Six-month repeated irradiation of 650 nm low-level red light reduces the risk of myopia in children: a randomized controlled trial

Abstract

Purpose: To evaluate whether the six-month repeated irradiation of 650 nm low-level red light (LLRL) decreases the risk of myopia onset in children.

Methods: This was a single-masked, randomized controlled trial. A total of 112 children (aged 6-12 years) were enrolled and randomized to the treatment group or control group in a 1:1 ratio. The cycloplegic spherical equivalent error (SER) of children at baseline was -0.5 diopter (D) to 3D. Children in the treatment group were irradiated with the 650 nm LLRL for 6 min daily. No intervention was given to the control. The primary outcomes are myopia incidence, change in cycloplegic SER, and change in axial length (AL).

Results: For the treatment group and control group, the six-month myopia incidence rates were 1.8% (95% confidence interval, CI: 0.2-4.9%) and 12.5% (95% CI: 5.5-21.9%), respectively. The difference was significant (p = 0.028). The median changes in AL for the treatment group and control group were -0.02 (interquartile range, IQR: -0.12 to 0.06) mm, and 0.09 (IQR: 0-0.18) mm, respectively. The difference was significant (p < 0.001). The median changes in cycloplegic SER for the treatment group and control group were 0 (IQR: 0-0.25) D, and -0.125 (IQR: -0.375 to 0) D, respectively. The difference was significant (p < 0.001). There was no adverse event.

Conclusion: The repeated irradiation of 650 nm LLRL may have a strong effect for myopia prevention in children, without risk of adverse events.

Trial registration: this trial is retrospectively registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ), the registration number is ChiCTR2200058963.

Keywords: Children; Myopia; Prevention; Randomized controlled trial; Red light.