Prosthetic vision, often called the “bionic eye”, constitutes an artificial device implanted into the eye, usually in association with special glasses and electronics outside the eye, that together enable a person who is blind or partially sighted to see. The most successful implants to date have been those that contain a chip that is implanted into the eye, either on or under the retina. These implants contain an array of micro electrodes and are inserted via a surgical procedure. With these prosthetics, people can perceive light and dark, and certain edges between light and dark, but to date they are unable to perceive detailed images.
In order to improve this ability, various researchers have been trying to increase the number of electrodes that are contained on the implanted chip. This will help improve the image quality but the jury is still out as to whether it will improve it sufficiently to enable people to have useful vision.
I have just come across a new technique which, although in its early stages, appears to offer the possibility of a much clearer, more defined image while at the same time avoiding the need for surgery. The new technique is described in a lecture given by one of its primary inventors, Dr Sheila Nirenberg, available at the following link: http://www.ted.com/talks/sheila_nirenberg_a_prosthetic_eye_to_treat_blindness.html
Dr Nirenberg and her team at Weill Cornell Medical College in New York, working with mice, were able to determine the special code that retinal cells use to translate light stimulation into messages that the brain can interpret. Using a special pair of glasses imbedded with a computer processer that employed her special code, Dr Nirenberg was able to recreate the “fine tuning” that occurs in the normal retina. A second aspect of this procedure required that the nerve cells in the retina be activated in order to make them sensitive to light. This was done by an injection into an experimental mouse that transferred a special activating protein into the mouse’s retinal cells. When the light was then transmitted through the specially coded glasses to the retina, it was in turn transmitted in the same understandable format to the brain. It appears from an analysis of these signals that the mouse is seeing, but since no mouse can speak, it is still a little early to reach this conclusion.
Nirenberg has demonstrated the effectiveness of this process in a number of mice and, more recently, in monkey models. Since human eyes are closest to monkey eyes, it is anticipated that this technique should show similar results in humans. Trials in humans are expected to begin within the next few years.
It is always exciting when a new discovery appears to have the potential to provide sight to those that have lost it. It is still too early to become exuberant over this discovery, but it does appear to have all the makings of a major breakthrough in this area. Time alone will tell.