Longitudinal changes in choroidal structures among children with low to moderate myopia under orthokeratology treatment.

Purpose: To explore the longitudinal changes in choroidal features in myopic children with low to moderate myopia under orthokeratology (ortho-k) treatment.

Methods: Children (n = 80) aged 8-12 years with spherical equivalent refraction of -1.00 to -6.00D were randomly assigned to the control (single vision spectacles) (n = 40) and ortho-k (n = 40) groups. OCT images were collected at the baseline, 1-, 6-, 12-, 18-, and 24-month visits. Choroidal structure parameters, including choroidal total area (TA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI) were calculated. Axial length (AL) was measured as the primary indicator for myopic progression. The analysis followed the intention-to-treat criteria.

Results: Compared to the control, ortho-k significantly improved the choroidal structures in choroidal TA and LA at all follow-up points (all P < 0.05). Choroidal LA was the primary contributor to TA changes (85.8 %[control], 91.4 %[ortho-k]), with the most significant improvement within the first 6 months. While, the changes in SA and CVI over time were not significantly different between the two groups (all P > 0.05). Correlation matrices identified several noteworthy correlations between AL change and choroidal structure features. Further analysis showed a significant interaction effect between baseline choroidal LA and intervention type on subsequent AL change (P for interaction = 0.005), suggesting that ortho-k might be more effective in children with larger baseline choroidal LA.

Conclusions: This 2-year prospective study demonstrated that ortho-k can improve the choroidal structures, primarily manifested in choroidal LA, although this positive effect diminishes over time. Myopic children with larger baseline choroidal LA might benefit more from ortho-k.