A 58-year-old man who has been blind for years now sees well enough to make out shapes, including the white lines of a crosswalk.
The advancement comes thanks to a technology called “optogenetics,” a kind of gene therapy that delivers light-sensing molecules into the eye. The molecules, called opsins, generate an electrical signal when they are exposed to a particular wavelength of light.
In healthy eyes, cells called photoreceptors react to light by sending electrical signals to another type of cell, called ganglion cells. The ganglion cells transmit the signal to the brain.
The patient in the study was diagnosed at age 18 with an eye disease called retinitis pigmentosa, which causes the photoreceptor cells to die. Over time, his vision deteriorated, and when he enrolled in the study, he could…