Correlation between retinal defocus distribution and axial growth in myopic children wearing orthokeratology lenses

The purpose was to investigate the refractive status of different retinal regions in myopic children treated by orthokeratology (ortho-k) and its relationship with axial elongation. This was a cross-sectional study. Axial length measurements were retrospectively collected from 221 myopic children aged 9–15 years who underwent ortho-k lens wear for over 1 year. The relative peripheral refractive errors (RPREs) of different retinal zones were measured using multispectral refraction topography, and the distribution characteristics were analyzed. All subjects were divided into the fast progression (axial growth > 0.15 mm/y) and slow progression (axial growth ≤ 0.15 mm/y) groups. The linear and logistic regression were performed to evaluate the correlation between axial growth and retinal defocus. Receiver operating characteristic (ROC) curve analysis determined the diagnostic efficiency of regional retinal defocus in the two groups. After ortho-k lens wear, the myopic defocus was located in the circular regions of 0–15˚ and 15–30˚ of the retina and the superior-inferior quadrants. While hyperopic defocus predominated in other zones, the superior-inferior and nasal-temporal quadrants showed an asymmetric defocus distribution in the slow progression group (P < 0.001). The multivariate linear regression demonstrated that the annual axial growth was positively correlated with the superior retinal RPRE (standardized beta = 0.313, P < 0.001) but negatively correlated with age (standardized beta=-0.181, P = 0.005). The logistic regression analysis revealed that the smaller superior RPRE (odds ratio OR = 2.731; 95% confidence interval CI, 1.298–5.747; P = 0.008) and older age (OR = 0.856; 95%CI, 0.740–0.990; P = 0.036) were protective factors against rapid axial growth. The superior REPE exhibited an area under the ROC curve of 0.619, indicating its limited efficiency in predicting axial growth. After ortho-k lens wear, myopic defocus and hyperopic defocus were located in different zones of the retina. The smaller superior retinal RPRE and older age are protective factors but poor standalone predictors for axial growth.