One man’s trash is another man’s treasure, even at the level of the cell. That’s where—according to new research—a waste product of the retina fuels part of the eye that powers the rods and cones that help us sense light. Without this waste, that part of the eye “steals” glucose from the retina, leading to the death of retinal cells and likely vision loss. The finding could help explain why eyesight degenerates with age—and in diseases such as macular degeneration and diabetes.
“It’s almost a revolutionary concept” that there is such a tight coupling between the two parts of the eye, says Stephen Tsang, a retina specialist at Columbia University who was not involved in the work.
Rods and cones are very active, and they need a lot of energy to do their jobs. Exactly how they get this energy has long been a mystery. In previous studies, researchers showed that a layer of cells beneath the retina, the retinal pigment epithelium (RPE), ferries glucose from the blood to the retina. But it was unclear why the RPE didn’t keep the glucose for itself.
After a decade of study, biochemist James Hurley at the University of Washington in Seattle and his colleagues have now shown that the retina’s rods and cones burn the glucose, convert leftovers into a fuel called lactate, and then feed that back to the RPE. “There is a growing consensus that no cell exists on its own in complex tissues like the retina,” says Martin Friedlander, an ophthalmologist at The Scripps Research Institute in San Diego, California, who was not involved with the new work.
To precisely map how glucose and lactate move around in the eye, Hurley and colleagues grew human RPE in…