Early Changes in Ocular Biometry Predict Long-Term Treatment Outcomes Following Repeated Low-Level Red-Light Therapy

• Early axial length (AL) dynamics within the first 3 months strongly predict long-term prognosis after RLRL therapy in myopic children. • Both 1-month and 3-month AL changes, and the rate of AL change over the first 3 months, showed high prognostic performance (AUCs > 0.90) when adjusted for age and sex. • Early monitoring of AL provides a practical approach for individualized treatment response, helping identify children less likely to achieve optimal myopia control with RLRL therapy. Repeated low-level red-light (RLRL) therapy has emerged as a promising intervention for pediatric myopia control. However, substantial inter-individual variability in treatment response limits its clinical applicability. Reliable tools for early identification of long-term responders remain limited. This study aimed to develop a prognostic model based on early axial length (AL) dynamics to predict long-term myopia control outcomes in children undergoing RLRL therapy. This retrospective cohort study included myopic children treated with RLRL therapy at Xi'an No.1 Hospital between August 2022 and December 2025. Participants were classified into good- and poor-prognosis groups based on yearly AL change (≤ −0.06 vs. > −0.06 mm/year). Demographic characteristics, baseline spherical equivalent (SE), subfoveal choroidal thickness (sChT), and ocular biometric parameters at baseline and at 1 and 3 months post-treatment were collected. Univariable logistic regression was used to screen potential predictors, and nomograms were constructed for prognostic modeling. A total of 69 children were enrolled (35 good-prognosis, 34 poor-prognosis). Significant differences were observed in baseline SE, AL, 1-month AL change, 3-month AL change, and the AL change rate over the first 3 months (all P < 0.05). The nomogram incorporating age, sex, and 3-month AL change showed the highest predictive performance, with an AUC of 0.961. No serious adverse events were observed during follow-up. RLRL therapy is effective and safe for controlling myopia progression in children. Early AL dynamics, combined with baseline ocular parameters, provide strong predictive power for long-term outcomes, supporting individualized myopia management and risk-stratified clinical decision-making.