Axial Length Stabilization and Scleral Curvature Changes following Repeated Low-level Red-light Therapy in Children with High Myopia

Purpose: To determine the incidence and extent of axial length (AL) shortening after 12 months of repeated low-level red-light (RLRL) therapy in highly myopic eyes. In addition, to investigate the relationship between the AL shortening and changes in the posterior scleral curvature in the swept-source optical coherence tomographic (SS-OCT) images. Methods: Thirty participants aged 8 to 18 years with high myopia were studied. The spherical equivalent of refractive error (SER) and AL were measured, and SS-OCT images were recorded at baseline, and at 1, 3, 6, and 12 months after beginning RLRL therapy. Results: Twelve months of RLRL therapy led to an average reduction in myopic SER by 0.29 D (95% CI, 0.10 to 0.49 D; P < 0.05) and stabilization of AL, with a mean change of -0.03 mm (95% CI, -0.09 to 0.04 mm; P = 1.00). AL shortening >0.05 mm was observed in 53.8% of eyes. The average increase in the macular choroidal thickness was 26 µm (95% CI, 20 to 32 µm; P < 0.05), and an apparent change in posterior scleral curvature was observed in 5/26 (19.2%) eyes. One participant discontinued the RLRL therapy on day 2 because of photophobia. None of the other participants reported persistent photophobia or afterimage throughout the study, but one had 2 line reduction in BCVA without any OCT structural change. Conclusions: RLRL therapy was associated with AL stabilization in highly myopic eyes. Although apparent scleral curvature change was observed, it was a post hoc analysis in a small number of eyes and its association with choroidal thickness and the shortening of the AL needs further investigation.