Purpose: To measure low perfusion area (LPA) and focal perfusion loss (FPL) in the macula using OCT angiography (OCTA) for glaucoma. DesignProspective, cross-sectional “case-control” comparison study. Methods: A total of 60 patients with primary open-angle glaucoma (POAG) and 37 normal participants were analyzed. AngioVue 6 × 6-mm high-definition (400 × 400 transverse pixels) macular OCTA scans were performed on one eye of each participant. Flow signal was calculated using the split-spectrum amplitude-decorrelation angiography algorithm. En face ganglion cell layer plexus (GCLP) and superficial vascular complex (SVC) images were generated. Using custom software, vessel density (VD) maps were obtained by computing the fraction of area occupied by flow pixels after low-pass filtering by local averaging 41 × 41 pixels. LPA was defined by local VD below 0.5 percentile over a contiguous area above 98.5 percentile of the normal reference population. The FPL was the percent VD loss (relative to normal mean) integrated over the LPA. Results: Among patients with POAG, 30 had perimetric and 30 had pre-perimetric glaucoma. The LPAGCLP-VD was 0.16±0.38 mm2 in normal and 5.78±6.30 mm2 in glaucoma subjects (P<0.001). The FPLGCLP-VD was 0.20%±0.47% in normal and 7.52%±8.84% in glaucoma subjects (P<0.001). The perimetric glaucoma diagnostic accuracy, measured by the area under the receiver operating curve, was 0.993 for LPAGCLP-VD and 0.990 for FPLGCLP-VD. The sensitivities were 96.7% and 93.3% at 95% specificity, respectively. The LPAGCLP-VD and FPLGCLP-VD had good repeatability (0.957 and 0.952 by intraclass correlation coefficient). Diagnostic accuracy was better than GCLP VD (AROC 0.950, sensitivity 83.3%) and OCT ganglion cell complex (GCC) thickness (AROC 0.927, sensitivity 80.0%), GCC focal loss volume (AROC 0.957, sensitivity 80.0%). The LPAGCLP-VD and FPLGCLP-VD correlated well with central VF mean deviations (Pearson's r=-0.716 and -0.705 respectively, both P<0.001). Conclusion: Assessment of macular focal perfusion loss using OCTA is useful in evaluating glaucomatous damage.