New wireless retinal implants from Stanford University researchers convert light transmitted from special glasses into electrical current. The resulting current stimulates the retinal neurons known as bipolar cells.
Results in rat studies suggest that the implants could provide functional vision to patients with retinal degenerative diseases, such as retinitis pigmentosa or macular degeneration.
The implant capitalizes on the electrical excitability of the bipolar cells. The cells process the photoreceptors’ inputs before they reach ganglion cells, which send retinal signals to the brain. By stimulating bipolar cells, the implant takes advantage of important natural properties of the retinal neural network, which produces more refined images than the devices that skip these cells.
The silicon implant is composed of hexagonal photovoltaic pixels. The pixels convert light transmitted from special glasses worn by the recipient into the electrical current. The electrical pulses then stimulate the retina’s bipolar cells, triggering a neural cascade that reaches the brain.
A clinical trial is planned next year in France, in collaboration with a French company called Pixium Vision. Initially, patients blinded by a genetic disease called retinitis pigmentosa will be included in the study.
