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

Abstract

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/mm²) (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.