Findings: In this randomized clinical trial including 278 school-aged children with premyopia, the incidence of myopia was lower among children receiving RLRL therapy than among controls.

Meaning: Exposure to RLRL is a novel and effective intervention for myopia prevention among children with premyopia, with good user acceptability and safety.

Importance: Myopia is a global concern, but effective prevention measures remain limited. Premyopia is a refractive state in which children are at higher risk of myopia, meriting preventive interventions.

Objective: To assess the efficacy and safety of a repeated low-level red-light (RLRL) intervention in preventing incident myopia among children with premyopia.

Design, Setting, & Participants: This was a 12-month, parallel-group, school-based randomized clinical trial conducted in 10 primary schools in Shanghai, China. A total of 139 children with premyopia (defined as cycloplegic spherical equivalence refraction [SER] of −0.50–0.50 diopter (D) in the more myopic eye and having at least 1 parent with SER ≤−3.00 D) in grades 1–4 were enrolled between April 1, 2021, and June 30, 2021; the trial was completed August 31, 2022.

Interventions: Children were randomly assigned to 2 groups after grade stratification. Children in the intervention group received RLRL therapy twice per day, 5 days per week, with each session lasting 3 minutes. The intervention was conducted at school during semesters and at home during winter and summer vacations. Children in the control group continued usual activities.

Main Outcomes & Measures: The primary outcome was the 12-month incidence rate of myopia (defined as SER ≤−0.50 D). Secondary outcomes included the changes in SER, axial length, vision function, and optical coherence tomography scan results over 12 months. Data from the more myopic eyes were analyzed. Outcomes were analyzed by means of an intention-to-treat method and per-protocol method. The intention-to-treat analysis included participants in both groups at baseline, while the per-protocol analysis included participants in the control group and those in the intervention group who were able to continue the intervention without interruption by the COVID-19 pandemic.

Results: There were 139 children (mean [SD] age, 8.3 [1.1] years; 71 boys [51.1%]) in the intervention group and 139 children (mean [SD] age, 8.3 [1.1] years; 68 boys [48.9%]) in the control group. The 12-month incidence of myopia was 40.8% (49⁄120) in the intervention group and 61.3% (68⁄111) in the control group, a relative 33.4% reduction in incidence. For children in the intervention group who did not have treatment interruption secondary to the COVID-19 pandemic, the incidence was 28.1% (9⁄32), a relative 54.1% reduction in incidence. The RLRL intervention statistically-significantly reduced the myopic shifts in terms of axial length and SER compared with the control group (mean [SD] axial length, 0.30 [0.27] mm vs 0.47 [0.25] mm; difference, 0.17 mm [95% CI, 0.11–0.23 mm]; mean [SD] SER, −0.35 [0.54] D vs −0.76 [0.60] D; difference, −0.41 D [95% CI, −0.56 to −0.26 D]). No visual acuity or structural damage was noted on optical coherence tomography scans in the intervention group.

Conclusions & Relevance: In this randomized clinical trial, RLRL therapy was a novel and effective intervention for myopia prevention, with good user acceptability and up to 54.1% reduction in incident myopia within 12 months among children with premyopia.

…(1) Input power <100VA, input voltage: AC10V-240V, 50Hz/60Hz 版本号 8 : 2.0，20200120 版 (2) Low-level single-wavelength red-light wavelength: 650nm±10nm (3) Diameter of low-level single-wavelength red-light cursor: 7mm±3mm, spot at the observation port: 10mm ± 2mm (4) Light source output power: 2.0mW±0.5mW; At a distance of 100mm: 1.07–1.42mw

…the intervention group are treated with the intervention instrument twice a day from Monday to Friday, 3 minutes each time, with an interval of at least 4 hours (morning break before school and afternoon break before school), under the supervision of the school teacher/coordinator in addition to routine study and life. All children have a unique corresponding personal account and password. They need to swipe the card and log in the system for verification before starting the intervention device…the optical energy will stop automatically after 3 minutes of use, leave the blue eye patch, close your eyes and rest for 3–5 minutes until the light spots before your eyes disappear.

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