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 μm 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.