RETINAL THICKNESS CORRELATES WITH PARIETAL CORTICAL ATROPHY ON MRI

Abstract

As a protrusion from the brain, the retina might serve as a patient-friendly source of biomarkers reflecting neurodegeneration. Previous research showed thinning of total macular and peripapillary retinal nerve fiber layer (RNFL) thickness measured with OCT in patients with Alzheimer's Disease (AD) compared to controls. This observational pilot aimed to: 1. compare retinal thickness as measured with Spectral Domain OCT (SD-OCT) in amyloid positive, early onset AD (EOAD) patients and controls, and 2. to correlate retinal thickness to cortical atrophy scores on MRI as established AD biomarkers. Twenty five AD patients and 15 controls were included from the Amsterdam Dementia Cohort (Mini-Mental State Examination(MMSE)≥17). All patients met NIA-AA criteria and were amyloid positive in CSF and/or on amyloid-PET. Controls were amyloid negative subjects with subjective cognitive decline (SCD). Subjects underwent a complete neurological and ophthalmological examination including MRI and SD-OCT of the macula and optic disk (Heidelberg, Spectralis). Patients with glaucoma were excluded. Peripapillary RNFL and total macular thickness were measured and correlated with visual cortical atrophy scores on MRI: medial temporal lobe atrophy (MTA), global cortical atrophy (GCA) and parietal cortical atrophy (PCA). Peripapillary RNFL thickness was 93.96μm±8.88 for AD patients versus 97.5μm±6.96 for controls (t-test, p=0.192). Total macular thickness (mean of inner ring and outer ring of ETDRS grid) was 318.3μm±12.2 for AD patients versus 320.5μm±7.5 for controls (t-test, p=0.529). Total macular thickness was significantly correlated with PCA (Spearman's rho= -0.531, p=0.001) but not with GCA (Spearman's rho= -0.220, p=0.185) and MTA (Spearman's rho= -0.135, p=0.419) in AD and controls (figure 1). Peripapillary RNFL and total macular thickness were not significantly decreased in an amyloid positive EOAD cohort without glaucoma compared to controls. Total macular thickness was significantly correlated to PCA on MRI in AD and controls, supporting the hypothesis that neurodegenerative diseases may be reflected by retinal changes. Future research in larger cohorts with established AD biomarkers are needed to assess the exact diagnostic value of retinal thickness for early AD diagnosis. Macular thickness correlates with parietal cortical atrophy in AD and controls