. Statistical analysis was performed for the following variables prior to and approximately 6 months after contact lens refitting: best spectacle visual acuity, manifest refraction, surface regularity index, surface asymmetry index, keratometry, and simulated keratometry. Best spectacle visual acuity improved an average of 1.8 +/- 1.0 (mean +/- SD, P < 0.05) lines of Snellen visual acuity, while refraction did not change appreciably. The surface regularity index diminished by 0.51 +/- 0.32 (P = 0.01). The surface asymmetry index improved by 0.32 +/- 0.26 (P < 0.05). There was a good correlation between keratometry and simulated keratometry, and neither changed significantly after refitting with RGP contact lenses. All general topographic patterns remained unchanged throughout the study. Immediate refitting of long-term PMMA contact lens wearers into RGP materials of similar fit allows a slightly more regular and symmetric central corneal shape, which can result in improved spectacle visual acuity. The general corneal topographic patterns of contact lens induced corneal warpage did not change or improve after refitting to RGP material.