Abstract P55: Retinal Microvascular Parameters Predict Retinal Amyloid Burden and Co-Jointly Predict Verbal Memory

Abstract

Introduction: Retinal vascular features predict cognitive performance and retinal imaging is a non-invasive tool to study brain health. Patients with Alzheimer’s disease (AD)-related cognitive disorders exhibit both retinal vascular abnormalities and intraretinal accumulation of amyloid-beta (Aβ) plaque. Curcumin-enhanced retinal fluorescence imaging (CRFI) was recently translated as a safe imaging tool for retinal Aβ plaque quantification. In this study, we sought to determine whether and which retinal arterial and venous parameters are predictive of retinal Aβ burden and cognitive Z-scores. Methods: We used scanning laser ophthalmoscopy with RetiaTM (Centervue, Inc) to obtain CRFI in a cohort of patients with cognitive decline. Retinal blood vessels were segmented in a predefined circumpapillary region of interest. For each centerline, vessel tortuosity index (VTI), vessel inflection index (VII), and branching angle (VBA) were quantified, independently for arteries and veins. Additionally, we automatically quantified retinal amyloid count in the supero-temporal quadrant and its subregions: posterior pole (PP), proximal mid-periphery (PMP), and distal mid-periphery (DMP). All quantifications were done blinded to the subjects’ clinical characteristics. Linear regression models were used to assess the correlations between retinal vascular and amyloid parameters. Results: 29 subjects (55% female, mean age 64±6 years) were included in the analysis: 11 had normal cognition, 16 mild cognitive impairment and 2 probable AD. Venous VTI was the only vascular parameter significantly different across levels of Clinical Dementia Rate scores and between cognitively normal and impaired. Venous VBA was a significant predictor of DMP amyloid count (p=0.03). Arterial VII significantly predicted PP amyloid count (p=0.02). VBA predicted Wechsler Adult Intelligence Scale Z-score (p=0.08). The combined VTI-PMP amyloid index significantly predicted Wechsler Memory Scale, California Verbal Learning Test and SF-36 mental component score Z-scores (p<0.05). Conclusion: Retinal venous tortuosity discriminates across cognitive scores and in combination with PMP amyloid count may predict verbal memory and related quality-of-life scores.