Associations of Retinal Curvature With Choroidal Thickness and OCTA-Derived Choroidal Flow-Density Metric in High Myopia: A Two-Center OCTA Study of Interocular Asymmetry.

Purpose: The purpose of this study was to investigate the relationship between RC and choroidal structural and perfusion-density metrics in high myopia, and to determine whether interocular asymmetry is more closely associated with structural differences or optical coherence tomography angiography (OCTA)-derived perfusion differences. Methods: In this two-center cross-sectional study, participants with and without high myopia underwent OCTA imaging. RC (10-2 mm-2), choroidal thickness (CT, µm), and OCTA-derived choroidal flow-density metric (CF, %) were quantified within six concentric macular rings centered on the fovea. Eye-level associations between the RC and choroidal metrics were evaluated using generalized estimating equation models adjusting for age, sex, axial length (AL), and imaging center. Interocular (within-subject) asymmetry was primarily assessed using participant-level interocular difference analyses, with linear regression models evaluating associations between ΔRC and corresponding differences in ΔCT and ΔCF after adjustment for interocular AL difference and imaging center. Additional Spearman correlation analyses were performed as nonparametric robustness checks. Sensitivity analyses and measurement repeatability assessments were performed to evaluate robustness. Results: At the eye level, a steeper RC was significantly associated with reduced choroidal thickness across multiple macular rings, with the strongest association observed in the parafoveal region (ring 3), followed by the central macula (ring 1), and weaker associations toward the peripheral retina (ring 6). These associations remained significant after multivariable adjustment and correction for multiple comparisons. Associations between RC and CF density were weaker and more region-dependent: significant RC main effects were observed in selected rings (notably ring 3 and ring 6) in the eye-level analysis, whereas these associations were not consistently supported in the interocular analysis after multivariable adjustment and correction for multiple comparisons. Interocular analyses demonstrated that ΔRC was strongly and consistently associated with ΔCT, again with the largest effect observed in ring 3. These findings were robust across sensitivity analyses for CT, whereas the corresponding results for CF density were less consistent across analytical approaches. RC and CT measurements exhibited excellent repeatability, with intraclass correlation coefficients (ICCs) exceeding 0.98. Conclusions: RC was consistently associated with CT at both the eye level and in interocular comparisons, whereas associations with the OCTA-derived CF density metric were weaker, region-dependent, and not consistently supported in interocular analyses. These findings suggest that interocular asymmetry in high myopia is primarily associated with structural differences, with less consistent involvement of the OCTA-derived flow-density metric assessed in this study. Translational Relevance: OCTA-based RC assessment may provide a clinically accessible framework for regional evaluation of posterior pole structure in high myopia; however, further validation in longitudinal and multi-platform studies is required.