Jung-Hwan Albert Lim, a graduate student at the University of California-San Diego, is the lead author. Glaucoma affects over 70 million people across the globe, and there is now no cure for it.
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According to a story published on the topic by Time News, “Once the optic nerve that’s responsible for sight is damaged, it’s impossible to see again”.
Cells known as ganglions lie in the retina. “Glaucoma is not as clean and easy as crushing the nerve, which is quick and dirty and all the nerve cells die at once”.
Cells in the back of the retina, called photoreceptor cells, react to light which sends information through ganglion cells.
Optic nerves transmit impulses from the eye to the brain.
“Somehow the brain can interpret these electrical signals to say, ‘Wow, that’s a fast-moving vehicle coming my way – I’d better get back on the sidewalk, ‘” said Huberman.
“In humans we have about 1 million cells connecting each eye to the brain”, Huberman said in an interview with Live Science. Huberman said that, although they could prove that the axons were able to reach both the brain and the eye, some important molecular indicators are still missing, which do not allow the eye to determine which subtype of ganglion cell is linked to a particular axon.
Vision loss can also be the result of injuries, retinal detachment, pituitary tumors, and various brain cancers, among other causes.
“When those cells” axons are severed, it’s like pulling the vision plug right out of the outlet’.
Mammalian axons located outside the central nervous system do regenerate, though.
Adult brain cells lose the capacity to regenerate over time because an intracellular pathway that encourages growth known as the mTOR pathway becomes less active in these cells.
The researchers used genetic manipulation to turn this switch back on-activating the so-called “mammalian target of rapamycin” (mTOR) signaling pathway, which helps stimulate growth-and then they exercised the damaged eye, putting it to work by showing the mouse a display of moving, high-contrast stripes.
Three weeks later, the “both” group had recovered their ability to respond to visual stimuli.
But Dr. Harry Quigley, director of the Glaucoma Center at the Johns Hopkins’ Wilmer Eye Institute in Baltimore, warned that people blinded due to nerve damage should not get their hopes up for an impending cure based on these results.
The current set of experiments combined the two procedures and after lengthy experimentation, scientists had concluded that the link offered by the optic-nerve cables had been successfully restored, granting partial sight.
The work was done on visually impaired mice and with such promising results, it is hoped that humans one day will also benefit from this revelation.
“Somehow these retinal ganglion cells’ axons retained their own GPS systems”, Huberman said. He also pointed out that our retinal cells would have to grow a lot more than a mouse’s to rewire vision.
One test projected an expanding dark circle onto the damaged eye, meant to give the impression of a bird of prey’s approach. To do the experiments, researchers first had to crush the optic nerve in mice. The study shows that a regenerating axon can grow in the right direction, forming the connections needed to restore function. But a group of USA scientists has upended that thinking and helped mice with destroyed optic nerves to see again.
In experiments created to test the visual prowess of the once blind mice, the Stanford University researchers noted behavioral changes which implied that sight was partially accessible to the rodents. “We’re working on that now”, he added.
The study was conducted in collaboration with researchers at UCSD, Harvard University and Utah State University.
However, the researchers emphasize that the eye was not exactly as good as new.
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