Increased choroidal stromal volume and altered choriocapillaris perfusion in neovascular AMD: An SS-OCTA association study.

PURPOSE: This study aimed to characterize quantitative choroidal metrics using swept-source optical coherence tomography angiography (SS-OCTA) across different stages associated with neovascular age-related macular degeneration (nAMD) and to identify structural and vascular associations.

METHODS

This cross-sectional study utilized SS-OCTA to quantify 6.0 × 6.0 mm² macular choriocapillaris flow density (CCFD), choroidal volume (CV), choroidal stromal volume (CSV), and choroidal vascular volume (CVV), choroidal stromal index (CSI), choroidal vascularity index (CVI) and CSV/CVV ratio. Comparisons were conducted between each pair of three groups: control eyes from healthy participants, fellow eyes and nAMD affected eyes from the same unilateral nAMD patients (fellow eyes representing a potential preclinical stage).

RESULTS

The study included 230 healthy control eyes from 116 age- and sex- matched participants, 110 unaffected fellow eyes and 104 nAMD affected eyes from 110 unilateral nAMD patients. Median CCFD was 45.33% (IQR: 4.82%) in controls, 46.50% (IQR: 2.35%) in fellow eyes and 44.41% (IQR: 6.68%) in nAMD eyes. Significant differences were found between controls and fellow eyes (Adjusted P = 0.003) and between fellow eyes and nAMD eyes (Adjusted P < 0.001). Median CSV was significantly higher in both unaffected fellow eyes (5.92 mm³, IQR: 2.67 mm³; Adjusted P = 0.006) and nAMD affected eyes (6.12 mm³, IQR: 2.71 mm³; Adjusted P = 0.012) compared to controls (5.49 mm³, IQR: 2.00 mm³). Other absolute volumes also showed significant intergroup differences: CV differed between control and fellow eyes (Adjusted P = 0.033), while CVV differed significantly only between affected and fellow eyes (Adjusted P = 0.015). In contrast, normalized compositional metrics (CSI, CVI and CSV/CVV ratio) showed no significant intergroup differences (all Adjusted P > 0.05). Multivariate regression analysis in nAMD affected eyes revealed an overall inverse correlation between CSV and CCFD, with this relationship reaching statistical significance the superior nasal, nasal, inferior temporal, inferior and inferior nasal quadrants (P < 0.05).

CONCLUSION

This cross-sectional study demonstrated an association between increased CSV and the presence of nAMD, including in high-risk fellow eyes. The inverse correlation between CSV and CCFD in nAMD eyes suggested a potential interplay between stromal expansion and microvascular compromise. These findings highlighted increased CSV as a candidate biomarker that warranted investigation in future longitudinal studies to determine its prognostic value for nAMD development.