Low-intensity, long-wavelength red light slows the progression of myopia in children: an Eastern China-based cohort

Purpose To determine the effect of low-intensity, long-wavelength red light therapy (LLRT) on the inhibition of myopia progression in children. Methods A retrospective study was conducted. One hundred and five myopic children (spherical equivalent refractive error [SER] -3.09 +/- 1.74 dioptres [D]; mean age, 9.19 +/- 2.40 years) who underwent LLRT treatment (power 0.4 mW, wavelength 635 nm) twice per day for 3 min each session, with at least a 4-h interval between sessions, and a control group of 56 myopic children (SER -3.04 +/- 1.66 D; mean age, 8.62 +/- 2.45 years) were evaluated. Both groups wore single-vision distance spectacles. Each child returned for a follow-up examination every 3 months after the initial measurements for a total of 9 months. Results At 9 months, the mean SER in the LLRT group was -2.87 +/- 1.89 D, significantly greater than that of the control group (-3.57 +/- 1.49 D, p < 0.001). Axial length (AL) changes were -0.06 +/- 0.19 mm and 0.26 +/- 0.15 mm in the LLRT group and control group (p < 0.001), respectively. The subfoveal choroidal thickness changed by 45.32 +/- 30.88 mu m for children treated with LLRT at the 9-month examination (p < 0.001). Specifically, a substantial hyperopic shift (0.31 +/- 0.24 D and 0.20 +/- 0.14 D, respectively, p = 0.02) was found in the 8-14 year olds compared with 4-7 year old children. The decrease in AL in subjects with baseline AL >24 mm was -0.08 +/- 0.19 mm, significantly greater than those with a baseline AL <= 24 mm (-0.04 +/- 0.18 mm, p = 0.03). Conclusions Repetitive exposure to LLRT therapy was associated with slower myopia progression and reduced axial growth after short durations of treatment. These results require further validation in randomised controlled trials.