Scientists discover hidden drainage system at the back of the eye
The newly found pathway could lead to new treatments for glaucoma and macular degeneration, which affect millions.
Scientists have discovered a hidden drainage system at the back of the eye that could lead to new treatments for diseases like glaucoma and macular degeneration.
The research, conducted in mice, identifies a pathway called posterior ocular lymphatic outflow (POLO).
It shows fluid and waste from behind the retina drain into the body's lymphatic system, a route scientists did not know existed.
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"This gives us a whole new framework for understanding these diseases and a potential target for therapeutics," said Dr. Neeru Gupta, a lead researcher at the University of British Columbia who heads its department of ophthalmology and visual sciences.
The discovery challenges a belief held for more than a century that the eye, unlike nearly every other organ, lacked such a drainage system.
Using MRI, near-infrared fluorescence imaging and microscopy, researchers tracked fluorescent tracer molecules injected into a confined space at the rear of a mouse's eye.
Within minutes, the tracers reached nearby lymph nodes.
The team, from UBC and the University of Toronto, found small lymphatic vessels in the choroid, a vascular tissue located under the retina where there were no lymphatic vessels known previously.
Irreversible blindness from conditions like glaucoma and age-related macular degeneration is often linked to a buildup of fluid, metabolic waste and inflammatory material in the back of the eye.
Age-related macular degeneration alone affects approximately 2.5 million people in Canada.
Dr. Yeni Yücel, who collaborated on the research, stressed the importance of understanding how the retina maintains its delicate balance and flow of materials.
The findings, published in the journal Translational Vision Science & Technology, build on a 2009 discovery by Gupta and Yücel of an “uveolymphatic” drainage pathway in the front part of the eye.
The back portion of the eye was not explored much until now, despite its critical role in numerous serious diseases that lead to vision loss.
Researchers hope understanding this cleanup system will shed light on how pressure, inflammation and fluid movement relate to conditions like glaucoma and age-related macular degeneration.
Dr. Gupta posed the question of how researchers might enhance or leverage this cleanup system for treatment or prevention of ocular diseases.
If the pathway can be strengthened, it could become a target for new therapies aimed at improving fluid clearance to mitigate inflammation and tissue damage.
It might also help deliver drugs to structures deep inside the eye.
These uses remain potential, not established treatments, as the initial experiments were conducted exclusively in mice.
Further research is needed to understand how the POLO pathway functions in humans and whether this drainage system can be enhanced safely.
With files from The News International and SSBCrack