Restoring partial vision to a blind patient

Abstract

This paper reports an important breakthrough in partially restoring sight to a man who had lost his vision due to retinitis pigmentosa (RP), a heritable retinal degenerative disease that affects approximately 1 in 4000 people. Long considered an insurmountable challenge, a stellar team of vision scientists, engineers, basic biologists, and others, working together for many years, has enabled a man who had been legally blind for decades to begin distinguishing objects and navigating his environment¹.

Keywords: RGC; Retinitis pigmentosa; cones; retinal ganglion cells; rods.

Figure 1. A man with retinitis pigmentosa who had been blind for decades points to a small object following gene therapy while wearing special goggles

Photoreceptors are the cells in the back of the eye that respond to incoming light and then relay signals through the retina’s complex circuitry to retinal ganglion cells (RGCs). RGCs in turn send information about the outside world through the optic nerve to the visual processing centers of the brain. To restore vision, a gene that codes for a specialized protein, CrimsonR, was introduced into the man’s RGCs. When activated by light, CrimsonR opens a channel that enables electrically-charged particles to flow across the cell’s outer membrane, activating RGCs and causing signals to be conveyed through the optic nerve back to the brain. The goggles that the man is wearing contain a small camera that transmits signals to a computer, which in turn sends signals of the correct wavelength back to the eyes to activate CrimsonR in RGCs and provide the brain with information about the visual scene. A brief video of Dr. Sahel describing this discovery can also be found on YouTube: https://www.youtube.com/watch?v=VtlToPVqJp8. This non-copyright figure was kindly provided by Dr. Sahel.