Repeated low-level red-light therapy for childhood myopia: Efficacy, mechanisms, rebound effects, safety boundaries,...

Repeated low-level red-light therapy (RLRL) has emerged as a promising ocular photobiomodulation strategy for childhood myopia control. Published randomized trials have reported substantial reductions in axial elongation and refractive progression, and some studies have described apparent axial shortening during active treatment. However, the rapid clinical adoption of RLRL has raised important questions regarding mechanism, rebound after discontinuation, device-specific safety, and standardized clinical implementation. This structured narrative review summarizes current evidence on RLRL for childhood myopia, with emphasis on efficacy, biological plausibility, choroidal responses, rebound effects, retinal safety, device dosimetry, and regulatory considerations. The strongest mechanistic evidence in children supports rapid choroidal thickening and increased choroidal perfusion after RLRL, whereas mitochondrial photobiomodulation, dopamine signaling, and scleral remodeling remain biologically plausible but incompletely verified pathways. Follow-up studies have documented rebound axial elongation after treatment cessation, although cumulative benefits may partly persist. Clinical trial safety findings are generally reassuring, but case reports of retinal injury, transient optical coherence tomography (OCT) abnormalities, cone-level changes, and independent radiometric evaluations indicate that safety cannot be generalized across all red-light devices. RLRL should therefore be interpreted as a device-dependent intervention rather than a uniform treatment category. Future studies should prioritize independent multicenter trials, standardized radiometric reporting, masked retinal imaging review, long-term safety surveillance, and clinically practical protocols for treatment initiation, monitoring, and discontinuation.

Repeated low-level red-light therapy (RLRL) has become a prominent nonpharmacological approach for controlling childhood myopia progression, particularly in East Asia. The current clinical evidence includes randomized trials in children with established myopia, premyopia, and high myopia, as well as studies evaluating its adjunctive use with orthokeratology, accompanied by an expanding body of mechanistic and safety-related research.

This structured narrative review synthesized evidence on repeated low-level red-light therapy (RLRL) for childhood myopia from PubMed/MEDLINE, Embase, Web of Science, the Cochrane Library, and Scopus from database inception to May 22, 2026. Suggested search terms included combinations of "myopia," "child*," "premyopia," "red light," "low-level red light," "repeated low-level red-light," "photobiomodulation," "axial length," "spherical equivalent," "choroid," "safety," "retinal damage," "dosimetry," "radiometry," and "rebound." Reference lists of relevant reviews and key primary studies were manually screened to identify additional records. Priority was given to randomized clinical trials, prespecified follow-up studies, imaging-based mechanistic studies, laboratory safety evaluations, systematic reviews, and official regulatory or journal guidance. Because device parameters were incompletely reported in parts of the literature and the original working draft did not specify a reproducible search strategy, the present article is presented as a structured narrative review rather than a formal systematic review or meta-analysis.

Short-term efficacy has been consistently favorable in published randomized controlled trials (RCTs), with several studies reporting substantially less axial elongation than spectacles or sham controls, and some even demonstrating measurable axial shortening. The strongest human mechanistic evidence points to rapid choroidal thickening and increased choroidal perfusion. Broader photobiomodulation biology supports mitochondrial and vascular hypotheses, whereas dopamine-mediated and scleral-remodeling pathways remain largely inferential. Rebound after treatment cessation has now been documented, particularly for axial length. Safety findings remain mixed: clinical trial data are generally reassuring, but isolated reports of retinal injury, transient OCT lesions, cone-density changes, and independent device-radiometry studies all suggest that caution remains necessary.

RLRL may be among the most effective myopia-control strategies currently under investigation in the short term, but the field has not yet reached full clinical maturity. The existing evidence is geographically concentrated, device-specific safety validation remains incomplete, and the long-term boundaries of ocular safety are still uncertain. Therefore, clinical application should be standardized, guided by retinal imaging, and evaluated according to specific device parameters rather than generalized to all "red-light" products.