ObjectiveTo observe the changes of macular microvascular structure in eyes with macular edema secondary to branch retinal vein occlusion (BRVO-ME) after intravitreal injection of conbercept and analyze its relationship with visual function and central retinal thickness (CRT).MethodsA prospective clinical study. From July 2018 to June 2019, 21 eyes of 21 patients with unilateral temporal BRVO-ME diagnosed in the Department of Ophthalmology of Peking Union Medical College Hospital were included in the study. Among them, there were 14 eyes of 14 males and 7 eyes of 7 females; the average age was 58.0±8.3 years. There were 13 eyes and 8 eyes with occlusion of the superior temporal and inferior temporal branches of the retinal vein, respectively. The affected area was defined as the side of the venous obstruction. All the affected eyes underwent best-corrected visual acuity (BCVA) and optical coherence tomography angiography (OCTA) examination. The BCVA was tested using the international standard logarithmic visual acuity chart, which was converted into the logarithmic minimum angle of resolution (logMAR) visual acuity during statistical analysis. All the eyes were treated with intravitreal injection of conbercept once a month for 3 months, and then treated as needed. A 3 mm × 3 mm scan centered on fovea was obtained and the vascular density of superficial capillary plexus (SCP) and deep capillary plexus (DCP), fovea avascular zone (FAZ) area, perimeter of FAZ (PERIM), acircularity index (AI), foveal vascular density in a 300 μm wide region around FAZ (FD-300) and central retinal thickness (CRT) were measured. The follow-up time after treatment was 6 months. The vascular density and FAZ parameters were compared before and after treatment by paired t test. The correlations of BCVA, CRT and vascular density, FAZ area and the other parameters at 6 months after treatment were analyzed by linear regression analysis. ResultsBefore treatment, the logMAR BCVA of the eyes was 0.506±0.159, and the CRT was 375.4±81.3 μm; 6 months after treatment, the logMAR BCVA of the eyes was 0.294±0.097, and the CRT was 266.3±46.7 μm. There was a statistically significant difference of logMAR BCVA and CRT between the eyes before and after treatment (t=8.503, 9.843; P＜0.05). There was no statistically significant difference in the overall vascular density of SCP and DCP before and 6 months after treatment (t=－0.091, －0.320; P＞0.05). The foveal vascular density decreased, and the difference was statistically significant (t=8.801, 3.936; P＜0.05). The vascular density of DCP of the affected area increased, and the difference was statistically significant (t=－2.198, P＜0.05). Compared with those before treatment, the FAZ area and PERIM of the affected eyes had an increasing trend, while AI and FD-300 had a decreasing trend, and the differences were statistically significant (t=－18.071, －12.835, 2.555, 8.610; P＜0.05). The linear regression analysis showed that BCVA and FAZ area 6 months after treatment have significant correlation (t=2.532, P=0.024). ConclusionCRT decreased and BCVA increased after intravitreal injection of conbercept in BRVO-ME eyes. After treatment, the foveal vascular density of SCP and DCP decreased while the vascular density of DCP of the affected area increased. The FAZ increased and the PERIM and AI decreased during follow-up. The BCVA was significantly correlated with the FAZ area 6 months after treatment.