Myopia Control Effect of Repeated Low-Level Red-Light Therapy Combined with Orthokeratology: A Multicenter Randomized Controlled Trial

Abstract

Purpose: To investigate the efficacy and safety of repeated low-level red-light(RLRL) therapy combined with orthokeratology(Ortho-k) among the children who, despite undergoing Ortho-k treatment, exhibited an axial elongation of at least 0.50mm over 1 year.

Design: Multicenter, randomized, parallel-group, single-blind clinical trial (ClinicaTrials.gov,NCT04722874).

Participants: Eligible children were aged 8-13 years with a cycloplegic spherical equivalent refraction of -1.00 to -5.00 diopters in the initial Ortho-k fitting examination and had annual axial length (AL) elongation ≥ 0.50 mm despite undergoing Ortho-k for 1 year. A total of 48 children were enrolled from March 2021 to January 2022, and the final follow-up was completed in March 2023.

Methods: Children were randomly assigned to the RLRL combined with Ortho-k(RCO) or the Ortho-k group in a 2:1 ratio. The Ortho-k group wore Ortho-k at least 8 hours per night, while the RCO group received daily RLRL therapy twice a day for 3 minutes in addition to Ortho-k wearing.

Main outcome measures: The primary outcome was AL change measured at 12 months relative to baseline. The primary analysis was conducted in children who received the assigned intervention and completed at least 1 post-randomization follow-up using the modified intention-to-treat principle.

Results: A total of 47(97.9%) children were included in the analysis (30 in the RCO group and 17 in the Ortho-k group). The mean axial elongation rate before the trial was 0.60mm/year in the RCO group and 0.61mm/year in the Ortho-k group. After 12 months following the intended intervention, the adjusted mean AL changes were -0.02mm(95% CI, -0.08 to +0.03 mm) in the RCO group and 0.27mm(0.19-0.34 mm) in the Ortho-k group. The adjusted mean difference in AL change was -0.29mm(-0.44 to -0.14mm) between the RCO and Ortho-k groups. The percentage of children achieving an uncorrected visual acuity greater than 20/25 was similar in the RCO (64.3%) and Ortho-k (65.5%) groups (Chi2 test, P=0.937).

Conclusions: Combining RLRL therapy with Ortho-k may offer a promising approach to optimize axial elongation control among myopic children. This approach also potentially allows children to achieve satisfactory visual acuity, reducing the daytime dependence on corrective eyewear.

Keywords: Myopia Control; Orthokeratology; Randomized controlled trial; Repeated Low-Level Red-Light Therapy.