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Neuroscience
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Biomedical Science
Abstract Type
Research/Clinical
Abstract
Background: Alzheimer’s disease (AD) is the most common form of dementia and one of the leading causes of disability and death in the United States1. Research efforts aim to identify pathological changes that may help support earlier detection of AD and lead to more accessible tools for monitoring disease progression2. The retina is being explored as a potential non-invasive marker of AD, reflecting the shared embryology and microvasculature features between the retina and the brain. Although research has focused on structural changes in retinal vessel diameters and density, few studies have evaluated functional markers of retinal microcirculation. 4. Therefore, we aimed this systematic review to summarize and characterize ocular blood flow and retinal vessel reactivity changes associated with AD.
Methods: Relevant articles were identified through a systematic search of PubMed and Web of Science databases in accordance with PRISMA guidelines5. Exclusion and inclusion criteria were applied, focusing on retinal vessel reactivity, ocular blood flow, Alzheimer's disease, mild cognitive impairment, dementia, and cognitive function. After removing duplicates and articles, a total of 10 studies were selected. The included studies focus on ocular blood flow in patients with AD and involve human subjects only. Data was extracted, study quality was assessed, and findings were qualitatively synthesized and summarized.
Results: A total of 10 articles involving 792 participants were analyzed. These studies differed in methodologies and parameter collection/measurement, and they evaluated cognitively healthy participants, as well as those with mild cognitive impairment to AD; one study focused on individuals with a prior history of ischemic stroke. Ocular blood flow data collection was performed using spectral-domain optical tomography coherence (OCT), OCT-angiography, fundus, static vessel analyzer, and/or dynamic vessel analyzer. Overall, studies documented a decrease in ocular blood flow and retinal choroidal thickness in AD as compared to healthy controls. There was some variation in the foveal avascular zone, with some studies showing small changes in AD while other studies had no significant difference. Density and vessel reactivity, structurally and functionally, were decreased in AD. For instance, in two studies, the retinal arterial reaction time, as measured by Flicker testing, in subjects with AD ranged from 21.5 to 29.3 seconds, whereas it ranged from 15.5 to 25.8 seconds among cognitively healthy individuals. Studies also highlighted that microvascular damage and vascular dysregulation in the brain correlate with markers of ocular blood flow. Lower ocular flow density, smaller retinal vessel diameters, and lower vessel density were linked with lower cerebrovascular reactivity and a greater accumulation of white matter hyperintensities.
Conclusion: Decreased ocular blood flow and vessel reactivity are associated with AD neurodegeneration, including at earlier stages such as those observed among individuals with mild cognitive impairment. Structural and functional changes in the retinal microcirculation seem to correlate with vascular markers associated with AD, such as cerebral small vessel disease and cerebral artery dysregulation. Biomarkers of retinal changes may be helpful in the diagnosis and screening for neurocognitive dysfunction in AD.
Presentation Type
Poster
Recommended Citation
Sayers, Tori; Nichols, Alexa; Ibrahim, Amin; Zwir, Igor; Tsin, Andrew; Flores-Hernandez, Lorena; Maestre, Gladys E.; and Melgarejo, Jesus D., "Ocular Blood Flow and Retinal Vascular Reactivity in Alzheimer’s Disease: A Systematic Review of Retinal Images" (2025). Research Colloquium. 107.
https://scholarworks.utrgv.edu/colloquium/2025/posters/107
Included in
Eye Diseases Commons, Nervous System Diseases Commons, Neurosciences Commons, Ophthalmology Commons
Ocular Blood Flow and Retinal Vascular Reactivity in Alzheimer’s Disease: A Systematic Review of Retinal Images
Background: Alzheimer’s disease (AD) is the most common form of dementia and one of the leading causes of disability and death in the United States1. Research efforts aim to identify pathological changes that may help support earlier detection of AD and lead to more accessible tools for monitoring disease progression2. The retina is being explored as a potential non-invasive marker of AD, reflecting the shared embryology and microvasculature features between the retina and the brain. Although research has focused on structural changes in retinal vessel diameters and density, few studies have evaluated functional markers of retinal microcirculation. 4. Therefore, we aimed this systematic review to summarize and characterize ocular blood flow and retinal vessel reactivity changes associated with AD.
Methods: Relevant articles were identified through a systematic search of PubMed and Web of Science databases in accordance with PRISMA guidelines5. Exclusion and inclusion criteria were applied, focusing on retinal vessel reactivity, ocular blood flow, Alzheimer's disease, mild cognitive impairment, dementia, and cognitive function. After removing duplicates and articles, a total of 10 studies were selected. The included studies focus on ocular blood flow in patients with AD and involve human subjects only. Data was extracted, study quality was assessed, and findings were qualitatively synthesized and summarized.
Results: A total of 10 articles involving 792 participants were analyzed. These studies differed in methodologies and parameter collection/measurement, and they evaluated cognitively healthy participants, as well as those with mild cognitive impairment to AD; one study focused on individuals with a prior history of ischemic stroke. Ocular blood flow data collection was performed using spectral-domain optical tomography coherence (OCT), OCT-angiography, fundus, static vessel analyzer, and/or dynamic vessel analyzer. Overall, studies documented a decrease in ocular blood flow and retinal choroidal thickness in AD as compared to healthy controls. There was some variation in the foveal avascular zone, with some studies showing small changes in AD while other studies had no significant difference. Density and vessel reactivity, structurally and functionally, were decreased in AD. For instance, in two studies, the retinal arterial reaction time, as measured by Flicker testing, in subjects with AD ranged from 21.5 to 29.3 seconds, whereas it ranged from 15.5 to 25.8 seconds among cognitively healthy individuals. Studies also highlighted that microvascular damage and vascular dysregulation in the brain correlate with markers of ocular blood flow. Lower ocular flow density, smaller retinal vessel diameters, and lower vessel density were linked with lower cerebrovascular reactivity and a greater accumulation of white matter hyperintensities.
Conclusion: Decreased ocular blood flow and vessel reactivity are associated with AD neurodegeneration, including at earlier stages such as those observed among individuals with mild cognitive impairment. Structural and functional changes in the retinal microcirculation seem to correlate with vascular markers associated with AD, such as cerebral small vessel disease and cerebral artery dysregulation. Biomarkers of retinal changes may be helpful in the diagnosis and screening for neurocognitive dysfunction in AD.
