Retinal Microvascular Geometric Parameters and Cerebral Microbleeds

Abstract

Purpose: Retinal vascular changes, as markers of microvascular pathology, have been linked to stroke, cognitive impairment, and even subclinical neuroimaging markers such as silent infarcts and white matter lesions. Cerebral microbleeds have been proposed as novel markers for microvascular pathology in the brain. We examine the association between retinal microvascular parameters and cerebral microbleeds.

Methods: A total of 300 participants (age≥60 years) from the Singapore Chinese Eye Study (SCES) who failed cognitive screening by the Abbreviated Mental Test and the Progressive Forgetfulness Questionnaire were recruited into the Epidemiology of Dementia in Singapore (EDIS) Study. All participants underwent retinal photography, extensive neuropsychological testing and cerebral magnetic resonance imaging (MRI). Retinal vascular parameters (caliber, tortuosity, fractal dimension, etc) were assessed from fundus images using a semi-automated computer-based program. Using the Brain Observer Microbleed Scale (BOMBS), the number of cerebral microbleeds per subject was visually graded from susceptibility weighted imaging (SWI) sequences. Negative binomial regression models were constructed, adjusting for age, gender, smoking status, body mass index, mean arterial blood pressure, fasting blood glucose, blood cholesterol, total white matter hyperintensity volume, total intracranial volume, presence of stroke and intracranial stenosis.

Results: A total of 261 participants who had gradable fundus photographs and MRI scans were included in this analysis. Microbleeds were present in 83 (31.8%) participants, with a range of 0-43 per participant (mean 0.82, variance 10.4) in this study. In multivariate adjusted models, narrower retinal arteriolar caliber (multivariable-adjusted rate ratio (RR) per standard deviation (SD) decrease: 2.23; 95% CI: 1.38-3.61), wider venular caliber (RR per SD increase: 2.39; 95%CI: 1.51-3.79), and smaller arteriolar fractal dimensions (RR per SD decrease: 1.59; 95%CI: 1.27-1.98) were associated with increasing number of microbleeds on MRI. Retinal vascular tortuosity and branching parameters were not significantly associated with microbleeds.

Conclusions: Retinal microvascular parameters were associated with the presence of cerebral microbleeds, suggesting common pathophysiological mechanisms may underlie retinal and cerebral microvascular pathology.

Keywords: 464 clinical (human) or epidemiologic studies: risk factor assessment • 550 imaging/image analysis: clinical • 688 retina