Purpose: To identify indices of visual improvement after conservative treatment for branch retinal vein occlusion (BRVO) with macular edema. Methods: We retrospectively reviewed the charts of 33 eyes of 33 patients with BRVO with macular edema. Inclusion criteria were 1) onset within 4 months, 2) decimal visual acuity of 0.05 to 0.5, and 3) minimum central subfield thickness (CST) of 250 μm. After 3 months of treatment with oral aspirin and kallidinogenase, the patients were divided into two groups: those with logarithmic minimum angle of resolution (logMAR) visual improvement of 0.3 or more (14 eyes) and less than 0.3 (19 eyes). We then compared systemic and ocular findings in the groups. Results: The groups differed significantly in logMAR improvement after 1 month (p<0.01) and in CST change after 1 month (p<0.05). Multiple logistic regression analysis showed that CST change after 1 month was a significant index of visual improvement (p<0.05). The cutoff value for visual improvement was -30 μm (sensitivity: 78.6, specificity: 68.4, positive predictive value: 64.7, negative predictive value: 81.3). Conclusion: A decrease in CST of more than 30 μm 1 month after conservative treatment indicates that visual acuity is likely to be improved after 3 months.