Quantitative imaging of the clearance systems in the eye and the brain

Wenyu Deng, Crystal Liu, Carlos Parra, Jeffrey R. Sims, Muneeb A. Faiq, Anoop Sainulabdeen, Hana Song, Kevin C. Chan

Abstract

Debilitating neurodegenerative conditions, such as multiple sclerosis, Alzheimer’s and Parkinson’s disease, are often presented with the accumulation of metabolic byproducts in brain tissues. Recent studies also suggest linkages between ocular and cerebral diseases, yet the underlying mechanisms remain unclear (1-5). Unlike the rest of the body, the central nervous system (CNS) does not comprise lymphatic vasculature for metabolic waste removal. Instead, several hypotheses have been proposed that rely on the complex but highly regulated clearance mechanisms responsible for an adequate neuronal environment and fluid homeostasis. Understanding the mechanisms of clearance systems in the eye and the brain can help exploit fluid transport and potentially offer new targets for therapy to the visual system and beyond. In this editorial, we describe and criticize how quantitative imaging can play a role in evaluating different models of clearance systems.