Association of Visual Impairment with Brain Structure

ObjectiveTo investigate the association of visual impairment (VI) with brain structures in the UK Biobank Study. MethodsThe UK Biobank Study is a large prospective study that recruited more than 500,000 participants aged 40-69 from 2006 to 2010 across the UK. Visual acuity (VA) of worse than 0.3 LogMAR units (Snellen 20/40) was defined as VI. Structural magnetic resonance imaging (MRI) data were obtained using a 3.0-T MRI imager. Volumetric measures of five global brain volumes (total brain volume, total grey matter, total white matter, cerebrospinal fluid (CSF), brain stem) and the volumes of seven specific brain region (thalamus, caudate nucleus, basal ganglia, pallidum, hippocampus, amygdala and nucleus accumbens) were included in the present analysis. Multivariable linear regression was used to investigate the association of VI with global and specific brain volumes. ResultsA total of 8976 participants free of neurological disorders at baseline assessment were included for the present analysis. The prevalence of VI was 0.02% (n=181). After adjusting for a range of cofounding factors, VI was significantly associated with decreased volumes of the total brain ({beta} = -0.12, 95% confidence interval (CI) -0.23 to 0.00, P = 0.049), thalamus ({beta} = -0.16, 95% CI -0.18 to -0.04, P = 0.010), caudatenucleus ({beta} = -0.14, 95% CI -0.27 to 0.00, P = 0.046), pallidum ({beta} = -0.15, 95% CI-0.27 to -0.02, P = 0.028) and amygdala ({beta} = -0.18, 95% CI -0.31 to -0.04, P = 0.012). InterpretationWe found that VI is associated with a decrease in total brain volumes and the volumes of specific brain regions implicated in neurodegenerative diseases.