Abstract
sBackgroundThe retina and brain share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) using optical coherence tomography angiography (OCTA).MethodsIn this cross-sectional study, 24 AD participants, 37 MCI participants, and 29 controls were diagnosed according to internationally accepted criteria. OCTA images of the superficial and deep capillary plexus (SCP, DCP) of the retinal microvasculature were obtained using a commercial OCTA system (Zeiss Cirrus HD-5000 with AngioPlex, Carl Zeiss Meditec, Dublin, CA). The main outcome measures were vessel density (VD) and fractal dimension (FD) in the SCP and DCP within a 2.5-mm ring around the fovea which were compared between groups. Perfusion density of large vessels and foveal avascular zone (FAZ) area were additional outcome parameters.ResultsAge, gender, and race did not differ among groups. However, there was a significant difference in diabetes status (P = 0.039) and systolic blood pressure (P = 0.008) among the groups. After adjusting for confounders, AD participants showed significantly decreased VD in SCP and DCP (P = 0.006 and P = 0.015, respectively) and decreased FD in SCP (P = 0.006), compared to controls. MCI participants showed significantly decreased VD and FD only in SCP (P = 0.006 and P < 0.001, respectively) and not the DCP (P > 0.05) compared with controls. There was no difference in the OCTA variables between AD and MCI (P > 0.05). Perfusion density of large vessels and FAZ area did not differ significantly between groups (P > 0.05).Conclusions and relevanceEyes of patients with AD have significantly reduced macular VD in both plexuses whereas MCI participants only showed reduction in the superficial plexus. Changes in the retinal microvasculature and capillary network may offer a valuable insight on the brain in AD.
Highlights
Alzheimer’s disease (AD) is a significant cause of dementia and has important implications for patients and their families
Changes in the retinal microvasculature and capillary network may offer a valuable insight on the brain in AD
Of the 165 participants who were enrolled and imaged between December 2018 and October 2019, we excluded participants who were unable to complete optical coherence tomography angiography (OCTA) scanning due to fatigue (n = 15), poor scan quality (n = 53), and presence of eye diseases such as glaucoma, vascular or nonvascular retinopathies, and age-related macular degeneration which were ascertained from both fundus photographs and OCTA scans (n = 7), leaving 24 AD participants, 37 mild cognitive impairment (MCI) participants, and 29 control participants with good quality OCTA for analysis
Summary
Alzheimer’s disease (AD) is a significant cause of dementia and has important implications for patients and their families. The retina and brain share many neuronal and vasculature characteristics [2], and potential biomarkers may be present in the retina. Optical coherence tomography angiography (OCTA) is a recent innovation that allows for further quantification of the retinal microvasculature and visualization of capillaries measuring 5–15 μm in diameter, which may be more representative of the entire microvascular network [5, 6]. The OCTA may be a potential non-invasive optical imaging tool to determine the presence and role of microvascular dysfunction in AD and cognitive impairment. The retina and brain share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) using optical coherence tomography angiography (OCTA)
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