New research from Canada has identified what appears to be a previously unknown waste drainage system at the back of the eye.
The discovery gives researchers new opportunities to harness this system to treat retinal diseases associated with buildup of fluid, waste, and inflammatory debris in the eye, including glaucoma and age-related macular degeneration.
Researchers from the University of British Columbia (UBC) and the University of Toronto said the hidden circulatory pathway, called the posterior ocular lymphatic outflow, or POLO pathway, provides a route for fluid and waste to exit the eye and enter the body’s lymphatic system.1
… the team was “surprised to see such a direct route for fluid to leave the eye and connect with the lymphatic system
“The retina is one of the most metabolically active parts of the body, constantly generating byproducts that need to be cleared,” said Professor Neeru Gupta from UBC.2
“This discovery helps explain how the eye flushes this waste and promises to transform how we think about and treat a range of eye conditions.
“This gives us a whole new framework for understanding these diseases and a potential target for therapeutics,” Prof Gupta said. “The question now is: How can we enhance or exploit this cleanup system to treat or even prevent disease?”
To uncover the POLO pathway, Prof Gupta and Professor Yücel, from the University of Toronto, and their team introduced fluorescent tracer molecules into a thin space at the back of the eye in mice, then used advanced imaging to track their movement in real time.
This allowed them to identify small lymphatic vessels in the choroid, a thin layer beneath the retina. Fluid drained from the back of the eye into surrounding orbital tissue and, within minutes, reached nearby lymph nodes that link the eye to the broader lymphatic system.
Prof Yücel said the team was “surprised to see such a direct route for fluid to leave the eye and connect with the lymphatic system”.
“It suggests the back of the eye has an active clearance pathway, which could play an important role in removing fluid, proteins and inflammatory material that build up in disease.”
Further research is needed to understand how the lymphatic pathway operates in humans and how it could be targeted with therapeutics.
References
- Sauntharrajan B, Gupta N, Yücel YH, et al. Identification and mapping of a posterior ocular lymphatic outflow (polo) pathway through choroidal lymphatics. Trans Vis Sci Tech. 2026;15(7):23. doi: 10.1167/tvst.15.7.23.
- Goldhawk B. Researchers discover the eye’s hidden cleanup system, Medical Xpress, available at: medicalxpress.com/news/2026-07-eye-hidden-cleanup.html [accessed July 2026].
