Association of retinal layer thickness with brain volume and cortical thickness in older adults

This study explored associations between macular retinal nerve fiber layer (RNFL) thickness, brain volume, and cortical thickness in older adults. A total of 166 community-dwelling participants over 65 years old (mean 75.2 ± 5.3; 61.4% women) without dementia or ocular pathologies underwent 3D T1 MRI and macular RNFL thickness measurements using spectral-domain optical coherence tomography. Voxel-based morphometry, adjusting for age, sex, and total intracranial volume (uncorrected p < 0.001, cluster size threshold ≥ 100 voxels), showed uncorrected correlations between outer RNFL thickness and gray matter volume in the right inferior parietal (t = 3.81), left superior frontal (t = 3.71), and left inferior temporal (t = 3.95) cortices, with total RNFL thickness linked to the right inferior parietal cortex (t = 3.62). Pearson's correlation, adjusted for age and sex, showed RNFL thickness was weakly associated with cortical thickness in regions including the left posterior cingulate and supramarginal areas. All observed associations lost statistical significance after multiple comparisons. These preliminary findings suggest that macular RNFL thickness may be related to structural changes in brain regions involved in sensory processing and cognitive functions, but the statistical evidence was limited. Further longitudinal research is needed to assess its potential as a non-invasive biomarker for neurodegenerative processes.