Corneal response to short-term orthokeratology lens wear

Purpose. This study investigated short-term corneal changes induced by reverse-geometry lenses worn for orthokeratology. Methods. Nine young adult subjects wore reverse-geometry rigid gas-permeable lenses (BE; UltraVision Contact Lenses, Brisbane, Australia) in one eye only for 10, 30, and 60 min in the open eye and 8 h in the closed eye. The fellow eye acted as a non-lens-wearing control. Corneal topographic changes were monitored using the Medmont E-300 corneal topographer and keratometry. Changes in uncorrected logarithm of the minimum angle of resolution (log MAR) visual acuity were also recorded. Data were analyzed by analysis of variance and post hoc t-tests. Results. Significant central corneal flattening (-0.61 +/- 0.35 D; p = 0.014) and the formation of a defined "treatment zone" (diameter, 3.86 +/- 0.88 mm) were found after 10 min of open-eye lens wear, which progressed with increasing periods of lens wear. Significant improvement in unaided logMAR (-0.16 +/- 0.18; p = 0.005) was also apparent after 10 min and showed further improvement with longer periods of lens wear. Corneal asphericity showed a trend toward corneal sphericalization, which reached statistical significance after 8 h of lens wear. There was no significant change in corneal toricity. Conclusions. The cornea responds rapidly to the application of reverse-geometry lenses for orthokeratology, with significant central corneal flattening and improvement in visual acuity after just 10 min of lens wear. This suggests that the corneal epithelium is able to be molded or redistributed very rapidly in response to the tear film forces generated behind reverse-geometry lenses.