Effect of Birth Parameters on Retinal Vascular Caliber

Abstract

Abstract-Recent studies reported an association between smaller birth size and narrower retinal vascular caliber, but it remains unclear whether this association is attributed to confounding by shared environment or genetic factors. At a mean age of 9.3 years, 266 twins (49 monozygotic and 84 dizygotic pairs) in the Twins Eye Study in Tasmania underwent an ophthalmic examination including retinal photography. Retinal vascular caliber was measured using a validated protocol. The majority of these twins were also in the Tasmanian Infant Health Study, which prospectively collected data on birth parameters and antenatal maternal factors. We conducted the main analysis using linear mixed models, accounting for birth set clustering. Key Words: twins Ⅲ epidemiology Ⅲ blood pressure Ⅲ arterioles Ⅲ birth weight Ⅲ birth length Ⅲ head circumference E vidence to support the hypothesis of the fetal origins of adult disease has accumulated in the last decade. 1,2 Widely reported data from epidemiological studies implicate adverse influence during fetal, infant, and early childhood growth that might ultimately lead to the early onset of cardiovascular diseases, hypertension, and diabetes. 3 The specific mechanisms underlying these associations, however, are far from clear.Study of retinal microvascular changes attributed to fetal and perinatal influences offers a unique opportunity to uncover the underlying causal pathways of fetal origins of adulthood vasculopathies. Using new computer-based retinal imaging techniques, we have shown that precisely measured retinal arteriolar narrowing is a strong marker for the development of hypertension and cardiovascular events, including myocardial infarction. 4 -6 New studies now demonstrate that lower birth weight is associated with narrower retinal arterioles, 7,8 narrower bifurcation angle, 9 higher retinal vessel tortuosity, and optimality deviance, 10 providing initial evidence that fetal origins of cardiovascular disease may partly be mediated by the microcirculation. However, it could be argued that the association between birth weight and microvascular alternation may be confounded by genetic or shared environmental factors (eg, maternal nutrition) that affect both birth size and abnormal microvascular structural development. It is also commonly understood that variation in almost all human traits and diseases has some genetic component, and this is evident for retinal vascular caliber 11,12 and size at birth. 13

Medical Record Validation of Maternal Recall of Pregnancy and Birth Events From a Twin Cohort

“…We are aware of only one other study that reports recall of birth length, which showed accurate recall but only 6–10 weeks after delivery (Troude et al, 2008). Birth length has been demonstrated to be an independent predictor for various health outcomes (Maehle et al, 2010; Melve et al, 2000; Sun et al, 2009), and may actually serve as a better indicator of birth size than birth weight (Silva et al, 2008). Thus, while there may be growing interest in obtaining this information, our finding highlights the need for researchers to use caution when relying on maternal reports of birth length.…”

Associations Between Depression and Anxiety Symptoms and Retinal Vessel Caliber in Adolescents and Young Adults

“…As described elsewhere (39, 44), all of the twins had 10° stereoscopic optic disc–centered photographs using a Nidek 3-Dx/F fundus camera (Nidek) after dilatation of the pupils with tropicamide 1% or cyclopentolate 1%. Photographs were digitalized, and retinal vessel caliber was measured with computer-assisted software (IVAN, University of Wisconsin, USA) according to a standardized protocol (45).…”

“…Estimates were summarized as the central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE), representing the average caliber (diameter) of arterioles and venules of the eye, respectively, using a revised Knudtson-Parr-Hubbard formula (46). Reliability of the retinal vessel measurement has been published elsewhere (44). Intragrader variation was assessed in 67 randomly selected retinal photographs.…”

Retinal Vascular Caliber Measurements: Clinical Significance, Current Knowledge and Future Perspectives

“…In a sample of 1,369 young children, Mitchell et al [68 ]found that the mean retinal arteriolar caliber was narrowed by 2 µm per 1 kg reduction in birth weight. Data from the Twin Eye Study in Tasmania also showed that children who were born small had smaller mean retinal arterioles [69]. In contrast, previous data from the Singapore Cohort Study of the Risk Factors for Myopia and the Avon Longitudinal Study indicated that neither low birth weight nor preterm birth was associated with narrowed retinal arterioles [70,71].…”