Purpose The aim was to assess radial peripapillary capillary (RPC) and macular vascular density in eyes with primary open angle glaucoma (POAG). Patients and methods This observational cross-sectional study included 60 eyes of normal person and 67 eyes with POAG. Glaucomatous eyes were subdivided into three groups according to visual field findings; mild, moderate, and severe glaucoma (14, 27, and 26 eyes, respectively). Both RPC and macular vascular density were measured using optical coherence tomography angiography (OCTA). Visual field mean deviation was analyzed. Retinal nerve fiber layer (NFL) thickness and ganglion cell complex thickness were determined using OCT in all eyes. Results Peripapillary retinal NFL (thickness and ganglion cell complex thickness were significantly different between glaucomatous and normal eyes (P<0.001). In eyes with POAG, RPC vascular density was significantly less than normal ones (P<0.001) and was correlated with glaucoma severity (P=0.02). A significant correlation was found between RPC vascular density and visual field mean deviation and NFL thickness. Macular vascular density was significantly less in glaucomatous eyes (P<0.001) with significant correlation with the degree of glaucoma severity (P=0.01). Conclusion OCTA has the ability of visualization and quantification of RPC and macula vessel density and may be useful in measuring retinal ganglion cell damage in open angle glaucoma.