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

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.