Inspired by cochlear implants that help deaf people hear again, researchers are working on a retinal implant intended to help blind people regain vision.
Designed for people who have lost their vision from retinitis pigmentosa or age-related macular degeneration -- two of the leading causes of blindness -- the implant would act like retinal cells and electrically stimulate the nerve cells that carry visual information from the retina to the brain.
The chip, which is contained in a hermetically sealed titanium case, would not restore vision completely. But it could help the blind more readily navigate a space or identify objects.
The research team, which has been working on the retinal implant for 20 years, is comprised of scientists from Massachusetts Eye and Ear Infirmary, Boston VA Medical Center, Cornell University and MIT.
Patients who receive the implant would wear a pair of glasses with a camera that transmits images to a microchip attached to the patient's eyeball. Inside the glasses, a coil wirelessly transmits power to receiving coils around the eyeball.
When the microchip receives visual data, it activates electrodes that stimulate nerve cells in the areas of the patient's retina that correspond to the features of the visual scene. The electrodes directly activate optical nerves that carry signals to the brain -- bypassing the damaged layers of retina.
The team's new prototype is expected to enter testing in blind patients in the next three years. Their goal is to produce a chip that can be implanted for at least 10 years.
One of the biggest challenges the researchers face is ensuring the patient's eye isn't damaged during surgery or while using the implant. Initial prototypes were attached directly on the retina from inside the eye, which carries more risk of damaging the retina, a delicate area.
The latest version is attached to the outside of the eye, with the electrodes implanted behind the retina. That location reduces the risk of retinal tearing and requires a less invasive surgical procedure.