Retinal vein occlusion(RVO)is a common retinal vascular disease. Macular edema(ME)secondary to RVO is the main cause of visual impairment in patients. The mechanisms of ME secondary to RVO are intricate and have not yet been fully elucidated. Many cells and cytokines are involved in it, which disrupt the balance between fluid entry and exit in the retina. This review discusses the complex pathogenesis of ME associated with RVO and the mechanisms by which ME affects visual function.