Red Light Therapy Induces Choroidal Thickening, Potentially Slowing Myopia

Repeated low-level red-light therapy can result in sustained macular choroidal thickening in children with myopia throughout their treatment duration, according to research published in Ophthalmology. These thickness changes can predict 1-year myopia control efficacy after 3 months. 

Researchers included 120 children (age range, 8-13 years; 55 boys) with myopia in a multicenter, randomized, controlled trial to investigate macular choroidal thickness (mCT) changes spanning 1 year after assigning them to repeated low-level red-light therapy (n=60) or single vision spectacle lens wear (n=60). Patients underwent visual acuity, axial length, and mCT measurements at baseline and at follow-up visits conducted at 1, 3, 6, and 12 months. All participants wore single vision spectacles throughout the study and updated them when necessary. Participants in the repeated low-level red-light therapy group received treatment for 3 minutes per session, 2 sessions per day, 5 days per week, in addition to wearing their spectacle correction.

Children who underwent repeated low-level red-light therapy experienced significant macular choroidal thickening at 1 month with a change of 14.755 μm (95% CI, 10.450-19.060). While the magnitude of choroidal thickening experienced a mild decrease at months 3 and 6, mean mCT was 9.089 μm thicker at 12 months compared with baseline. 

Mean mCT significantly decreased in individuals in the single vision spectacle group. Changes in mean mCT were -1.111 μm (95% CI, -5.680 to 3.458) at 1 month, -8.212 μm (95% CI, -13.194 to -3.231) at 3 months, -10.190 μm (95% CI, -17.740 to -2.640) at 6 months, and -10.407μm (95% CI, -15.212 to -5.602) at 12 months, according to the report. 

Children treated with repeated low-level red-light experienced less axial progression (0.122 vs 0.379 μm) and spherical equivalent refraction change (SER; -0.224 vs -0.799) compared with control group participants for1 year (P <.001 for both).

“[A]s early as one month after [repeated low-level red-light therapy], macular choroidal thickening reached its peak magnitude and was associated with 12-month myopia control efficacy,” according to the researchers. “Acceptable predictive discrimination of satisfactory treatment efficacy of RLRL therapy was obtained based on initial 3-month mCT changes. Macular CT may be a proxy for future treatment response and serve as a reference for guiding treatment regimens.” 

Study limitations include a small sample size, high loss to follow-up, and homogeneity among the cohort.