Ortho-K Peripheral Refraction Parameters Can Predict Axial Elongation Rate

Peripheral myopic defocus induced by ortho-K lenses may be a primary mechanism for slowing axial elongation. The current study found that the minimum defocus distance formed by ortho-K lens reshaping was significantly positively correlated with the monthly axial elongation rate. The minimum defocus distance appears to reflect the degree of defocus decentration to a certain extent; that is to say, the greater the decentration, the smaller the minimum defocus distance and the slower the axial elongation. Photo: Langis Michaud, OD. Click image to enlarge. Orthokeratology (ortho-K) lenses are an important tool in controlling myopia progression. By altering the corneal morphology and creating relative peripheral myopic defocus on the retina, these lenses are thought to slow myopia progression.Researchers in China recently assessed the peripheral relative defocus state within a 150° visual field in children wearing ortho-K lenses using a type of imaging called multispectral refraction topography, which measures refractive power across the visual field. Their study, which was published in Contact Lens & Anterior Eye, presented a complete horizontal profile of the typical myopic defocus ring for the first time and defined the associated positional and morphological parameters of the defocus ring. Axial elongation rate showed a negative correlation with defocus ring outer diameter and defocus ring width, while it was positively correlated with minimum defocus distance and defocus ring inner diameter.While their study did not establish causality, the research team stated that their findings “suggested that optimizing ortho-K lens design should focus on creating a retinal defocus area that is wider and closer to the posterior pole to enhance myopia control efficacy.”Wide-angle (150° field of view) relative peripheral refraction and axial length measurements were conducted in 48 children wearing ortho-K lenses. Key peripheral refraction parameters included minimum defocus distance, defocus ring outer diameter, defocus ring inner diameter, defocus ring width and retinal relative defocus values.The current study found that the mean inner diameter of the defocus ring was 49.30º of field angle, which showed a significant positive correlation with the monthly axial elongation rate. Thus, a smaller inner diameter was associated with slower axial elongation, suggesting that ortho-K lenses with smaller optical zones are more effective in controlling myopia progression. Age, baseline axial length, defocus ring width, minimum defocus distance and relative defocus value (45–53) were five predictors in the multivariable prediction model.“The proposed regression model based on peripheral retinal defocus parameters demonstrated moderate predictive power for estimating axial elongation rates, which may support individualized myopia control strategies in clinical practice,” the study authors wrote in their paper.”They believe their predictive framework could help clinicians forecast the treatment response at an early stage; if the predicted outcome is unsatisfactory, timely adjustments to lens design or the addition of low-dose atropine therapy could be considered to maximize the efficacy of myopia control.“This predictive approach highlights the potential for more precise, personalized myopia management strategies in the future,” they noted. “Future research should include multicenter cohorts, larger sample sizes, and longer follow-up to validate and refine the current predictive model.” Click here for the journal source. Mandantuoya, Ao M, Zhang Y. The relationship between relative peripheral refraction and axial length elongation in myopic children wearing orthokeratology lenses using a novel wide-angle multispectral refraction topographer. Cont Lens Anerior Eye. October 13, 2025. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.