Vision normally begins when rods and cones, also called photoreceptors, respond to light and send signals through the retina and the optic nerve to the visual cortex of the brain, where visual images are formed. Unfortunately, photoreceptors degenerate and die in some genetic diseases, such as RP. Both mice and humans go progressively blind because with the loss of rods and cones there is no signal sent to the brain.
This study, funded by the National Eye Institute (NEI) of the NIH, raises the intriguing possibility that visual function might be restored by conveying light-sensitive properties to other surviving cells in the retina after the rods and cones have died. Principal investigator Zhuo-Hua Pan, Ph.D., of Wayne State University School of Medicine, and his colleagues, using a gene-transfer approach, introduced the light-absorbing protein ChR2 into the mouse retinal cells that survived after the rods and cones had died. These cells became light sensitive and sent signals through the optic nerve to the visual cortex.
"This innovative gene-transfer approach is certainly compelling," said Paul A. Sieving, M.D., Ph.D., director of vision research at the NIH. "This is a clever approach that offers the possibility of some extent of vision restoration at some time in the future." In addition to RP, there are many forms of retinal degenerative eye diseases that possibly could be treated by gene-based therapies.
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NIH/National Eye Institute