Geometric and concavity characteristics as diagnostic markers for differentiating nAMD-related MNV from pachychoroid neovascularisation.

PURPOSE: To investigate morphometric differences in macular neovascularisation (MNV) outer contours between neovascular age-related macular degeneration (nAMD) and pachychoroid neovasculopathy (PNV) using quantitative optical coherence tomography angiography (OCTA) analysis.

METHODS

This retrospective cross-sectional study enrolled treatment-naïve patients with newly diagnosed MNV, classified into nAMD and PNV groups. The nAMD group was further subdivided into Type 1 MNV, Type 2 MNV, and polypoidal choroidal vasculopathy (PCV). A semi-automated pipeline integrating FIJI-based contour extraction and custom Python algorithms quantitatively analysed four MNV morphometric domains: geometric parameters, shape descriptors, concavity features, and orientation.

RESULTS

Eighty-nine eyes (89 patients) were included (64 nAMD, 25 PNV). PNV patients were significantly younger (P < 0.001) with better visual acuity (P = 0.026), longer symptom duration (P < 0.001), and greater subfoveal choroidal thickness (P < 0.001). nAMD-related MNV exhibited significantly larger geometric dimensions (all P < 0.05) and deeper marginal indentations (maximum: 0.41 ± 0.33 vs. 0.21 ± 0.14 mm, P = 0.009; mean: 0.17 ± 0.12 vs. 0.10 ± 0.06 mm, P = 0.002) compared to PNV. These differences were more pronounced between PCV and PNV (all P < 0.001). ROC analysis demonstrated moderate discriminative performance for nAMD versus PNV (AUC = 0.711 and 0.723) and good performance for PCV versus PNV (AUC = 0.778 and 0.840) using equivalent diameter and mean concavity depth.

CONCLUSION

Outer contour morphometry effectively differentiates MNV aetiologies, with nAMD (particularly PCV) showing larger, more lobulated patterns than PNV's compact configurations, likely reflecting distinct pathophysiological mechanisms.