Abstract
Introduction The eye is a well-established model of brain structure and function, yet region-specific structural correlations between the retina and the brain remain underexplored.
Aims To explore and describe the relationships between the retinal layer thicknesses and brain magnetic resonance image (MRI) derived phenotypes in UK Biobank.
Methods Participants with both quality-controlled optical coherence tomography (OCT) and brain magnetic resonance imaging (MRI) were eligible. Retinal sub-layer thicknesses and total macular thicknesses were derived from OCT scans. Brain image-derived phenotypes (IDPs) of 153 cortical and subcortical regions were processed from MRI scans. In this hypothesis-free study, we examined pairwise retinal-brain associations using multivariable linear regression models. All analyses were corrected for multiple testing and adjusted for confounders.
Results Data from 6,446 participants were included in this study. We identified highly significant associations between volumetric brain MRI measures of subregions in the occipital lobe (intracalcarine cortex), parietal lobe (postcentral gyrus), cerebellum (lobules VI, VIIb, VIIIa, VIIIb and IX) and deep brain structures (thalamus, hippocampus, caudate, putamen, pallidum and accumbens) with the thickness of the innermost retinal sub-layers and total macular thickness (all P<3.3×10-5). We did not observe statistically significant associations between brain IDPs and the thickness of the outer retinal sub-layers.
Conclusion Thinner inner and total retinal thicknesses are associated with smaller volumes of specific brain regions. These associations go beyond anatomically established retina-brain connections. Furthermore, the links between the normal variations in retinal and brain structures broaden our understanding of neurological ageing in general population.
