A newly identified drainage pathway in mice could change scientists understanding of eye diseases and open the door to future treatments for conditions that cause blindness.
Scientists at the University of British Columbia and the University of Toronto have discovered a previously unknown drainage pathway at the back of the eye that moves fluid and waste into the body’s lymphatic system.
The findings, published in Translational Vision Science & Technology, could offer new insights into eye diseases, including glaucoma and age-related macular degeneration.
The pathway, called posterior ocular lymphatic outflow (POLO), was identified after researchers injected fluorescent tracers into a space at the back of a mouse’s eye. Within minutes, the tracers reached nearby lymph nodes, revealing a drainage route that had not been previously recognized.
To track the movement of fluid, the research team used magnetic resonance imaging (MRI), near-infrared fluorescence imaging and microscopy. The experiments revealed tiny lymphatic vessels in the choroid, a layer of blood-rich tissue located beneath the retina.
The discovery challenges a long-standing belief that the eye lacks a conventional lymphatic drainage system. For more than a century, researchers had considered the eye an exception to the drainage systems found in most other organs.
That understanding began to change in 2009, when Dr. Neeru Gupta and Dr. Yeni Yücel identified a drainage pathway known as the uveolymphatic pathway in the front part of the eye. However, the drainage system at the back of the eye remained poorly understood.
The new findings could help researchers better understand how fluid and waste move out of the eye and what happens when these processes do not work properly.
Glaucoma and age-related macular degeneration are among the conditions that can lead to irreversible vision loss. Researchers are investigating how fluid movement, waste clearance and other biological processes contribute to these diseases. Age-related macular degeneration alone affects about 2.5 million people in Canada.
Scientists say the newly discovered pathway could eventually become a target for treatments designed to improve waste clearance in the eye. It may also offer a new way to deliver medications to deeper eye structures.
Dr. Gupta, who heads the University of British Columbia’s Department of Ophthalmology and Visual Sciences, said the discovery provides a new framework for understanding eye diseases.
However, the research was conducted in mice, and further studies are needed to determine whether the pathway functions similarly in humans and whether it can be used to develop effective treatments. For now, the findings represent a promising scientific discovery rather than an established medical breakthrough.
