December 1, 2022
By Dwight Akerman, OD, MBA, FAAO, FBCLA, FIACLE
Increased time spent outdoors in bright light has been established as an effective protective factor for myopia development. Several clinical trials and animal model research have confirmed the protective effect of exposure to bright outdoor light and its dose-response relationship. Experts recommend a minimum of 120 minutes of intermittent outdoor light exposure per day for children and adolescents, including recess time, physical education time, and additional outdoor time after school (Wu et al., 2020, Ho et al., 2019, Lan et al., 2014, Deng et al., 2019).
Researchers have also proposed renovating classrooms and installing glass walls and ceilings to increase the intensity and duration of protective bright light exposure for students. However, these strategies often are expensive and pragmatically challenging.
Repeated low-level red light (RLRL) is an emerging therapy for myopia progression control in children and adolescents. Through several clinical trials, the intervention has shown to be a promising method of addressing juvenile-onset myopia. For example:
- Jiang et al., 2022 conducted a prospective 12-month, multicenter, randomized, parallel-group, single-blind clinical trial to assess the efficacy and safety of RLRL therapy for myopia control. The researchers proposed delivering light directly to the retina for short periods (three minutes per session, twice daily with a minimum interval of four hours, five days per week) through a desktop device that emits red light at a wavelength of 650 nm. Their data showed that the treatment is effective, safe, and highly acceptable to users. The researchers noted that double-masked, placebo-controlled studies of low-level red-light therapy are needed to evaluate long-term efficacy and safety, to look for possible rebound effects, and to determine optimal device settings and treatment regimens.
- Because many RLRL studies have lacked adequate control groups, Dong et al., 2022 recently assessed the efficacy and safety of RLRL through the first sham device-controlled, randomized, double-blind clinical trial. They found that the treatment was safe and that the children treated with RLRL at 100% power had significantly reduced myopia progression and axial elongation over six months compared with those who received treatment via a sham device at 10% power. The researchers noted that these findings contribute to the evidence that RLRL therapy is an effective and safe intervention against myopia progression. They suggest that future studies focus on evaluating the potential dose-response relationship and optimal treatment intensity.
Interestingly, shorter wavelengths of light have also been studied as a therapy for juvenile-onset myopia. Torii et al., 2022 propose that violet light (VL), 360-400 nm wavelength, is also an effective element in reducing the progression of myopia. These researchers investigated the safety and efficacy of novel eyeglasses that emit VL from eyeglass frames in a double-masked, randomized, pilot clinical trial conducted over six months at a single site in Japan. A total of 43 children aged 6-12 years were randomized in the clinical trial. The exposure time was three hours per day. No significant differences were seen in any safety evaluation. Significant changes were seen in axial elongation, choroidal thickness, and cycloplegic refractions in the subgroup analysis of 8- to 10-year-old children; otherwise, no significant differences were observed.
Myopia development and progression are multifactorial, with a complex interaction between genetic (non-modifiable) and environmental (modifiable) risk factors influencing myopigenesis. Most children, especially those living in an urban environment, live in a myopigenic environment (high near work, low time outdoors). They are almost continuously exposed to myopia-inducing stimuli.
There is a need for consensus on optimal, feasible, and noninvasive light interventions for myopia progression control, whether through increased time outdoors, adapted architectural lighting, or light-therapy devices.
Best professional regards,
Dwight H. Akerman, OD, MBA, FAAO, FBCLA, FIACLE
Chief Medical Editor