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  • Testing Different LRL Powers for Myopia Control

    By Lynda Seminara
    Selected by Russell N. Van Gelder, MD, PhD
    Refractive Mgmt/Intervention
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    Journal Highlights

    Ophthalmology, January 2024

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    The optimal power of low-level red light (LRL) for controlling myopia pro­gression has not been established. In a randomized controlled study, Zhou et al. compared three powers of LRL in children with myopia (0.37, 0.60, and 1.20 mW). All three resulted in signifi­cantly favorable effects on axial length (AL) elongation and spherical equiva­lent (SE), with no clinically meaningful differences between them.

    The study was a single-center, single-masked analysis of data for children aged 6 to 15 years with myopia (–0.50 D or more) and astigmatism (–2.50 D or less). Enrollment occurred in April and May of 2022. Each participant was assigned randomly (1:1:1:1) to one of the three power-level groups or the control group. The intervention was administered twice daily, for three minutes per session, with at least four hours between sessions. The main outcome measures were mean chang­es in AL, SE, and subfoveal choroidal thickness (SFCT). Follow-up concluded in December 2022.

    The study population consisted of 200 children who wore single-vision spectacles. By six months, SE progres­sion was signifi­cantly slower (all p < .001) in each intervention arm versus the control group: 0.01 D for 0.37 mW, –0.05 for 0.60 mW, 0.16 D for 1.20 mW, and –0.22 D for controls. AL changes were significantly smaller in each LRL group relative to controls (0.04 mm, 0.00 mm, –0.04 mm, and 0.27 mm, re­spectively; all p < .001). The increases in SFCT were sig­nificantly greater with LRL therapy (22.63 μm, 36.17 μm, 42.59 μm, and –5.07 μm, respectively; all p < .001). No adverse events were observed in any study arm.

    Although there were no significant differences in outcomes among the three levels of therapy, a trend toward better efficacy with higher power was observed. The authors affirmed that “larger-scale samples and longer-term follow-up studies are needed for identifying the optimal power settings for LRL therapy.” They noted the importance of balancing safety and effectiveness in determining the ideal power level.

    The original article can be found here.