Associations of retinal layer thicknesses and regional brain volumes in UK Biobank

Abstract

Purpose : The eye has proven potential as a marker to understand brain structure and function, yet region-specific structural correlations between the retina and the brain remain underexplored. We therefore aimed to describe the relationships between imaging-derived structural phenotypes of the retinal sub-layers and brains of UK Biobank participants.

Methods : Participants who had both quality-controlled optical coherence tomography (OCT) and brain magnetic resonance imaging (MRI) were eligible for this study. Total retinal and sublayer thickness were derived from OCT scans using the Topcon Advanced Boundary Segmentation tool. Image-derived phenotypes (IDP) of 153 cortical and subcortical regions were processed from structural MRI scans. Consequently, we examined 1530 pairs of retina-brain associations (10 retinal metrics×153 brain IDPs) using linear regression models. All analyses were corrected for multiple testing and adjusted for age, sex, imaging site, the time lapse between OCT and MRI scans, education level, mean arterial blood pressure, body mass index, smoking status, alcohol drinking status, diabetes, and spherical equivalent.

Results : In total, 6446 participants were included in the final analysis. Using multivariable linear regression, we identified several associations between volumetric 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 layers (macular nerve fibre layer [mRNFL], ganglion cell-inner plexiform layer [GCIPL], and ganglion-cell complex [GCC]) and total retinal thickness. Despite sufficient power, we did not observe statistically significant associations between the brain IDPs and the thickness of the mid and outer retinal sub-layers.

Conclusions : Thinner inner and total retinal thickness is associated with smaller volumes of specific brain regions, including the intracalcarine cortex, postcentral gyrus, cerebellum, thalamus, hippocampus, and basal ganglia. The associations we found go beyond anatomically established retina-brain connections. These novel findings will be the subject of further modelling.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Table 1

 

Figure 1