Longitudinal changes in choroidal thickness in high myopia: Correlation with maculopathy progression and visual outcomes

Abstract Purpose To evaluate longitudinal changes in choroidal thickness (CT) in highly myopic eyes and their correlation with myopic maculopathy progression and visual outcomes. Methods Retrospective cohort study on 1228 eyes from 781 highly myopic patients with a minimum 5‐year follow‐up (mean 11.5 ± 3.1 years). Myopic atrophic maculopathy (MAM) was graded according to ATN classification. Subfoveal CT was measured using spectral‐domain OCT with enhanced depth imaging. Staphyloma classification followed Curtin's system. Results Mean subfoveal CT at baseline was 54.3 ± 32.7 μm, with decreasing values by MAM category: tessellated fundus (172.5 ± 42.6 μm), diffuse chorioretinal atrophy (63.7 ± 27.3 μm), patchy atrophy (39.2 ± 18.3 μm) and macular atrophy (7.2 ± 11.3 μm, often unmeasurable). Different thinning rates were observed: diffuse atrophy (3.1 ± 0.9 μm/year), patchy atrophy (2.1 ± 0.8 μm/year), macular atrophy (1.3 ± 0.7 μm/year) and tessellated fundus (1.2 ± 0.6 μm/year). Lowest CT values were observed in eyes with type IX staphyloma (22.4 ± 12.1 μm). Axial length ≥ 29 mm was associated with lower CT (32.4 ± 18.9 vs. 78.6 ± 36.2 μm, p < 0.001). Baseline CT <40 μm independently predicted macular atrophy development (OR 3.84, p < 0.001) and visual decline (OR 2.76, p < 0.001). Eyes with dome‐shaped macula showed thicker CT at dome peak compared with peridome edges (62.3 ± 34.2 vs. 48.4 ± 22.7 μm, p = 0.002). Eyes developing myopic macular neovascularization (mMNV) had lower baseline CT (32.7 ± 17.8 vs. 58.6 ± 33.1 μm, p < 0.001). Conclusions The fastest choroidal thinning occurred in eyes with diffuse chorioretinal atrophy, while eyes with severely reduced baseline CT had a higher risk for macular atrophy development and visual impairment. Different staphyloma types showed variable CT patterns.