Argus II retinal prosthesis system on trial at the IEEI
The Illinois Eye and Ear Infirmary is pleased to share this story with you from WBEZ reporting on a Phase Four clinical trial of the Argus II retinal implant headed by IEEI retina surgeon Dr. Jennifer Lim.
The University of Illinois Hospital is screening patients to test a bionic eye.
The Argus II retinal prosthesis system, in a sense, restores vision to the blind.
The patient would wear glasses, not unlike the ones in Star Trek, with a camera attached. The glasses are connected to a video processor, which is then connected to a chip implanted in the eye. The camera “sees” for the wearer, and the video processors converts the image to electrical signals which then go to the brain.
That treats advanced patients of retinitis pigmentosa (RP), a genetic eye disease where the light sensing cells in the retina are damaged, explains Stephen Tsang, an assistant professor of ophthalmology at Columbia University who studies RP.
“So if you think of the eye like a TV, the ganglion cells are like the cable of a TV. If you think of the eye like a camera, you can think of the light sensing neurons are like the film,” Tsang says. “So when the film (the light sensing neurons) dies away in retinitis pigmentosa, the strategy for the Argus II is to bypass the light sensing neuron and stimulate the ganglion cells (the cable of the eye) directly.”
Advanced RP patients can only see whether or not there’s light, but with the implant, they’d be able to make out shapes and edges in black and white. If normal color vision is a high definition TV, then this would be a black and white TV with only 60 pixels.
The implant on the retina has six electrodes across and ten down, says Jennifer Lim, the director of retinal services at the University of Illinois Hospital who will be leading the surgical team. Hence the 60 pixels.
“It’s not going to be vision like you and I have, where we see colors and shapes and images,” she says. “It’s more of a pixelated type vision that they see, but it’s really a great scientific advancement, and almost something out of Star Trek.”
The Food and Drug Administration approved the Argus II this February. The University of Illinois Hospital is one of 12 hospitals nationwide running a Phase Four clinical trial. That means the device has been approved for the market, and researchers will investigate possible long term side effects.
The implant does have side effects. Doctors need to cut open the eye to implant the chip on the retina, so the wound could split or become inflamed, for instance. Lim says such side effects are not uncommon in retinal surgeries and can be treated. She says what’s more important to know is that patients will need to spend five to ten hours learning how to use the device, as well as receive training. After all, they’re learning to see again.
Although the Argus II is limited to treating RP patients, the goal is to extend it to other eye disorders that damage the retina, says Rohit Varma, professor and head of ophthalmology at the University of Illinois at Chicago College of Medicine.
“We’re in a very exciting time in vision research,” Varma says. “We, for the first time, have the ability to give some vision back to people who ordinarily would be blind for the rest of their lives.”
For instance, he says a similar device could treat macular degeneration, a far more common eye disease that is the leading cause of blindness in Americans over 60.
In RP, the patient loses peripheral vision slowly, developing a type of tunnel vision before becoming blind. In macular degeneration, the retina is damaged at its center, which is the most light sensitive. The Argus II has 60 electrodes, and Varma proposes an implant with 240 electrodes or more, placed at the center of the retina, to treat macular degeneration.
“It’s a little way away from that,” he says. “We’re excited at this point that we even have this technology and that we can bring light to people whose lives are essentially dark.”
Stephen Tsang of Columbia University believes that in the near future, advanced patients will be treated with prostheses, but earlier stage patients can receive gene and stem cell therapies. He says researchers are developing such treatments for retinal diseases, citing progress at the University of California, Irvine, University College London and Japan. He says this model of stage-based treatment will also likely be used in treating degenerative brain diseases, such as Alzheimer’s and Parkinson’s.
“The progress is tremendous,” Tsang says. “For example, diagnosing RP patients before they’re born in the earlier stage is not even practical just a few years ago, because it took $3 billion dollars and a few years to sequence one person’s genome. But now it takes only one month and less than $5,000.”