Long-term effect of repeated low-level red light therapy on myopia control: A systematic review and meta-analysis

Introduction Myopia is a refractive error where distant objects are not clearly seen and appear blurred. Goal of this study was to evaluate long-term effectiveness of Repeated Low-Level Red Light (RLRL) therapy for children with myopia, which primarily focused on Axial length (AL) and Spherical Equivalent Refraction (SER) as primary endpoints. Methods The research compared outcomes between RLRL treatment with Single Vision Spectacles (SVS) for childhood myopia management. We performed a systematic literature search in the PubMed, Embase and Cochrane databases using “Myopia” and “ Repeated Low-Level Red Light “. Mean differences (MD) were estimated and the effects of therapies measured. Publication bias and heterogeneity analysis were carried out by Inverted Precision Effect Test-Precision Effect Estimate Standard Error (PET-PEESE) (and subsequent Search Sequential Analysis) and Tau test. Bayesian meta-analysis was performed using Jaffrey Amazing Statistical Package (JASP). Results This meta-analysis comprised 1,714 participants: 824 in RLRL and 890 in SVS group. Pooled effect size for AL reduction was 0.953 ± 0.294, (95% credible interval (CI) 0.775 to 0.980). Pooled effect size for SER reduction was 1.521 ± 0.662 (95% CI 0.102 to 2.736). PET-PEESE analysis revealed no significant publication bias ( p-value 0.407). Random effects models were employed for presence of significant heterogeneity (3.9 and 5.7 for AL; 5.7 for SER), alongside degree of variation (0.828 & 1.665) for Tau (τ), which estimates the between-study variance. Conclusion Long-term observations indicate that RLRL treatment significantly influences myopia management, leading to considerable reductions in both AL and SER. Additional research is essential to investigate potential long-term rebound effects.