Sex specific ocular parameter trajectories during low intensity red light exposure in myopic adolescents in Liaoning China

To describe, in the absence of a control group, sex-specific trajectories of ocular parameters during low-intensity red light exposure in myopic adolescents in Liaoning, China. Given the uncontrolled design, this study was exploratory and hypothesis generating. This prospective, non-randomized, uncontrolled cohort enrolled 180 myopic adolescents (90 males, 90 females). All participants used a 650 nm low-intensity red light device twice daily. Ophthalmic examinations were conducted at baseline and at 1, 3, 6, and 12 months. Repeated-measures analysis of variance assessed time effects, sex effects, and time × sex interactions. At baseline, males had longer axial length (24.35 ± 0.94 vs. 24.02 ± 0.79 mm; P = 0.014) and more myopic spherical equivalent (- 2.25 ± 1.46 vs. -1.70 ± 1.43 D; P = 0.011) than females, while baseline UDVA and intraocular pressure did not differ significantly (both P > 0.05). Over 12 months, axial length increased in both sexes (time effect P < 0.001) and spherical equivalent became less negative (time effect P < 0.001), but time × sex interactions were not significant for axial length or spherical equivalent (both P > 0.05). The between-sex difference in annual axial elongation was 0.01 mm (95% CI - 0.023 to 0.066). UDVA (decimal) increased over time (P < 0.01) with a small time × sex interaction (P < 0.05): females showed earlier increases (significant at 1 month), whereas males showed later increases (significant at 3 months). This uncontrolled, nonrandomized exploratory cohort describes 12-month trajectories of ocular parameters observed in adolescents undergoing low-intensity red light exposure. Without a comparator group, these observations cannot be attributed to the exposure and should be interpreted as descriptive and hypothesis generating.