We examined the prevalence of retinal microvascular signs among carriers of the 3 main APOE alleles (ε2, ε3, and ε4) and 6 genotypes (ε2/ε2, ε2/ε3, ε2/ε4, ε3/ε3, ε3/ε4, and ε4/ε4); however, for ease of interpretation, only the results of the allele analyses are given. We defined ε2 allele carriers to include genotypes ε2/ε2, ε2/ε3, and ε2/ε4; and ε4 allele carriers to include genotypes ε3/ε4 and ε4/ε4. Because allele frequencies are different in white and black individuals, we performed analyses separately. We tested whether the distribution of APOE alleles was in Hardy-Weinberg equilibrium using χ² tests comparing observed with expected proportions. As hypertension is strongly associated with retinal microvascular signs, we performed subgroup analyses in persons with and without hypertension. Analysis of covariance was used to obtain adjusted mean retinal vessel diameters. We calculated odds ratios (ORs) and confidence intervals (CIs) for focal retinal microvascular signs by APOE allele frequency using the ancestral ε3/ε3 genotype as the reference group in logistic regression models. We constructed 2 nested models: (1) the adjusted model was adjusted for age (defined as a continuous variable in years), sex, and ARIC field center, and (2) the multivariate-adjusted model was adjusted for age (years), sex, ARIC field center, diabetes, fasting glucose, systolic blood pressure, current smoking (yes/no), body mass index, total serum cholesterol, total serum triglycerides, and hypertension status. All P values are 2 sided, and SAS version 8.2 (SAS Institute Inc, Cary, NC) was used for all analyses.