Optical Coherence Tomography Angiography in the Evaluation of Macular Retinal Microvasculature in Patients in the Early Clinical Stage of Alzheimer’s Disease – A Preliminary Report

Abstract

IntroductionAlzheimer’s disease (AD) is a chronic neurodegenerative condition causing cognitive decline among elderly individuals. In addition to neurological deficits, a key role in the onset and subsequent progression of AD Alzheimer’s disease-specific changes is attributed to vascular factors. Retinal microvasculature and cerebral small vessels share similar anatomical features and physiological characteristics, and damage to the retinal vascular bed can be observed at any stage of AD Alzheimer’s disease. Retinal microvasculature can be visualized and assessed non-invasively using the technique of optical coherence tomography angiography (OCT-A).Aim of studyEvaluation of macular retinal microvasculature in the superficial capillary plexus based on OCT-A optical coherence tomography angiography images in patients diagnosed with the mild stage of Alzheimer’s dementia.Material and methodsThe study involved a total of 21 patients diagnosed with mild Alzheimer’s dementia confirmed by neuropsychological tests and neuroimaging studies. optical coherence tomography angiography OCT-A was used to determine vessel density in the superficial retinal capillary plexus (SRCP), i.e. generate a density map within five-field ETDRS circles with diameters of 3 mm and 6 mm.ResultsAlterations in the macular retinal capillary network were noted in all eyes studied. In the majority of eyes, there was a marked reduction in vessel density reflected in the quantitative metrics in the density map around the FAZ in at least one of the scans obtained for a given eye (3 mm x 3 mm and/ or 6 mm x 6 mm) and in the macroscopic evaluation of the superficial and deep capillary plexuses, capillary thinning, and irregular area/mexpansion of the FAZ.ConclusionsOptical coherence tomography angiography OCT-A has the potential to serve as a valuable tool for screening or monitoring the response to therapies in patients with Alzheimer’s disease AD. However, further research is necessary to standardize study methodologies and determine whether impaired retinal microvasculature in patients with Alzheimer-type MCI or preclinical Alzheimer’s disease AD correlates with the advancement of cognitive decline and loss of neurons and cerebral blood vessels in individual Alzheimer’s disease AD patients and, hence, has clinical utility.