A New Perspective on Aqueous Humor Circulation-Retina Is a Leading Actor: A Narrative Review

Ocular aqueous humor plays an important role in maintaining retinal function. Recent findings indicate that aqueous humor flowing into the vitreous body is probably absorbed by Müller cells in the retina, and the process is mediated by aquaporin-4. In this review, we aimed to summarize the results of studies on classical aqueous humor circulation and postiridial flow, a pathway proposed in the late 1980s for the inflow of aqueous humor into the vitreous body. We also aimed to discuss the retinal glymphatic pathway, inferred from the recent findings, focusing on the anatomical location of aquaporins and barriers that regulate water movement within the tissue. The function of the retinal glymphatic pathway may decline with age, similar to cerebral glymphatic flow, a phenomenon supported by recent findings. In this review, we discussed age-related ocular diseases that might be associated with dysfunction of the retinal glymphatic pathway.