Hope for regaining lost sight due to glaucoma


Emobileclinic Researchers’ Corner

The challenge of regaining a lost sight after glaucoma infection of the eyes has been of great concerns to health practitioners and the patients as well. There has been no cure for it once the eyes got damaged by the disease condition. However, a new study offers hope of regaining lost sight.

In their laboratory investigation on mice, they found that a combination of two treatments; visual stimulation and molecular manipulation, makes the severed optic nerve of lab mice partially grow back. This breakthrough was published online in the Nature Neuroscience by researchers at the University of Stanford.

Glaucoma is the second leading cause of blindness; it is caused by damage to the optic nerve, which connects the eye to the brain. The optic nerve is part of the central nervous system, which is notorious for failing to recover from injuries. That is why spinal neurons that get crushed in an accident do not bounce back.

Scientists have put a lot of effort into figuring out how to make neurons recover, and are still searching for a cure for diseases that result from nerve damage, like spinal trauma or glaucoma.
The retina, a thin layer of cells lining the back of the eye, converts light into electrical signals and sends them to the brain so we can see. These signals pass through the optic nerve, which is made up of over a million retinal ganglion cells (RGCs) tiny orbs with long tails called axons. The axons form a web of wires reaching from the eye to parts of the brain specializing in different aspects of vision, like the color blue, a moving car, or the distance between your foot and the sidewalk. The RGCs are the only bridge between the eye and the brain. If the RGCs are injured, the result is irreversible vision loss even if the eye and the brain are functioning normally.

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Huberman and his team crushed the RGCs of laboratory mice and then exposed them to one or a pair of treatments: a virus that promotes the growth of cells, and exposing them to videos of moving black and white lines.
Mice that experienced only visual stimulation had their RGCs partially grow back, though their axons did not get long enough to reach the brain a result that previous studies have also found.
On its own, injecting a virus that reactivates a growth pathway called mTOR also got the RGCs to regenerate partially. But again, they did not make the full distance to the brain.
When the two therapies were combined, however, not only did the RGC axons grow long enough to make it back to the brain, but they also found and reconnected with their correct targets.
There are about 30 types of RGCs, and each sends its axons to a different and specific location in the brain. “It’s a very intricate wiring system,” explained Huberman. The fact that the axons found their way back to the right place was “incredibly reassuring,” he said.

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