The Kellogg Eye Center is one of 13 major centers across the country soon to offer a retinal implant that could provide partial sight for individuals with late-stage retinitis pigmentosa (RP).
Sometimes referred to as an artificial retina or “bionic eye,” the Argus® II Retinal Prosthesis System (“Argus II”) was developed by Second Sight Medical Products Inc. and was approved by the Food and Drug Administration (FDA) in February of this year.
RP is an inherited retinal degenerative disease that causes slow but progressive vision loss due to a gradual loss of the light-sensitive retinal cells called rods and cones. Patients with RP experience gradual loss of side vision and night vision, and later of central vision, which can result in near blindness.
In the Argus II System, retina prosthesis is surgically implanted in one eye. The individual wears glasses equipped with a camera that captures images and converts them into a series of small electrical pulses. The pulses are transmitted wirelessly to the prosthesis and its array of electrodes on the surface of the retina. These pulses are intended to stimulate the retina’s remaining cells, resulting in the corresponding perception of patterns of light in the brain. The patient then learns to interpret these visual patterns, thereby regaining some visual function.
“Until now, we’ve had no treatment options to offer our patients with advanced RP,” says Kellogg’s Dr. Thiran Jayasundera, retina surgeon and principal investigator. “The implant will bring light back into our patients’ worlds, allowing them to detect shapes of people and objects in their environment. They will gain more independence and the ability to go about their daily lives with more confidence.”
In a recent clinical study, most participants were able to perform basic activities better with the retina prosthesis than without it. Many were able to locate lights and windows, follow lines in a crosswalk, or avoid running into things as they walked. Some could sort laundry or determine where other people were located in a room, and about half of the subjects were able to read very large letters (about 9 inches high).
Jayasundera and colleagues expect to begin performing the procedure in four to six months. Among the eligibility requirements, potential patients must be 25 years of age with end-stage RP that has progressed to the point of having “bare light” or no light perception in both eyes.
