In a seeing person with a healthy retina, light reflected from an object enters the eye and is detected by retinal photoreceptor cells. The retina processes the visual information encoded by the photoreceptors, producing spikes in retinal output neurons that are transmitted to the brain. Visual centers in the brain, including the visual cortex, then assemble the information from retinal spike trains to produce a conscious perception of the scene and a range of visual behaviors.


Artificial vision can restore sight to the blind

In common forms of retinal degeneration, notably macular degeneration and retinitis pigmentosa, photoreceptors cells are lost, but retinal output neurons typically survive. To restore sight, a camera captures light from the object and translates digital images into electrical signals. An electrode array implanted in the retina then uses these signals to electrically activate the surviving retinal output neurons. This results in transmission of retinal output signals to the brain, producing artificial vision. Existing retinal implants provide a proof of principle that this approach can work. However, major improvements are needed to produce artificial vision that is of great utility to the patient.

A high-resolution electrode array is placed on the inward-facing surface of the retina, in close proximity to retinal ganglion cells, the output neurons of the retina.


Speaking the language of the retina

Our innovative approach focuses on the specific step of stimulus encoding. The retina normally transforms the visual scene into a complex and diverse set of signals transmitted to the brain. How can the implant similarly translate the image captured by the camera into a pattern of electrode array pulses that will produce naturalistic visual signals? Our concept is that only when the electrode array "speaks the language" of the retina will the device produce accurate and meaningful artificial vision. Thus, we rely heavily on our extensive research on the normal encoding performed by the retina to drive our implanted device. This approach based on neuroscience will allow us to precisely mimic normal retinal function in a blind retina.

To learn about the neuroscience behind our unique strategy, visit the Approach page.

To see how our method compares to those employed by other groups, visit the Competition page.