Large-caliber choroidal arteriovenous shunt in macular neovascularization: A brief report of a novel morphological finding

BACKGROUND: Macular neovascularization (MNV) etiology is multifactorial, but direct evidence linking it to abnormalities of large choroidal vessels is lacking. This study aimed to investigate the potential role of abnormal spatial relationships between large choroidal arteries and veins in the pathogenesis of MNV, particularly in eyes with large veins traversing the macular area. METHODS: This retrospective study analyzed 45 eyes from 45 patients (26 with chronic central serous chorioretinopathy [CSC] and 19 with pathologic myopia [PM]) exhibiting large macular veins without a normal venous watershed. All patients underwent simultaneous fundus fluorescein angiography and indocyanine green angiography (ICGA). Arterial and venous phase ICGA images were selected, nonlinearly registered, and superimposed using Fiji/ImageJ software to visualize spatial arteriovenous relationships. RESULTS: Spatial relationships between large choroidal arteries and veins were clearly discernible in significantly more PM eyes (18/19, 94.7 %) than CSC eyes (6/26, 23.1 %) (P < 0.0001). Among eyes with clear visualization, various spatial configurations were observed, including crossing, twisting, and independence. Crucially, in two distinct MNV cases-one secondary to chronic CSC (thick choroid) and one secondary to PM (thin choroid)-direct, large-caliber arteriovenous shunts were identified precisely at the MNV site using this imaging approach. CONCLUSION: This study provides direct ICGA evidence that abnormal shunts between large choroidal arteries and veins represent a novel, underrecognized etiology for MNV formation. This anatomical anomaly may act as an upstream hemodynamic driver across different choroidal backgrounds (thick or thin), potentially altering local hemodynamics and promoting neovascularization. Investigating these underlying arteriovenous relationships could improve CNV risk stratification and inform future treatment strategies.