Influence of Ocular Wavefront Aberrations on Axial Length Elongation in Myopic Children Treated with Overnight Orthokeratology

Purpose: To determine ocular optical parameters that affect axial length elongation in myopic children undergoing overnight orthokeratology. Design: Prospective, noncomparative study. Participants: Fifty-nine subjects who met the inclusion criteria were enrolled in this study. Methods: Axial length and ocular wavefront aberration were assessed before and 1 year after the start of orthokeratology. Corneal topography was performed, and then corneal multifocality was calculated for a 4-mm pupil. After evaluating simple correlations between axial elongation and optical parameters, multiple linear regression analysis was performed to identify explanatory variables with a statistically significant contribution to axial elongation. Main Outcome Measures: Axial length and ocular wavefront aberration before and 1 year after the start of orthokeratology. Results: Fifty-five subjects completed the 1-year follow-up examinations. At baseline, their age ranged from 7.2 to 12.0 years. The manifest spherical equivalent refractive error ranged from -3.50 to -0.75 diopters. The mean axial length significantly increased from 24.20 mm at baseline to 24.43 mm 1 year after treatment. The axial elongation showed significant simple correlations with the change in C-2(0), change in second-order aberration, change in coma-like aberration, change in spherical-like aberration, change in total higher-order aberrations, change in corneal multifocality, baseline age, and baseline spherical equivalent refractive error, but not C-4(0). Multiple linear regression analysis showed that the change in coma-like aberration was the most relevant variable. Conclusions: Asymmetric corneal shapes, rather than concentric and radially symmetric shapes, have a considerable effect on retardation of axial elongation, suggesting that the inhibitory effect of orthokeratology on myopia progression is caused by mechanisms other than the reduction in peripheral hyperopic defocus. (C) 2015 by the American Academy of Ophthalmology.