**3.2 Optical coherence tomography angiography features of the peripapillary region in glaucoma**

Compared to healthy eyes, glaucomatous eyes show significantly lower peripapillary VD and blood flow index. A systematic review conducted by Bekkers et al. determined that the peripapillary microvasculature zone was the most discriminative region to aid glaucoma diagnosis as it provided an area under receiver operator characteristic curve AUROC of 0.8. [32]. Further gains in AUROC were obtained when model parameters were constricted to the superficial capillary plexus within the peripapillary region (AUROC =0.87).

Later work by De Jesus et al. confirmed that the superficial layer of the peripapillary region was the most useful OCTA metric to discern a glaucoma diagnosis, as damage was most prominent in this zone of the eye when compared to healthy controls [31]. Thus, analyzing the peripapillary region is a powerful application of OCTA as it provides the highest discriminant power to differentiate between healthy and glaucomatous eyes.
