Relationship of Axial Length and Retinal Vascular Caliber in Children

Abstract

Previous studies in older adults suggest that longer axial length is associated with narrower arteriolar caliber. In this study, we re-examined this relationship in a cohort of children, while controlling for the effects of ocular magnification. Cross-sectional study of 767 children aged 7 to 9 years. Retinal vascular calibers were measured from retinal photographs using a computer-based program. Ocular magnification was corrected using the Bengtsson formula. Standardized examination of refraction and ultrasound ocular biometry was performed for all children. In models that adjusted for age, gender, ethnicity, body mass index, blood pressure, and birth weight, longer axial length was associated strongly with narrower retinal arteriolar caliber (3.18-microm decrease per standard deviation increase in axial length; P < .001) and venular caliber (4.62-microm decrease standard deviation increase in axial length; P < .001) before correction for ocular magnification. However, after correction, these associations no longer were significant (0.44 microm; P = .31, change for arteriolar caliber; and 0.70 microm; P = .25, for venular caliber). Our study in children found no association between axial length and retinal vascular caliber after correcting for ocular magnification, suggesting that the previously reported association was likely related to differences in ocular magnification.