Fig. 1
Graphical representation for PPCV reconstruction using DB OCTA. a Representative image obtained from a DB OCTA examination. Each peripapillary area was subdivided into four regions of interest—the temporal superior quadrant, temporal inferior quadrant, nasal superior quadrant, and nasal inferior quadrant. The scan area was 10° × 0.5° (3 mm × 0.15 mm), and the scan angle was 45° for all subjects. The scan was moved manually at 1/2 PD of the edge of the optic disk. b High-quality B-scan OCTA images acquired using the dart-volume scan mode of DB OCTA for retinal capillary flow volume reconstruction. b1 All 25 high-quality B-scan OCTA images from one area of interest with an interscan distance of 6-μm in nominal spacing were used for retinal blood flow volume reconstruction. Each B-scan OCTA image contained all retinal blood vessels within the same cross-section, including the superficial (b2), intermediate (b3), and deep (b4) vascular plexus. c A high-quality B-scan OCTA image loaded into ImageJ software to analyze the retinal cross-sectional capillary flow area. c1 The signal graphics in yellow represent blood flow detected by DB OCTA. c2 ImageJ was used to adjust the brightness and threshold of the images and depict the blood flow signals that fell within the threshold setting as red. The “polygon selections” tool was used to define the region of retinal blood flow (the area within the yellow lines). c3 The area of the retinal blood flow signal was determined by selecting “analyze > measure” command in ImageJ. Blood vessel areas (the areas confirmed by the expert ophthalmologist) were excluded to calculate the retinal capillary flow area. PPCV, peripapillary capillary volume; DB OCTA, dense B-scan optical coherence tomography angiography