The advent of advanced retinal imaging technologies has transformed the understanding of microvascular health, providing a unique window into systemic diseases such as cardiovascular, neurological, and metabolic conditions. Optical coherence tomography angiography (OCTA), a cutting-edge imaging technique, enables precise visualization and quantification of retinal vascular parameters, including vessel density, perfusion, and fractal dimensions. This paper explores the pivotal role of OCTA in the early detection and prediction of systemic diseases, focusing on its capabilities to identify subtle vascular changes associated with conditions like hypertension, diabetes, and neurodegenerative disorders. The study emphasizes the importance of quantitative retinal analysis, discusses the integration of machine learning algorithms, and evaluates the potential of retinal imaging as a routine diagnostic tool for comprehensive systemic health assessments.