AIM: To use optical coherence tomography angiography(OCTA)in measuring the macular vascular density, foveal avascular zone(FAZ)area and the macular retinal thickness in patients with retinal vein occlusion(RVO).METHODS: Totally 30 patients(30 eyes)with unilateral RVO were enrolled. Fifteen patients with central retinal vein occlusion(CRVO)and 15 patients with branch retinal vein occlusion(BRVO), OCTA was performed on both eyes. Macular vascular density in the 3mm×3mm range, FAZ area, foveal thickness and best-corrected visual acuity(BCVA)were measured. The changes of vascular density, FAZ area, foveal thickness and its correlation with BCVA were compared between the eyes and the fellow eyes.RESULTS: In eyes with CRVO the overall vascular density measured in the entire scan was lower compared to fellow eyes in both the superficial [SVN:(43.07±4.95)% vs (50.09±2.86)%; P<0.01)]and [DVN:(45.89±4.12)% vs(53.29±2.62)%; P<0.01]. And a negative correlation was found between the visual acuity and the overall density in superficial(rs= -0.6, P<0.05)and deep(rs= -0.5, P<0.05)networks. In eyes with BRVO the overall vascular density measured in the entire scan was lower compared to fellow eyes in both the superficial [(45.62±3.04)% vs(52.10±2.98)%; P<0.01] and deep [(49.21±3.80%)vs(55.52±3.33)%; P<0.01] networks. And a negative correlation was found between the visual acuity and the overall density in superficial(rs= -0.5, P<0.05)and deep(rs= -0.5, P<0.05)networks. In both networks, the density was lower in the affected BRVO sector compared to the unaffected sector in the same eye and in the fellow eye(P<0.01). And the vascular density in the affected BRVO sector correlated negatively with visual acuity in the deep network(rs= -0.6, P=0.01). In the deep network, the density was lower in the unaffected sector of the BRVO eye compared with the corresponding sector in the fellow eye [(56.86±1.95)% vs(58.15±2.24)%; P=0.02]. The mean FAZ area in CRVO and BRVO eyes was significantly lower at the superficial network when compared to the fellow eyes \ and correlated positively with visual acuity(CRVO: rs=0.6, P=0.01; BRVO: rs=0.5, P=0.01). The mean foveal thickness in CRVO and BRVO eyes was significantly thicker when compared to the fellow eyes \ and correlated positively with visual acuity(CRVO: rs=0.9, P=0.01; BRVO: rs=0.6, P=0.01).CONCLUSION: Quantitative OCTA can be used as an effective tool for measuring blood flow in macular areas and FAZ area of RVO patients.