Purpose To study the detailed process of macular edema (ME) absorption after grid laser photocoagulation in patients with branch retinal vein occlusion (BRVO ). The influence of pretreatment serous retinal detachment (SRD) at the fovea on patient outcome was also evaluated. Design Retrospective, interventional, compa rative case series. Participants Thirty seven BRVO patients presenting with sev ere ME. Methods Patients were treated with grid laser photocoagulation with 6 mo nths of follow up examinations. Baseline and post treatment examinations inclu ded measurements of visual acuity (VA), fluorescein angiography, and detailed im aging of ME by optical coherence tomography (OCT). Macular thickness was defined as the distance from the inner retinal surface to the outer border of the senso ry retina (foveal retinal thickness) and also to the inner border of the retinal pigment epithelium including the SRD (total foveal elevation). Main outcome mea sures Post reatment macular thickness with OCT, VA converted to the logarithm of the minimum angle of resolution, and absorption of SRD, and correlations of mac ular thickness and VA both before and after treatment. Results Total foveal elev ation and VA were significantly improved at 1, 3, and 6 months after treatment. There was also a significant correlation between reduction of total foveal eleva tion and increase in VA. Fourteen eyes (37.8%) displayed SRD, as evidenced by O CT at the baseline. In eyes without SRD, foveal retinal thickness and VA had sig nificantly improved in a time dependent manner. However, although SRD itself was almost absorbed 6 months af ter treatment, the improvement of both VA and total foveal elevation in eyes wit h pretreatment SRD was not significant compared with baseline conditions. Both p ost treatment total foveal elevation and VA of eyes with SRD tended to be worse than eyes without SRD. Conclusion The presence of subfoveal SRD retards the abs orption of ME and recovery of VA after grid laser photocoagulation in patients w ith BRVO. Purpose To study the detailed process of macular edema (ME) absorption after grid laser photocoagulation in patients with branch retinal vein occlusion (BRVO). The influence of pretreatment serous retinal detachment (SRD) at the fovea on patient outcome was also evaluated. Design Retrospective Participants Thirty seven BRVO patients presenting with sev ere ME. Methods Patients were treated with grid laser photocoagulation with 6 mo nths of follow up examinations. Baseline and post examination examinations includations of visual acuity (VA) , fluorescein angiography, and detailed im aging of ME by optical coherence tomography (OCT). Macular thickness was defined as the distance from the inner retinal surface to the outer border of the senso ry retina (foveal retinal thickness) and also to the inner border of the retinal pigment epithelium including the SRD (total foveal elevation). Main outcome mea sures Post reatment macular thickness with OCT, VA converted to the logarithm of the minimum angle of resolution, and absorption of SRD, and correlations of mac ular thickness and VA both before and after treatment. Results Total foveal elevations and VA were significantly improved at 1, 3, and There was also a significant correlation between reduction of total foveal eleva tion and increase in VA. Fourteen eyes (37.8%) displayed SRD, as evidenced by O CT at the baseline. In eyes without SRD, foveal retinal thickness and VA had sig nificantly improved in a time dependent manner. However, although SRD itself was absorbed for 6 months af ter treatment, the improvement of both VA and total foveal elevation in eyes wit h pretreatment SRD was not significant compared with baseline conditions. Both p ost treatment total foveal elevation and VA of eyes with SRD tended to be worse than eyes without SRD. Conclusion The presence of subfoveal SRD retards the abs orption of ME and recovery of VA after gridlaser photocoagulation in patients w ith BRVO.