Real-Time High-Resolution OCT for Imaging Retinal and Choroidal Blood Flow

Purpose: To evaluate the feasibility of visualizing intravascular moving particles within retinal and choroidal vessels using real-time high-resolution optical coherence tomography (High-Res OCT), a prototype device offering 3-µm axial resolution. Methods: In this cross-sectional study, 20 healthy eyes were imaged using both High-Res OCT and the standard SPECTRALIS HRA+OCT. A dedicated in-built research tool enabled ART-1 B-scan movie acquisition with real-time eye-tracking. Two masked graders qualitatively assessed visibility and direction of intravascular moving particles, and intergrader agreement was evaluated using Gwet's agreement coefficient 1 (AC1). Four additional patients with retinal vascular disorders (retinal artery occlusion, diabetic retinopathy, hypertensive retinopathy, and neovascular age-related macular degeneration) were imaged with High-Res OCT to explore illustrative clinical applications. Results: High-Res OCT demonstrated superior visualization of intravascular moving particles compared with standard OCT in both arteries (80% vs. 50%; P = 0.01) and veins (90% vs. 60%; P = 0.03). Intergrader agreement was high for High-Res OCT (AC1, 0.82-0.89) and moderate-to-substantial for standard OCT (AC1, 0.53-0.71). Flow direction assessment did not differ significantly between devices, although correct identification was numerically higher with High-Res OCT. In pathological eyes, real-time High-Res OCT enabled dynamic visualization of pulsatile and disturbed flow patterns and distinct intravascular motion across multiple vascular conditions. Conclusions: Real-time High-Res OCT enables direct, non-invasive visualization of intravascular moving particles within retinal and choroidal vessels and improves flow detectability compared with conventional OCT. This technique offers novel qualitative insights into ocular vascular dynamics and may guide future quantitative and translational applications.