CERA researchers have revealed how a microscopic power grid in the eye sends blood flow to the nerve cells in the retina that are needed for vision.
The new findings, published in Nature Communications, demonstrate for the first time how tiny tubes in the retina direct the flow of blood, sending a supply oxygen and nutrients to the cells that need them most.
The retina – the tissue at the back of the eye which converts light into signals that are sent to the brain to enable vision – is one of the most energy hungry tissues in the body.
The pre-clinical research, led by CERA’s Head of Visual Neurovascular Research Associate Professor Luis Alarcon-Martinez, shows what happens when this system breaks down and nerve cells cannot access the energy they need.
Scientists have long known that the active parts of the retina and brain get more blood – but this study is the first to show how the body decides where to send it.
“Our discovery could change how scientists understand vision loss linked to poor blood flow to the retina – including diseases such as ischemic retinopathy, diabetic retinopathy, glaucoma, retinopathy of prematurity or vision loss caused by stroke,” says PhD candidate Jesse Gardner Russell, who was co-first author on the paper with Mahmoud Haddara.
“It also points to new targets for treatments. The finding challenges the assumption that simply restoring blood flow after injury is enough to protect vision.
“Where the blood flow goes may matter just as much as how much blood there is.”
Blood-flow ‘conversation’
The new study shows how tiny tubes – known as Interpericyte Tunnelling Nanotubes – that connect blood vessels help coordinate this process.
The tubes coordinate the movement of blood around the retina, helping shift it from quieter areas towards cells that are working harder.
WATCH: Interpericyte Tunnelling Nanotubes connect blood vessels. The left vessel has faster blood flow while the right vessel has slower blood flow. After a light flash, the left vessel slows down, and the right vessel speeds up.
The findings build on earlier work by Associate Professor Alarcon-Martinez and Professor Adriana Di Polo (University of Montreal) who for the first time discovered how these tiny tubes linked pericytes, the tiny cells that help vessels control how much blood flows through them.
CERA’s latest study has used experimental real-time imaging techniques in mice to show how blood vessels ‘talk’ to each other and direct blood to the most energy-hungry nerve cells.
Watching the process flowing through the retina, they found the tubes often connected two nearby vessels, one carrying faster blood flow and one slower blood flow.
Each vessel supplied a different group of nerve cells. One group of nerve cells remained active in light, while another group remained active in darkness.
When light switched from one group of cells, the tubes helped redirect blood towards the cells that need it most.
But when the tubes were damaged, the coordination broke down. Blood kept flowing but to the wrong places and nerve cells died as a result.
“It’s a bit like a power grid losing its coordination,” says Gardner-Russell.
“Instead of routing power to the factories that need it most, it just sends an even, untargeted amount to everyone. It’s still technically working but no longer meeting demand where it matters
“The finding challenges the assumption that simply restoring blood flow after injury is enough to protect tissue.
“Where the blood goes may matter just as much as how much of it there is.”
Treatment targets
The CERA team also tested a drug that blocks an enzyme responsible for breaking down the tubes.
Blocking it preserved the tubes, the blood flow and the neurons they supplied. CERA’s team is now working on drugs that could help the tubes regrow.
Associate Professor Alarcon-Martinez says the implications of the study may also apply to glaucoma and the damage caused to optic nerve cells.
“It opens a new line of enquiry into glaucoma, where medications and surgery can successfully lower pressure inside the eye, but vision loss often continues regardless,” says Associate Professor Alarcon-Martinez.
“We believe the vascular dysfunction seen in glaucoma may result from the breakdown of tunnelling nanotubes or their poor regrowth. If that’s confirmed, it would reveal a cause of glaucoma that current treatments don’t address at all.”
Next steps
The team will investigate if this same blood-routing system exists elsewhere in the brain, starting with the visual cortex.
“We are also investigating if we can detect these changes in humans, using current imaging devices that are available in eye clinic,” says Haddara.
“While our research is not a cure, it gives researchers a clearer target: not just restoring blood flow but restoring the system that knows where to send it.”
The research was funded by the Alcon Research Institute, Fighting Blindness Canada, Perpetual IMPACT via the Lionel and Yvonne Spencer Trust and the CERA Foundation.
Read the research
Gardner-Russell, J., Haddara, M., Wang, A.Y.M. et al. Blood flow patterns in mice are regulated by interpericyte tunneling nanotubes connecting functionally-opposite neuronal areas. Nat Commun 17, 5141 (2026). https://doi.org/10.1038/s41467-026-71804-2
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The key to solving vision loss and blindness with tunnelling nanotubes.
