Purpose: To document the anatomic and functional improvement of six patients withbranch retinal vein occlusion (BRVO) following successful arteriovenous adventitialsheathotomy (AAS).Methods: Retrospective study of 6 patients (6 eyes) with BRVO treated with AAS. Allpatients were not eligible for laser photocoagulation and had both macular edema andintraretinal hemorrhage. The visual acuity was in the range of 0.4 to 0.02. All patientsunderwent pars plana vitrectomy and AAS. The clinical improvement was determined byfundus photograph, fluorescein angiography (FAG), optical coherence tomography(OCT) and multifocal electroretinography (ERG). All patients were followedpostoperatively for an average of 20 months ranging from 12 to 24 months.Results: Sheathotomy and decompression of the arteriole/venule (A/V) crossing wereachieved in all 6 patients. 5 patients have improved their best-corrected visual acuity 4lines or more. The best one could reach to 1.0. One month after the operation, fundusphotograph and FAG demonstrated the resolution of intraretinal hemorrhage, reduction ofnon-perfusion area and apparent resolution of retinal venous dilation and tortuosity. OCTconfirmed remarkable reduction of retinal thickness. The microcysts at the foveadiminished. Multifocal ERG showed the recovery of the central peak at the macular andthe peripheral response density. However, capillary nonperfusion area andmicroaneurysm were found out by FAG in four patients at the points distal to thesheathotomy three months after the operation.Conclusions: Anatomic and functional improvement of retina can be achieved in patientswith BRV0 through AAS. However, the capillary nonperfusion and microaneurysm mayfollow this surgical procedure in some cases that need further treatment with laserphotocoagulation. The better visual improvement may be expected in the patients withearlier surgical intervention.