title: Retinal vascular caliber and the development of hypertension: a meta-analysis of individual participant data.
abstract: OBJECTIVE
  Microvascular dysfunction has been suggested to be a major pathogenic factor for the development of hypertension. We examined the association between retinal vascular caliber, a marker of systemic microvascular dysfunction, and incident hypertension on a meta-analysis of individual participant data.
  
  
  METHODS
  We performed a systematic review with relevant studies identified through a search of electronic databases, a review of reference lists, and correspondence with experts. Studies were included if participants were selected from a general population, retinal vascular caliber was measured from photographs using computer-assisted methods at baseline, and individuals were followed up to ascertain the incidence of hypertension. Prespecified individual recorded data from six population-based prospective cohort studies were included. Discrete time proportional odds models were constructed for each study with adjustment for hypertension risk factors. Log odds ratios (ORs) per 20-μm difference were pooled using random-effects meta-analysis.
  
  
  RESULTS
  Among 10 229 participants without prevalent hypertension, diabetes, or cardiovascular disease, 2599 developed new-onset hypertension during median follow-up periods ranging from 2.9 to 10 years. Both narrower retinal arterioles [pooled multivariate-adjusted OR per 20-μm difference 1.29, 95% confidence interval (CI) 1.20-1.39] and wider venules (OR per 20-μm difference 1.14, 95% CI 1.06-1.23) were associated with an increased risk of hypertension. Each 20 μm narrower arterioles at baseline were associated with a 1.12 mmHg (95% CI 0.25-1.99) greater increase in SBP over 5 years.
  
  
  CONCLUSIONS
  Retinal arteriolar narrowing and venular widening were independently associated with an increased risk of hypertension. These findings underscore the importance of microvascular remodeling in the pathogenesis of hypertension.
authors: aSingapore Eye Research Institute, Singapore National Eye Centre bDepartment of Ophthalmology cInvestigational Medicine Unit, National University of Singapore, Singapore dSydney School of Public Health, University of Sydney, Australia eEye Academic Clinical Program, Duke-NUS Graduate Medical School, Singapore fCentre for Eye Research Australia, University of Melbourne, Australia gDepartment of Ophthalmology & Visual Sciences, School of Medicine & Public Health, University of Wisconsin, Madison hDivision of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA iDepartment of Ophthalmology and Westmead Millennium Institute, Centre for Vision Research, University of Sydney, Sydney jBaker IDI Heart and Diabetes Institute, Melbourne, Australia kThe Global COE Investigators, Yamagata University, Yamagata, Japan lDepartment of Epidemiology, John Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
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mesh_terms: D015331:Cohort Studies; D006801:Humans; D006973:Hypertension / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D055806:Microvessels / Q000473:pathology / Q000503:physiopathology; D011446:Prospective Studies; D012171:Retinal Vessels / Q000473:pathology* / Q000503:physiopathology; D012307:Risk Factors