Optical coherence tomography angiography in Alzheimer’s disease: a systematic review and meta-analysis

Abstract

BACKGROUND:To assess the association between optical coherence tomography angiography (OCTA) retinal measurements and Alzheimer's disease (AD). METHODS: We searched MEDLINE and EMBASE from inception up to October 28th, 2020 for studies assessing the association between OCTA retinal measurements and AD. Estimates from eligible studies were meta-analysed and pooled standardized mean differences (SMDs) between AD patients and healthy participants with corresponding 95% confidence intervals (95% CI) were calculated, using the Hartung-Knapp/Sidik-Jonkman random-effects method. In addition, we quantified the minimum strength on the risk ratio scale (E value) required for an unmeasured confounder to nullify these associations. RESULTS: Ten eligible studies for our systematic review were identified through our search strategy. The pooled SMD between the retinal vessel density of AD patients and healthy participants in the whole superficial vascular plexus (SVP), parafoveal SVP and foveal avascular zone (FAZ) was −0.41 (95% CI: −0.69 to −0.13, p value = 0.01, I 2 = 15%, seven studies), −0.51 (95% CI: −0.84 to −0.18, p value = 0.01, I 2 = 40%, six studies), and 0.87 (95% CI: −0.03 to 1.76, p value = 0.05, I 2 = 91%, seven studies), respectively. An unmeasured confounder would need to be associated with a 2.26-, 2.56-and 3.82-fold increase in the risk of AD and OCTA retinal measurements, in order for the pooled SMD estimate of vessel density in whole SVP, parafoveal SVP and FAZ, respectively, to be nullified. CONCLUSIONS: In our study, whole and parafoveal SVP vessel density were inversely associated with AD. However, prospective longitudinal studies with larger sample sizes are needed to furtherly assess these associations.

Research Trends and Hotspots of Retinal Optical Coherence Tomography: A 31-Year Bibliometric Analysis

“…The emerging research on Alzheimer’s disease has benefited from the quantitative OCT/OCTA analyses that have extended into neurodegenerative disorders. Evidence has shown the retinal thickness and microvascular abnormalities associated with Alzheimer’s disease [ 9 ]. Nowadays, OCT/OCTA-based deep learning algorithms have been applied in the classification tasks for various diseases and segmentation tasks, including the delineation of macular edema [ 61 ].…”

“…The rapid development of OCT has sparked great interest in retinal research over the years. Thousands of publications have reported the advanced OCT technology and clinical applications, and systematic reviews and meta-analyses have focused on specific questions of retinal OCT research [ 8 , 9 ]. With the significant growth in the production of research literature, novel approaches are required to review and analyze the trends within the domain of retinal OCT knowledge [ 10 ].…”

Analysis of Microvascular Abnormalities in Obesity: A Comparative Study with Healthy Subjects Using Swept Source Optical Coherence Tomography Angiography and Adaptive Optics

“…Furthermore, the size of the FAZ appears to get altered during other systemic conditions, including neurodegenerative diseases. Previous studies have shown FAZ widening associated with a decreased vascular density in patients with Alzheimer’s disease [25, 26].…”

Retinal Vascular Study Using OCTA in Subjects at High Genetic Risk of Developing Alzheimer’s Disease and Cardiovascular Risk Factors

“…AD is characterized by the loss of brain neurons and by cerebrovascular changes in small vessels that are difficult to detect using the available brain imaging technologies [ 8 ]. Due to the similarities between the retinal and cerebral vasculature, which share embryological origin as well as physiological and anatomical properties [ 9 ], it seems logical to use the retina and its vascular network to understand the characteristics of vascular cerebral pathologies [ 10 , 11 ].…”