Citation: Li X, Wong WL, Cheung CY, et al. Racial differences in retinal vessel geometric characteristics: a multiethnic study in healthy Asians. Invest Ophthalmol Vis Sci. PURPOSE. To investigate potential racial/ethnic differences in retinal vascular geometric parameters in a multiethnic Asian population (Chinese, Malay, and Indian) free of clinical diseases. METHODS. A series of retinal vascular parameters were measured from retinal photographs using a computer-assisted program following a

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... andardized protocol. Healthy participants were defined as nonsmokers, the absence of diabetes mellitus, uncontrolled hypertension, obesity, stroke, heart disease, glaucoma, and retinopathy. RESULTS . There were significant differences in measurements of retinal vascular caliber, tortuosity, and fractal dimension among the three ethnic groups. In multiple linear regression model controlling for age, sex, body mass index, systolic blood pressure, cholesterol, and glucose levels, Indians had the largest arteriolar and venular calibers (arterioles [SE]: 158.94 lm [1.00]; venules: 228.26 lm [1.53]), followed by Malays (arterioles: 138.31 lm [0.74]; venules: 204.26 lm [1.13]), and then Chinese (arterioles: 131.20 lm [0.84]; venules: 195.09 lm [1.28]). Chinese had the largest arteriolar and venular tortuosity (arterioles [310 5 ]: 7.20 [0.08; venules [310 5 ]: 9.09 [0.10]), and venular fractal dimension (1.244 [0.003]). There were no statistically significant differences in other retinal vascular parameters after correcting multiple comparisons by the method of modified false discovery rate. CONCLUSIONS. We found that among ethnic groups composed of healthy Chinese, Malay, and Indians, there were statistically significant differences in several retinal parameters. There exist racial influences in retinal vascular parameters and other yet unknown or unmeasured environmental factor or lifestyle habits and genetic variations not related to race that may also contribute to these differences.