Three-dimensional choroidal parameter differences in myopic anisometropia.

BACKGROUND: To quantitatively compare 3D choroidal parameters between fellow eyes in individuals with varying degrees of myopic anisometropia and evaluate their correlations with interocular differences in spherical equivalent (△SE) and axial length (△AL). METHODS: This retrospective cross-sectional study enrolled 102 participants (204 eyes) categorized into low (△SE < 2.0D), moderate (2.0D ≤ △SE < 3.0D), and high (△SE ≥ 3.0D) anisometropia groups. Choroidal parameters, including choroidal vascular volume (CVV), choroidal stroma volume (CSV), and 3D choroidal vascularity index (3D-CVI), were measured using swept-source optical coherence tomography (SS-OCT). Retinal vessel density (VD) and regional variations were analyzed. RESULTS: CVV and CSV were significantly lower in more myopic eyes across all groups (P < 0.05), with the greatest reductions observed in the high anisometropia group. Nasal regions exhibited the strongest correlations between △CVV/△CSV and △SE/△AL (coefficients up to 0.403, P < 0.001). No interocular differences in 3D-CVI were detected (P > 0.05). Retinal VD in the high anisometropia group was elevated in more myopic eyes (P < 0.05), suggesting compensatory microvascular changes. CONCLUSION: Three-dimensional choroidal metrics, particularly CVV and CSV, reflect myopic severity in anisometropia, with nasal choroid demonstrating heightened vulnerability to axial elongation. These findings highlight the potential of volumetric choroidal imaging for evaluating myopic structural changes and underscore the need for further longitudinal studies to elucidate causal mechanisms.