Long-term effects of repeated low-level red light therapy with or without defocus incorporated multiple segment...

To evaluate the long-term impacts of repeated low-level red light (RLRL) alone or combined with defocus incorporated multiple segments (DIMS) lenses on axial length (AL), choroidal thickness (CT), and peripapillary retinal nerve fiber layer (RNFL) thickness in myopic children.

In this two-year retrospective study conducted at Wuhan Children's Hospital between January 2022 and April 2025, 49 children received combination treatment and 79 received RLRL therapy. Longitudinal changes of AL, subfoveal CT, and RNFL thickness were analyzed using linear mixed-effects models.

The AL change rate over 12 months was -0.014 mm/month (95% CI, -0.017 to -0.011) in the RLRL+DIMS group and -0.009 mm/month (95% CI, -0.011 to -0.006) in the RLRL-alone group (P = 0.002), with the between-group difference remaining significant at 24 months (P < 0.001). CT thickening was significantly greater in the combination group at both 12 months [5.51 μm/month (95% CI, 4.81 to 6.22) vs. 4.05 μm/month (95% CI, 3.54 to 4.57), P = 0.001] and 24 months [3.25 μm/month (95% CI, 2.88 to 3.62) vs. 2.34 μm/month (95% CI, 2.07 to 2.60), P < 0.001]. Temporal inferior (TI) RNFL thickness increased significantly in both groups at 12 months, with no significant intergroup difference.

RLRL therapy, either alone or combined with DIMS lenses, was associated with AL shortening and CT thickening, which were more pronounced with DIMS lenses. RNFL TI thickening was observed during the first 12 months. These findings support the potential long-term utility of RLRL-based myopia control strategies.