A Pilot Study on Corneal Molding Speed as a Function of Oxygen Permeability of Lens Materials in Orthokeratology

OBJECTIVE : This study was conducted to evaluate the impact of varying lens oxygen transmis-sibility (DK) on corneal molding speed, after short-term orthokeratology (OK) lens wear. METHODS: This is a pilot prospective randomised study. Participants (aged 8–15) were seen during four visits over 3 days and were fitted with lens 1 (DK100) or lens 2 (DK180), randomly assigned. From topographic tangential differential maps, treatment zone diameter (TZD), mid-peripheral power (MPP) and width (MPW) were extracted. The total high-order aberrations (HOAs), spherical aberrations and coma were measured (5 mm diameter). RESULTS: Twelve participants were enrolled (-4.35 ± 0.89D OD; -4.18 ± 0.88 OS). At day 1, L1 corrected 60% of the refractive error, and 73% by day 3 (p=0.003), compared to 73%/97% with L2 (p=0.021). The HOAs increased significantly with both lenses after 1 and 3 days (p=0.003; p=0.036). The TZD reached 25% of the pupil area with no significant difference between the two lenses at day 1(p=0.869) or 3 (p=0.429). The MPW did not vary significantly between lenses with time. However MPP was sa-tistically significant with L2 at Day 3. (p=0.020).CONCLUSION: Using a higher DK material re-sulted in faster refractive error correction and higher mid-peripheral power generated during the first 3 days of OK lens wear.