Weighted Zernike defocus coefficient of treatment zone is a meaningful indicator for myopia control efficacy of Ortho-K lenses

BACKGROUND: The goal of this study was to reproduce a three-dimensional representation of corneal defocus characteristics after orthokeratology (Ortho-K) treatment via an indicator defined as the weighted Zernike defocus coefficient of the treatment zone (C(weighted defocus)). This could be used to predict the effectiveness of Ortho-K treatment quantitatively in a timely manner after the one-month visit. METHODS: Seventy myopic children with axial length (AL) elongation after Ortho-K treatment (group A) and 63 myopic children with AL shortening after Ortho-K treatment (group B) were included in this one-year retrospective study. The proposed indicator was calculated by a customized MATLAB program. Multivariate binomial logistic regression and multivariate linear regression analyses were used to explore the association between AL change and the C(weighted defocus), age, sex, and other ocular biometric parameters. RESULTS: The 12-month AL change, age, pupil diameter, and vertical decentration of the Ortho-K lens were significantly different between the two groups. Multivariate logistic regression analysis showed that a larger C(weighted defocus) (≥ 0.35 D/mm(2)) (OR: 0.224; 95% CI: 0.078–0.646; P = 0.006) was correlated with the emergence of AL shortening after orthokeratology treatment. A multivariate linear regression model showed that a greater C(weighted defocus) was associated with slower 12-month AL elongation (β = − 0.51, P = 0.001). CONCLUSIONS: The C(weighted defocus) is an effective predictive indicator of myopia control, and a larger C(weighted defocus) may lead to slower elongation of AL. This meaningful indicator may help in the evaluation and adjustment of Ortho-K lens parameters in a timely manner and minimize the cost of clinical trial and error.