Effect of nasal and temporal scanning tilt on whole and local macular vessel density measurement using OCTA

To evaluate the effects of scanning tilt on the macular vessel density (VD) measurements in healthy subjects using optical coherence tomography angiography (OCTA).

OCTA imaging was performed on healthy subjects to acquire nasal and temporal oblique scans. Quantitative analyses included as follows: (1) VD in whole-image, annular, and quadrant regions of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) layer; (2) Foveal avascular zone (FAZ) parameters (area, perimeter, circularity index) in the SCP.

Twenty-eight eyes of 28 healthy participants were included. Nasal inclination significantly affected VD measurement in the SCP temporal quadrant, DCP nasal/temporal/inferior quadrants, and all CC regions (all P < 0.05). Temporal tilt influenced VD measurements in all regions except the SCP superior and temporal quadrants (all P < 0.05). While FAZ area and perimeter remained unaffected by tilt, temporal tilt significantly reduced FAZ circularity (P = 0.022).

The tilt of the OCTA scan has different effects on the VD measurements of the whole, annular, and quadrant regions of macular layers and the FAZ circularity index.