The Rebound Effect on Repeated Low-Level Red Light Therapy for Myopia: A Randomized Controlled Clinical Trial

Myopia is a public health issue of global concern, with its incidence and severity increasing annually, particularly among children and adolescents. Projections indicate that by 2050, the global prevalence of myopia will reach as high as 49.8%, with the prevalence of high myopia reaching 9.8% .With the rising prevalence of myopia, the risk of myopia-related complications has increased significantly, including cataracts, glaucoma, myopic macular degeneration, and retinal detachment. Without proper management, these conditions can lead to severe visual impairment and substantial societal burdens. Therefore, preventing and slowing the onset and progression of myopia has become a critical strategy in myopia control efforts.

Repeated low-level red light (RLRL) therapy is an emerging treatment modality for myopia control. In a 12-month multicenter randomized clinical trial, the RLRL group demonstrated a 69.4% reduction in axial length elongation and a 76.6% decrease in myopic refractive progression compared to the single-vision spectacle (SVS) group. Furthermore, RLRL therapy showed superior efficacy in patients with high myopia, achieving an axial length reduction of over 0.05 mm in 53.3%-59% of cases.Comparative studies on the efficacy of atropine in controlling myopia demonstrated that, after 12 months of use, the RLRL therapy significantly outperformed 0.01% atropine in controlling axial length.In myopic patients who still exhibit poor control of axial length despite wearing orthokeratology lenses, combined use of RLRL therapy significantly inhibits axial growth.

Given that myopia typically progresses continuously during childhood, Xiong et al. investigated the long-term efficacy and safety of RLRL therapy over a period exceeding two years. The results demonstrated good tolerability of RLRL therapy, with an efficacy rate of 75% in terms of axial length reduction and myopic refractive control after two years of treatment; however, the therapeutic efficacy declined in the second year compared to the first year.Additionally, similar to other myopia intervention strategies, a rebound effect was observed in patients who discontinued RLRL treatment after one year; in these patients, their myopia progression rate during the second year was comparable to the progression level observed in the SVS group during its first year.

To further investigate the long-term efficacy of RLRL treatment and rebound effects after treatment discontinuation, as well as to explore strategies for mitigating these rebound effects, this study focused on participants who received continuous RLRL therapy for one year. It examined the rebound effects in axial length (AL) and spherical equivalent refractive power (SER) among participants who discontinued or gradually reduced RLRL treatment compared to those who continued treatment.