Combined Therapies May Help Restore Vision Loss From Glaucoma

Past studies have shown that high-contrast visual stimulation can help damaged retinal neurons regrow optic nerve fibers. By combining that knowledge with new research showing that increased activity of a protein called mTOR promotes optic nerve regeneration, scientists are hoping for a way to restore sight lost to glaucoma and other optic neuropathies.
So far, treated mice have regained partial visual function of the optic nerve in research funded through the National Eye Institute (NEI). “Reconnecting neurons in the visual system is one of the biggest challenges to developing regenerative therapies for blinding eye diseases like glaucoma,” said NEI Director Paul A. Sieving, M.D., Ph.D. “This research shows that mammals have a greater capacity for central nervous system regeneration than previously known.”
The optic nerve is the eye’s data cable, carrying visual information from the light-sensing neurons of the retina to the brain. Like a bundle of wires, it consists of about a million axons that each extend from an individual retinal ganglion cell. A variety of optic neuropathies, such as glaucoma, cause vision loss when they destroy or damage these axons. In adults, retinal ganglion cell axons fail to regrow on their own, which is why vision loss from optic neuropathies is usually permanent.
Research on mice was published by the Stanford University School of Medicine’s department of neurobiology and published online in the July 11, 2016 issue of Nature Neuroscience. They found that using gene therapy to increase the “expression” of mTOR in optic nerve damaged eyes significantly improved the efficacy of high-contrast visual stimulation. Within three weeks after the combined procedure, the axons grew about 500 times faster than those receiving visual stimulation alone.
This research was funded by NIH grant EY026100 and the Glaucoma Research Foundation.
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