Predictive factors associated with axial length growth and myopia progression in orthokeratology

Purpose To investigate the factors affecting axial length (AXL) growth and myopia progression in orthokeratology. Methods This prospective, observational study enrolled 28 new orthokeratology lens wearers from a contact lens clinic between March 2016 and March 2017. Among them, 32 eyes of 17 wearers who completed one year of follow-up were finally analyzed. All participants underwent central (C) and peripheral (nasal 30 degrees [N30] and temporal 30 degrees [T30]) AXL measurements as well as central and peripheral refraction, ocular aberrations, and corneal topography at baseline and every posttreatment visit. A generalized estimating equation (GEE) was used to assess the associations between AXL change and all independent variables in both eyes. Results The mean central AXL was 24.21 +/- 0.60 mm and the mean baseline central spherical equivalent refractive error (SER) was -2.43 +/- 0.97 diopters (D). Among all parameters that were significantly associated with AXL change in univariable GEE analyses, the baseline difference in AXL between C and N30 (beta = -0.213, p < 0.001), baseline SER (beta = -0.040, p < 0.033), posttreatment coma (beta = -0.291, p < 0.031), third-order higher-order aberrations (HOAs) (beta = -0.482, p < 0.001), and changes in second-order aberrations (beta = 0.025, p = 0.027) at one year of follow-up were identified as significant factors in multivariable GEE analysis. Conclusions The inhibition of AXL elongation and myopia progression in orthokeratology lens wear is significantly associated with the peripheral myopization and asymmetric optical changes mostly induced by third-order HOAs.