ObjectiveTo observe the macular vascular density and the area of foveal avascular zone (FAZ) in the follow eyes of monocular retinal vein occlusion (RVO) patients.MethodsRetrospective case-control study. From May to November 2018, 78 follow eyes of 78 monocular RVO patients who were clinically diagnosed in Changsha Aier Eye Hospital were included in the study. Among them, 44 were male and 34 were female. The average age was 53.17±10.12 years. There were 42 patients with central retinal vein occlusion (CRVO group) and 36 patients with branch retinal vein occlusion (BRVO group). Forty-two eyes of 33 gender and age matched healthy volunteers were selected as the control group. Among them, 17 were male (22 eyes) and 16 were female (20 eyes), with the mean age of 53.48±10.84 years. OCT angiography was performed on all eyes in CRVO group, BRVO group and control group. The scanning region in the macular area was 6 mm×6 mm. Macular vascular density and FAZ area in the superficial and deep retinal capillary plexi were measured.ResultsThe mean overall vascular density measured in the entire scan was lower in the CRVO group (t=－4.26, －4.93) and BRVO group (t=－4.79, －4.74) compared with the control group in both the superficial and deep capillary plexus (P＜0.05). The reduce degree of vascular density in the deep capillary plexus (CRVO group:5.51%, BRVO group:4.58%) was higher than that in the superficial plexus (CRVO group:4.13%, BRVO group:3.50%). In the CRVO group, the FAZ area decreased compared with the control group (t=－3.43, P＜0.05). There was no statistically significant difference in the area of FAZ between the BRVO group and the control group (t=－0.10, P＞0.05).ConclusionsThe macular vascular density in the follow eyes of monocular RVO patients is lower than that of normal healthy eyes. The reduce degree of vascular density in the deep capillary plexus is higher than that in the superficial plexus. Compared with normal healthy eyes, the FAZ area in the follow eyes of monocular CRVO patients decreased, while it did not change significantly in the follow eyes of monocular BRVO patients.