Effects of low-level LED red-light therapy on axial elongation in hyperopic children: A bidirectional cohort study

• Low-level LED red-light therapy significantly accelerates axial elongation in hyperopic children. • In anisometropic hyperopic children, unilateral LED red-light therapy promotes axial growth in the lagging eye, reducing interocular disparity. • Findings suggest a refractive state–dependent bidirectional effect of red light on ocular growth. • LED red-light therapy may serve as a safe and non-invasive approach to promote emmetropization in hyperopic children. To investigate whether low-level LED red-light therapy promotes axial elongation in hyperopic children. This bidirectional cohort study included 201 hyperopic children aged 4 -13 years. Participants were divided into two groups: the LED group (n = 51), who received low-level LED red-light therapy, and the spectacle-only comparison group (n = 150). Axial length (AL) was measured at baseline and each follow-up. Longitudinal changes in AL were analyzed using a linear mixed-effects model (LMM). Inverse probability of treatment weighting (IPTW) was performed as a sensitivity analysis to minimize potential confounding. In a subgroup of 40 anisometropic children who received unilateral LED treatment, interocular comparisons between treated and fellow eyes were conducted using paired t -tests, and within-subject LMM analyses to assess eye-specific treatment effects. The LED group showed a significantly faster rate of axial elongation than the comparison group (interaction β=+0.082 mm/year, 95% CI: 0.042 to 0.122; p < 0.001). In the anisometropic subgroup, treated eyes elongated significantly faster than fellow eyes (mean difference = +0.167 mm/year, 95% CI: 0.109–0.226; p < 0.001), leading to a reduction in interocular axial length disparity. LMM confirmed a greater time-dependent increase in treated eyes (β = +0.151 mm/year, 95% CI: 0.102–0.199; p < 0.001). Low-level LED red-light therapy significantly accelerates axial elongation in hyperopic children and reduces interocular differences in anisometropic cases, suggesting that it may promote more balanced binocular refractive development.