Summary: New research indicates that ultra-wide field retinal imaging may offer a reliable, noninvasive way to monitor neurodegenerative disease progression, including Alzheimer’s disease (AD). The study found increased drusen and distinct vascular changes in the peripheral retina of AD patients.
Source: Queen’s University Belfast.
Researchers at Queen’s University Belfast report for the first time that changes in the eye, particularly the peripheral retina, may reflect brain degeneration such as Alzheimer’s disease.
This clinical study, published in the Journal of Ophthalmic Research, is the first to evaluate ultra-wide field retinal imaging as a potential tool for tracking Alzheimer’s disease progression and other neurodegenerative conditions.
The research team, led by Dr Imre Lengyel, Senior Lecturer at the School of Medicine, Dentistry and Biomedical Sciences at Queen’s University, investigated whether observable features in the eye correlate with pathological changes in the brain.
Working with health professionals and care providers for people with AD, the team examined whether peripheral retinal signs align with Alzheimer’s pathology identified in laboratory models. Based on previous laboratory observations, they hypothesized that peripheral retinal alterations could provide meaningful biomarkers for neurodegeneration.
Using ultra-wide field imaging technology developed by Optos, the researchers identified several retinal differences in AD patients that were most pronounced in the peripheral retina. These findings suggest that imaging beyond the central retina reveals clinically relevant changes.
One notable finding was a higher occurrence of drusen in people with Alzheimer’s disease. Drusen are small yellow deposits made up of lipids, proteins and mineral components such as calcium and phosphate that form between the retina and underlying tissue. While a few drusen are common with ageing, increased number and larger drusen are associated with retinal degeneration.
Dr Lengyel commented: “Our results support the idea that wide-field retinal imaging can capture changes associated with Alzheimer’s disease and therefore could help monitor disease progression.”
The study also identified changes in peripheral retinal blood circulation. Specifically, AD patients often had wider venules near the optic nerve but these vessels narrowed more rapidly than in control subjects as they extended toward the retinal periphery. These combined vascular features are likely to reduce blood flow speed and compromise delivery of oxygen and nutrients to peripheral retinal tissue.
“Eye imaging is fast, well tolerated and far less expensive than brain scans,” Dr Lengyel added. “This makes retinal imaging a practical option for repeated monitoring of patients and for use in clinical settings.”
Although peripheral retinal imaging is not a diagnostic test for Alzheimer’s, its simplicity, speed and low cost make it a promising adjunct to track disease progression in the brain over time.
Professor Craig Ritchie, Professor of the Psychiatry of Ageing at the University of Edinburgh and co-author of the study, noted: “Retinal changes are straightforward to measure compared with many brain-based assessments. Our team identified markers years before dementia onset, opening a window to detect individuals at higher risk who may benefit from early prevention strategies.”
To validate and extend these observations, the team is continuing dementia-related studies and is following patients with very early-stage Alzheimer’s through large-scale projects such as Deep and Frequent Phenotyping. These longitudinal efforts aim to detect and track early signs of Alzheimer’s disease progression using multimodal measurements, including peripheral retinal imaging.
Funding: Research in Dr Lengyel’s laboratory receives support from the Medical Research Council, Economic and Social Research Council, National Institute for Health Research, the Northern Ireland Clinical Research Facility and industrial partner Optos Plc.
Source: Sian Devlin – Queen’s University Belfast
Publisher: Organized by Neuroscience News.
Image Source: NeuroscienceNews.com image in the public domain.
Original Research: Open access research: “Peripheral Retinal Imaging Biomarkers for Alzheimer’s Disease: A Pilot Study” by Lajos Csincsik et al., Journal of Ophthalmic Research. Published April 5, 2018.
doi: 10.1159/000487053
Queen’s University Belfast. “Why the Eyes Could be the Window to Neurodegenerative Diseases, Like Alzheimer’s.” Neuroscience News. 25 June 2018.
Abstract
Peripheral Retinal Imaging Biomarkers for Alzheimer’s Disease: A Pilot Study
Purpose: To evaluate whether ultra-wide field (UWF) retinal imaging can identify biomarkers associated with Alzheimer’s disease (AD) and its clinical progression.
Methods: Ultra-wide field scanning laser ophthalmoscope (Optos P200C AF) images were obtained from 59 patients with AD and 48 healthy controls at baseline. Participants were invited for a two-year follow-up and re-imaged when possible. Blood samples were collected for genotyping at baseline. Images were graded for age-related macular degeneration-like pathologies and retinal vascular parameters. Statistical comparisons between AD patients and controls used Student’s t-test and χ2 tests.
Results: At baseline, a significantly higher prevalence of peripheral hard drusen was observed in AD patients (14/55; 25.4%) versus controls (2/48; 4.2%). After two years, drusen number had increased markedly in those with AD compared to controls. The study also found a significant increase in venular width gradient and a decrease in arterial fractal dimension in AD patients at baseline, with similar trends at follow-up. These vascular changes suggest altered retinal blood flow patterns related to AD.
Conclusions: Ultra-wide field retinal imaging detected a clear association between Alzheimer’s disease and peripheral hard drusen formation as well as vascular alterations outside the posterior pole. Monitoring pathological changes in the peripheral retina may become a valuable, low-cost tool for tracking Alzheimer’s disease progression alongside established clinical assessments.