Safety of and chorioretinal circulation during repeated low‐level red‐light therapy for myopic children

Abstract Background To evaluate the safety of repeated low‐level red‐light (RLRL) therapy in children, and the dynamic evolution of choroidal and retinal blood flow. Methods This is a single‐centre, randomised, single‐blind, parallel‐group clinical trial. Seventy myopic children were randomly assigned to either the intervention group [receiving RLRL therapy plus single‐vision spectacle (SVS)] or the control group (wearing SVS). Participants underwent comprehensive ophthalmic examinations following their first irradiation, 9 months continuous RLRL therapy and stop of treatment. Quantitative analyses of choroidal and retinal microcirculation were analysed via optical coherence tomography angiography. Results Over 9 months of treatment, while the RLRL treatment demonstrated significantly less increases in refractive error and axial length compared with the SVS treatment ( p s < 0.05), no abnormalities in fundus structure or visual function (mfERG, VEP and microperimetry) were detected ( p s > 0.05). A single red‐light exposure did not exert a significant influence on choroidal thickness ( p s > 0.05). Upon continuous treatment, the RLRL group achieved peak values in these circulations at 9 months ( p s < 0.05). Following cessation of exposure, all circulations exhibited a declining trend, reaching similar levels in both groups ( p s > 0.05). As the frequency of red‐light exposures intensified, there was a consistent surge in these circulations ( p s < 0.05). Conclusions Nine months of continuous RLRL exposure does not cause toxic side effects on retinal or optic nerve functions, and there is a time‐dependent cumulative response in choroidal and retinal circulation.