Ocular Biomarkers in Alzheimer's Disease: Insights into Early Detection Through Eye-Based Diagnostics - A Literature Review

Abstract

Alzheimer's Disease (AD) is a significant challenge in neurodegenerative disorders, characterized by a gradual decline in cognitive functions. Diagnosis typically occurs at advanced stages when therapeutic options are less effective, underscoring the importance of early detection. Traditional diagnostic methods are often invasive and costly, spurring interest in more accessible and economical alternatives. The eye, as a direct link to the brain through the optic nerve, suggests that ocular changes could serve as early indicators of AD. This has led to the exploration of non-invasive ocular diagnostic tools. Technologies such as Optical Coherence Tomography (OCT), OCT Angiography (OCT-A), pupillometry, and eye-tracking, along with electrophysiological methods like Electroretinography (ERG) and Pattern Electroretinography (PEV), are being utilized to investigate potential ocular biomarkers. Further, tear fluid analysis has suggested that presence of amyloid-beta (Aβ) protein might reflect neurogenerative processes, providing a non-invasive window into disease progression. Exploring ocular changes as potential early indicators of Alzhei-mer's Disease (AD), we aimed to provide an overview of promising biomarkers for earlier diagnosis and intervention. Our review further investigates the connections between AD and other ocular degenera-tive diseases such as age-related macular degeneration (AMD) and glaucoma, uncovering shared pathogenic pathways that could offer new therapeutic targets. To establish the sensitivity and specificity of these ocular biomarkers, comprehensive studies are required. Moreover, larger, longitudinal studies are essential to confirm the effectiveness of ocular assessments in the preemptive diagnosis of Alzheimer's Disease.

Keywords: Alzheimer’s Disease (AD); Optical Coherence Tomography (OCT); amyloid-beta (Aβ); early detection; neurodegenerative disorders; non-invasive diagnostics; ocular biomarkers.