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

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.