Adaptive scan intervals in ultrawide-field OCT angiography achieved by a bidirectional interleaved approach

Conventional unidirectional scanning rigidly couples the scan interval (t _inter) to sampling density in ultra-wide field optical coherence tomography angiography (UWF-OCTA), which impedes optimal imaging of different blood flow velocities. In this study, we implement an adaptive bidirectional interleaved scanning pattern for UWF-OCTA that enables the adjustment of t _inter while keeping the scan area, sampling density, and total acquisition time constant or optimally tuned. We implemented this pattern on our high-speed (800 kHz/1 MHz) swept-source UWF-OCTA prototypes and assessed image quality across several use cases, including pediatric patients, non-human primates, and rodents. This protocol successfully captured detailed UWF-OCTA images with well-defined microvascular patterns. We observed that, while keeping sampling density and total scan acquisition time constant, a longer t _inter enhances sensitivity to slower retinal blood flow, whereas a shorter t _inter yields more robust, motion-resistant images with clearer choroidal vasculature, as supported by quantitative contrast-to-noise ratio analysis. These findings illustrate that the optimal t _inter is dependent on the specific application and pathology, and validate the adaptive scanning pattern as a useful approach for tailoring UWF-OCTA to diverse clinical needs.