compare the results of vitrectomy with or without arteriovenous (AV) crossing sheathotomy for macular edema associated with branch retinal vein occlusion (BRV O). Interventional case series. A retrospective study of 36 eyes with BRVO-asso ciated macular edema. Twenty eyes underwent AV sheathotomy (AS group), and 16 ey es underwent posterior vitreous detachment (PVD group). Best-corrected visual a cuity (BCVA), fluorescein angiography (FA), and optical coherence tomography to determine foveal thickness were conducted preoperatively and at 12 months postop eratively. The mean postoperative BCVAs were significantly better in both the AS and the PVD group (P =. 008 and P=. 001, respectively). Foveal thickness decrea sed significantly 1 month after surgery in both groups (P=. 002 and P=. 007) and continued to decrease up to 12 months. The postoperative mean BCVA and improvem ent of BCVA and foveal thickness were not significantly different for the two gr oups at any postoperative period. Postoperative FA showed reperfusion of the occ luded vein in 10 eyes in the AS group and 2 eyes in the PVD group, and formation of shunt vessels at the AV crossing site or around the macular region in all of the other eyes of both groups. Both AV sheathotomy and simple PVD significantly reduced macular edema associated with BRVO. However, there was no significant d ifference in the improvement of macular function following either procedure. Pos toperative improvement of retinal circulation by either reperfusion of the occlu ded vein or collateral vessel formation was found. This accounted for functional and morphologic improvements. compare the results of vitrectomy with or without arteriovenous (AV) crossing sheathotomy for macular edema associated with branch retinal vein occlusion (BRV O). Interventional case series. A retrospective study of 36 eyes with BRVO-asso ciated macular edema. Twenty eyes underwent AV Best-corrected visual a cuity (BCVA), fluorescein angiography (FA), and optical coherence tomography to determine foveal thickness were conducted preoperatively and at 12 months postop eratively. The mean postoperative BCVAs were significantly better in both the AS and the PVD group (P =. 008 and P =. 001, respectively). Foveal thickness decrea sed significantly 1 month after surgery in both groups (P =. 002 and P =. 007) and continued to decrease up to 12 months. The postoperative mean BCVA and improve ent ent of BCVA and foveal thickness were not significantly different for the two gr oups at any postoperative period. Po stoperative FA showed reperfusion of the occluded vein in 10 eyes in the AS group and 2 eyes in the PVD group, and formation of shunt vessels at the AV crossing site or around the macular region in all of the other eyes of both groups. Both AV sheathotomy and simple PVD Signific reduced macular edema associated with BRVO. However, there was no significant d ifference in the improvement of macular function following either procedure. Pos toperative improvement of retinal circulation by either reperfusion of the occlu ded vein or collateral vessel formation was found. This accounted for functional and morphologic improvements.