Noninterchangeability of Vessel Density Measurements Across Next-Generation SS-OCTA Systems

Purpose: Comparing swept-source optical coherence tomography angiography (OCTA) vessel density in the superficial and deep capillary plexuses across leading OCTA systems. Methods: OCTAs were acquired from healthy participants using two OCTA systems (BMizar 400 kHz and Yalkaid 100 kHz, TowardPi, Beijing, China) with scan sizes of 3 × 3, 6 × 6, 12 × 12, and 15 × 15 mm2. The vessel density was quantified using the manufacturer's software. Results: Across 30 subjects comprising 60 eyes and a total of 225 OCTA scans, significant interdevice differences were observed at the Early Treatment Diabetic Retinopathy Study sector level in all eight scan size × plexus comparisons (three-way analysis of variance; P < 1.16 × 10e-4). The mean BMizar vessel density values for the superficial and deep plexuses were 43.4% ± 1.6% and 44.9% ± 1.5%, 44.7% ± 2.7% and 47.9% ± 1.1%, 44.2% ± 1.3% and 45.7% ± 1.1%, and 42.4 ± 1.6 % and 44.3 ± 1.3% for the 3 × 3, 6 × 6, 12 × 12, and 15 × 15 mm² scans; the Yalkaid values were lower. BMizar showed greater vessel density than Yalkaid, particularly in 3 × 3 mm² deep slab scans, with differences of approximately 5% to 10%. Across scans larger than 3 × 3 mm², BMizar showed greater central vessel density; the peripheral patterns varied, with reversals favoring Yalkaid and greater border effects in larger fields of view. Conclusions: Despite interdevice differences, both devices showed consistent OCTA acquisition. Translational Relevance: Device differences may affect clinical interpretation, longitudinal follow-up, and multicenter studies.