Peripheral Retinal Imaging Biomarkers for Alzheimer’s Disease: A Pilot Study

• Published in: Ophthalmic research Vol. 59; no. 4; pp. 182 - 192
• Main Authors: Csincsik, Lajos, MacGillivray, Thomas J., Flynn, Erin, Pellegrini , Enrico, Papanastasiou, Giorgos, Barzegar-Befroei, Neda, Csutak, Adrienne, Bird, Alan C., Ritchie, Craig W., Peto, Tunde, Lengyel, Imre
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland 01.01.2018
• Subjects: Original Paper; Peripheral retina; Vascular biomarker; Drusen; Alzheimer’s disease; Fractal dimension; Age-related macular degeneration; Image grading; Tortuosity; Imaging
• ISSN: 0030-3747; 1423-0259
• DOI: 10.1159/000487053

Purpose: To examine whether ultra-widefield (UWF) retinal imaging can identify biomarkers for Alzheimer’s disease (AD) and its progression. Methods: Images were taken using a UWF scanning laser ophthalmoscope (Optos P200C AF) to determine phenotypic variations in 59 patients with AD and 48 healthy controls at baseline (BL). All living participants were invited for a follow-up (FU) after 2 years and imaged again (if still able to participate). All participants had blood taken for genotyping at BL. Images were graded for the prevalence of age-related macular degeneration-like pathologies and retinal vascular parameters. Comparison between AD patients and controls was made using the Student t test and the χ 2 test. Results: Analysis at BL revealed a significantly higher prevalence of a hard drusen phenotype in the periphery of AD patients (14/55; 25.4%) compared to controls (2/48; 4.2%) [χ 2 = 9.9, df = 4, p = 0.04]. A markedly increased drusen number was observed at the 2-year FU in patients with AD compared to controls. There was a significant increase in venular width gradient at BL (zone C: 8.425 × 10 –3 ± 2.865 × 10 –3 vs. 6.375 × 10 –3 ± 1.532 × 10 –3 , p = 0.008; entire image: 8.235 × 10 –3 ± 2.839 × 10 –3 vs. 6.050 × 10 –3 ± 1.414 × 10 –3 , p = 0.004) and a significant decrease in arterial fractal dimension in AD at BL (entire image: 1.250 ± 0.086 vs. 1.304 ± 0.089, p = 0.049) with a trend for both at FU. Conclusions: UWF retinal imaging revealed a significant association between AD and peripheral hard drusen formation and changes to the vasculature beyond the posterior pole, at BL and after clinical progression over 2 years, suggesting that monitoring pathological changes in the peripheral retina might become a valuable tool in AD monitoring.