Subfoveal choroidal thickness and axial length changes with orthokeratology in bilateral anisomyopia

Purpose To investigate the change in subfoveal choroidal thickness (SFChT) in bilateral anisomyopic children undergoing orthokeratology (ortho-k) over 2 years and the association with axial elongation (AE). Methods SFChT, axial length and refractive data from 26 bilateral anisomyopic subjects (aged 7-12 years) who participated in a 2-year prospective orthokeratology study were analysed using generalised estimating equations and linear mixed models. Results SFChT in the more myopic eyes (MME) (at least 1.50 D more myopia than the fellow eye) became thicker (mean +/- standard deviation change, 25 +/- 20 mu m) after 6 months of ortho-k lens wear (p < 0.001) and remained stable thereafter (p >= 0.13), but no such change was observed in the less myopic eyes (LME) (p >= 0.07). Combining data from both eyes, the baseline SFChT and SFChT change after 2 years of ortho-k treatment were associated with 2-year AE [generalised estimating equation (accounting for the inclusion of both eyes): beta = 0.002, p = 0.03 and beta = -0.005, p < 0.001, respectively]. Conclusions After 2 years of ortho-k treatment, the increase in the SFChT occurred exclusively in the MME. Considering both eyes, greater SFChT thickening was associated with less eye growth.