Researchers at Weill Cornell Medical College in New York published a study recently showing that they had "cracked" the code the mouse retina sends to the brain and created a device that can mimic this code in mice with diseased retinas.
Previous retinal microchips or prosthetics stimulated the retina to send simple signals back to the brain, resulting in mostly high-contrast images. This new prosthetic, however, is much clearer and creates "normal vision."
Of course this is all being done with mice right now, but researchers are optimistic and believe that this technique "may be adopted for human use within a year or two." They point out that they have already cracked the retinal code in monkeys.
The study's authors say in the abstract:
"Efforts to improve prosthetic capabilities have focused largely on increasing the resolution of the device’s stimulators (either electrodes or optogenetic transducers). Here, we show that a second factor is also critical: driving the stimulators with the retina’s neural code. Using the mouse as a model system, we generated a prosthetic system that incorporates the code. This dramatically increased the system’s capabilities—well beyond what can be achieved just by increasing resolution."
The retina normally takes signals in through its photoreceptors then transports that information through the retina's ganglion cells to the brain where it is interpreted and turned into an image. This prosthetic device takes the place of damaged photoreceptors, translates the signals into the proper code, then sends the signal on through the retina's ganglion cells. This does mean that the process relies on the retina's ganglion cells still working properly on their own.
To read more about this breakthrough, check out the original study: Retinal prosthetic strategy with the capacity to restore normal vision.