Let there be light: Repeated red-light therapy feasible for myopia control in kids

Repeated, direct delivery of light on the retina can put brakes on axial elongation and myopic refraction progression in children with nearsightedness, according to a team of investigators from China.

Lifestyle has been established to play a big role in the development of myopia in young people. There is decreased exposure to outdoor light and excessive time spent indoors under artificial lights with near-work activities. Intervention trials that examined the effect of increasing exposure to outdoor bright light in China and Taiwan support this idea. [JAMA 2015;314:1142-1148; Ophthalmology 2018;125:1239-1250; Ophthalmology 2013;120:1080-1085]

“Since then, researchers have proposed renovating classrooms and installing glass walls and ceilings as a means to increase the intensity and duration of protective bright light exposure for students, although these strategies are often expensive and pragmatically challenging,” the investigators said. [PLoS One 2017;12:e0181772; Ophthalmic Physiol Opt 2015;35:252-262]

“As an alternative to increasing bright light exposure, we propose to deliver light on the retina directly at a much shorter duration of exposure, but repeatedly, for myopia control. We intend to use a device that emits red light at 650 nm in wavelength based on the fact that it has already been approved and widely used for amblyopia treatment in China so that the safety of the participants can be potentially maximized,” they said.

Good alternative to glasses

In a trial, the investigators randomized 264 children (mean age 10.5 years, 49.2 boys) to undergo repeated low-level red-light (RLRL) therapy and wear single vision spectacle (SVS; n=119) or wear SVS only (control; n=145). These children had myopia of cycloplegic spherical equivalent refraction (SER) of –1.00 to –5.00 dioptres (D), astigmatism <2.50 D, anisometropia <1.50 D, and best-corrected visual acuity (BCVA) >0.0 logMAR (Snellen 1.0 or 20/20).

The RLRL treatment was delivered using a desktop light therapy device which emits red light of 650 nm in wavelength, at an illuminance level of approximately 1,600 lux, and a power of 0.29 mW for a 4-mm pupil. Each session lasted 3 minutes, conducted twice per day with a minimum interval of 4 hours. Treatment was administered 5 days per week for 12 months.

A total of 246 children were included in the analysis, 117 in the RLRL and 129 in the control group. The key outcomes were more favourable among children in the RLRL group. Specifically, the adjusted 12-month axial elongation and SER progression were 0.13 mm and –0.20 D with RLRL vs 0.38 mm and –0.79 D with the control. [Ophthalmology 2021;doi:10.1016/j.ophtha.2021.11.023]

The between-group difference was 0.26 mm (95 percent confidence interval [CI], 0.20–0.31) in axial elongation and –0.59 D (95 percent CI, –0.72 to –0.46) in SER progression.

Based on the data, the investigators concluded that RLRL therapy is an effective new alternative treatment for myopia control with good user acceptability and no documented functional and structural damages.