PURPOSE: To examine the relationships of retinal vascular caliber with optic disc, macular, and retinal nerve fiber layer (RNFL) characteristics as measured with optical coherence tomography (OCT). DESIGN: Observational cross-sectional study. METHODS: This study included a subset of healthy children enrolled in the Singapore Cohort Study of the Risk Factors of Myopia (SCORM). Optic disc, macular, and RNFL morphology were measured with Stratus OCT 3. Digital retinal photography was performed and retinal arteriolar and venular caliber measured using validated imaging software. RESULTS: One hundred and four children (mean age 11.51 +/- 0.52 years; 50% male) were included. In multivariate analyses, smaller horizontal integrated rim width and rim area were associated with narrower retinal arterioles and venules (all P < .05), and shorter horizontal rim length was associated with narrower venules (P = .04). Optic disc diameter was not associated with arteriolar or venular caliber. Larger vertical cup-to-disc ratios and cup-to-disc-area ratios were associated with narrower venules but not arterioles (P = .01 and P = .003, respectively). A thinner average RNFL measurement was associated with narrower arterioles and venules, and smaller total macular volume was associated with narrower venules. CONCLUSIONS: Thinner optic disc rims and RNFL measurements were associated with narrower retinal arterioles and venules, and larger cup-to-disc ratios with narrower venules. These findings suggest that retinal vessel caliber varies systematically with morphologic differences in the optic nerve head, retina, and macula.