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T. Hiraoka, Y. Matsumoto, F. Okamoto, T. Yamaguchi, Y. Hirohara, T. Mihashi, T. Oshika; Corneal higher–order aberrations induced by overnight orthokeratology . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1548.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Orthokeratology is defined as the temporary reduction of myopia by the application of specifically designed rigid contact lenses. The temporary reduction in myopia and improvement of unaided vision were achieved by flattening the corneal curvature with a flat–fitting rigid contact lens. However, modification of the corneal shape to correct myopia can cause undesirable side effect on visual performance. We evaluated corneal higher–order aberration induced by overnight orthokeratology for myopia. Methods: Sixty–four eyes of 39 patients undergoing overnight orthokeratology for myopia were examined. Inclusion criteria were uncorrected visual acuity of 20/20 or better after treatment and minimum follow–up of 3 months. Mean age was 15.6 ± 6.2 years (range 11 to 37). Mean spherical equivalent before treatment was –2.60 ± 1.13 D (range –0.75 to –5.25). Videokeratography data were obtained with computerized videokeratography (TMS–2N, Tomey). Higher–order aberrations of the cornea were calculated from the height data for 3–, 4–, and 6–mm pupils. Results: By orthokeratology, come–like aberration (3rd order RMS) significantly increased for 3–mm (P<0.0001, paired t–test), 4–mm (P<0.0001), and 6–mm (P<0.0001) pupils. Similarly, spherical–like aberration (4th order RMS) increased significantly by the treatment for 3–mm (P=0.0001), 4–mm (P<0.0001), and 6–mm (P<0.0001) pupils. Increases in the coma–like and spherical–like aberrations showed significant positive correlations with the amount of myopic correction for 3–mm (Pearson correlation coefficient, R=0.452, P=0.0001 for coma–like aberration, R=0.381, P=0.0017 for spherical–like aberration), 4–mm (R=0.478, P<0.0001, R=0.484, P<0.0001), and 6–mm (R=0.499, P<0.0001, R=0.455, P=0.0001) pupils. Conclusions: Corneal higher–order aberrations significantly increased even in clinically successful orthokeratology cases. The increases in the higher–order aberrations correlated with the magnitude of myopic correction. Although the influence of these changes on visual function should be further studied, correction of high myopia by orthokeratology might affect visual performance.
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