Angiotensin I-converting enzyme D/D genotype [Odds Ratio (OR) = 3.83, 95% Confidence Interval (CI) = 1.10-13.37, p = 0.035, diabetes mellitus (OR = 2.90, 95% CI = 1.19-7.09, p = 0.019) and hypertension (OR = 4.48, 95% CI 1.86-10.83, p = 0.001) were found to be the independent predictive factors for RVO in multivariate logistic regression analysis. The gene discussed is ACE; the disease is diabetes mellitus.