Effective interscan time for enhanced in vivo choriocapillaris imaging with OCT angiography

Despite advancements in optical coherence tomography angiography (OCTA), in vivo imaging of the choriocapillaris (CC) remains challenging due to its dense microvascular structure and low reflectivity. While previous studies have explored various scanning protocols to enhance CC visualization, most approaches rely on oversampling, beam size adjustments, large numbers of repetitive B-scans (BM), and volume registration. However, interscan time-a critical parameter that influences flow contrast and vascular detail-has been largely overlooked. In this Letter, we introduce interscan time as a novel, to the best of our knowledge, CC imaging parameter and propose an optimized OCTA protocol by leveraging a 1.6 MHz FDML swept-source laser and step-bidirectional scanning method to investigate its impact across beam sizes and BM-scans. Our findings reveal that shorter interscan time significantly improves CC visualization by enhancing vessel contrast and preserving microvascular details, enabling better clinical assessment of retinal diseases such as age-related macular degeneration and diabetic retinopathy.