May 15, 2023
By Dwight Akerman, OD, MBA, FAAO, FBCLA, FIACLE
In recent years, repeated low-level red light (RLRL) therapy has emerged as a new myopia therapeutic intervention, particularly in China. However, few systematic reviews of its efficacy in reducing the course of pediatric myopia have been published. Recently, Tang et al. conducted a systematic review and meta-analysis based on a comprehensive review of the existing literature.
Red light refers to the visible light with a wavelength of 600-700 nm. RLRL can stimulate the production of dopamine, which is crucial for controlling eye growth, along with nitrous oxide (NO), which dilates blood vessels and increases blood flow.
Of the 13 studies (eight randomized controlled trials, three non-randomized controlled trials, and two cohort studies) involving children and adolescents with myopia, eight met the meta-analysis criteria. These studies included a total of 934 individuals, and eight reported the change in spherical equivalent refractive error (SER) and axial length (AL), while four reported the change in subfoveal choroid thickness. All 13 selected studies were conducted in China, and only studies written in English or Chinese were considered.
The weighted mean difference for myopia progression between repeated low-intensity red light treatment and the control group was 0.68D per six months for SER change, -0.35mm per six months for axial length elongation, and 36.04μm per six months for subfoveal choroid thickness change. None of the studies in this meta-analysis reported vision-threatening events, glare, flash blindness, or afterimages after treatment, and no structural damage was seen on the photosensory layer from OCT images.
The RLRL treatment scheduled in the included studies was all for three minutes per session, two treatment sessions per day, with a minimum interval of four hours between sessions. The wavelength and power of the red light used in each study varied, so it could not directly compare the effect of the treatment session on the efficacy of myopia control.
The researchers concluded that RLRL treatment may reduce myopia progression in refraction and axial length without significant adverse events. However, this evidence was low-certainty, and the rebound effect seems large after the discontinuation of RLRL. Therefore, longer-term, cumulative rebound effects and better and larger RCTs with two-year follow-up should be investigated further. In addition, more rigorously designed trials are needed to explore the optimal treatment protocol and parameters of RLRL.
Efficacy of Repeated Low-Level Red-Light Therapy for Slowing the Progression of Childhood Myopia: A Systematic Review and Meta-Analysis
Jie Tang, Ya Liao, Na Yan, Shiferaw Blen Dereje, Jingjing Wang, Yunjiao Luo, Yuhao Wang, Wen Zhou, Xiaojuan Wang, Wei Wang
Purpose: To evaluate the long-term efficacy and safety of repeated low-intensity red light (RLRL) treatment for childhood myopia.
Design: Systematic review and meta-analysis
Methods: We searched PubMed, Web of Science, CNKI, and Wanfang from inception to February 8, 2023. We used the RoB 2.0 and ROBINS-I tools to assess the risk of bias and then used a random-effect model to calculate the weighted mean difference (WMD) and 95% confidence intervals (CIs). The primary outcomes were WMD in spherical equivalent refractive error (SER), WMD in axial length (AL), and WMD in subfoveal choroid thickness (SFChT). Subgroup analyses were performed to investigate the sources of heterogeneity based on variation in follow-up and study design. Egger’s and Begg’s tests were used to assess publication bias. Sensitivity analysis was used to verify the stability. Only studies written in English or Chinese were considered.
Results: This analysis included 13 studies (eight randomized controlled trials, three non-randomized controlled trials, and two cohort studies) involving 1,857 children and adolescents. Eight studies met the meta-analysis criteria, and the WMD for myopia progression between RLRL and the control group was 0.68 D per 6 months (95%CI, 0.38 to 0.97 D; I2=97.7%; P<0.001) for SER change, -0.35mm per 6 months (95%CI, -0.51 to -0.19 mm; I2=98.0%; P<0.001) for AL elongation and 36.04 μm per 6 months (95%CI, 19.61 to 52.48 μm; I2=89.6%; P<0.001) for SFChT change.
Conclusions: Our meta-analysis shows that RLRL therapy may be effective in delaying the progression of myopia. The evidence is low certainty, and larger and better RCTs with two-year follow-ups are needed to improve the existing state of knowledge to inform medical guidelines more comprehensively.
Tang, J., Liao, Y., Yan, N., Dereje, S. B., Wang, J., Luo, Y., … & Wang, W. (2023). Efficacy of repeated low-level red-light therapy for slowing the progression of childhood myopia: A systematic review and meta-analysis. American Journal of Ophthalmology.