Purpose: To assess the efficacy and safety of repeated low-level red-light (RLRL) therapy in myopia control in children.

Design: Multicenter, randomized, parallel-group, single-blind clinical trial.

Participants: 264 eligible children 8–13 years of age with myopia of cycloplegic spherical equivalent refraction (SER) of −1.00 to −5.00 diopters (D), astigmatism of 2.50 D or less, anisometropia of 1.50 D or less, and best-corrected visual acuity (BCVA) of 0.0 logarithm of the minimum angle of resolution or more were enrolled in July & August 2019. Follow-up was completed in September 2020. This trial is registered with ClinicalTrials.gov (identifier, NCT04073238).

Method: Children were assigned randomly to the intervention group (RLRL treatment plus single-vision spectacle [SVS]) and the control group (SVS). The RLRL treatment was provided by a desktop light therapy device that emits red light of 650-nm wavelength at an illuminance level of ~1600 lux and a power of 0.29 mW for a 4-mm pupil (class I classification) and was administered at home under supervision of parents for 3 minutes per session, twice daily with a minimum interval of 4 hours, 5 days per week.

Outcome Measures: The primary outcome and a key secondary outcome were changes in axial length and SER measured at baseline and the 1/3/6/12-month follow-up visits. Participants who had at least 1 post-randomization follow-up visit were analyzed for treatment efficacy based on a longitudinal mixed model.

Results: Among 264 randomized participants, 246 children (93.2%) were included in the analysis (117 in the RLRL group and 129 in the SVS group). Adjusted 12-month axial elongation and SER progression were 0.13 mm (95% confidence interval [CI], 0.09–0.17mm) and −0.20 D (95% CI, −0.29 to −0.11D) for RLRL treatment and 0.38 mm (95% CI, 0.34–0.42 mm) and −0.79 D (95% CI, −0.88 to −0.69 D) for SVS treatment. The differences in axial elongation and SER progression were 0.26 mm (95% CI, 0.20–0.31 mm) and −0.59D (95% CI, −0.72 to −0.46 D) between the RLRL and SVS groups. No severe adverse events (sudden vision loss ≥2 lines or scotoma), functional visual loss indicated by BCVA, or structural damage seen on OCT scans were observed.

Conclusions: Repeated low-level red-light therapy is a promising alternative treatment for myopia control in children with good user acceptability and no documented functional or structural damage.

[Keywords: axial length, myopia control, randomized clinical trial, repeated low-level red-light therapy, spherical equivalent refraction]

…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 this was already approved and is used widely for amblyopia treatment in China so that the safety of the participants can be potentially maximized. The selection of treatment method is also based on unpublished anecdotal findings from children who used the device for the purpose of amblyopia treatment, where increased choroidal thickness and blood flow and stabilization of axial elongation were observed. By the time of this manuscript’s preparation, a published report also demonstrated that this strategy, carried out using a similar device, statistically-significantly reduced the rate of myopia progression and axial length (AL) elongation over 6 months, similar to orthokeratology compared with single-vision spectacle (SVS) wear.¹¹ Herein, we report the results of a prospective, multicenter, randomized clinical trial to assess the efficacy and safety of repeated low-level red-light (RLRL) therapy in myopia control in children.

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