Circumferential mapping of human limbal vasculature and aqueous outflow pathways based on circular-scan anterior-segment optical coherence tomography

The corneal-scleral limbus contains crucial aqueous channels and veins that are critical for aqueous outflow and glaucoma research. Conventional imaging of the limbal vasculature often requires multi-quadrant scans with complex projection-angle correction or suffers from defocus artifacts due to the pronounced curvature of the sclera. In this study, we present a circular-scan anterior segment optical coherence tomography (CircAS-OCT) system for rapid, depth-resolved imaging of the full limbal vasculature. The system employs a pericentric optical design to minimize the beam incidence angle and reduce defocus across the curved ocular surface. It enables single-shot acquisition of circumferential OCT angiography (OCTA) in just 2.67 seconds with an annular pattern. To integrate other imaging contrasts of the aqueous outflow pathway, we introduce a registration framework that aligns and stitches OCTA images from other systems or scanning protocols onto the CircAS-OCT angiogram. Experimental results demonstrate precise vessel alignment across stitched images, along with multi-contrast mapping of the limbal vascular network, collector channel locations, and the area and biomechanics of trabecular meshwork. This platform provides a fast, robust, and extensible solution for anterior segment examination, with promising applications in glaucoma diagnostics and multimodal data integration.