Bionic eye solution for visual blindness

The FDA has approved Argus II, manufactured by Second Sight Medical Products, to treat people with severe retinitis pigmentosa, a group of inherited conditions in which photoreceptor cells, which absorb light, break down.

The first version of the implant had a sheet of 16 electrodes, but the current version has 60. A tiny camera mounted on glasses captures images, and the video processor, worn on the belt, translates these images into pixelated patterns of light and dark. The processor transmits these signals to the electrodes, which send them along the optic nerve to the brain.

About 100,000 Americans have retinitis pigmentosa, but initially between 10,000 and 15,000 will likely qualify for Argus II, according to the company. The FDA says up to 4,000 people a year can be treated with the device. This number represents people over the age of 25, who once had useful vision, who show signs of an intact inner retinal layer, who have very limited light perception in the retina at best, and who are so visually impaired. that the device would prove to be an improvement. Second Sight will begin making Argus II available later this year.

But experts said the technology holds promise for other blind people, especially those with advanced age-related macular degeneration, the leading cause of vision loss in the elderly, affecting an estimated 2 million Americans. . About 50,000 of them are currently badly enough that the artificial retina is useful, said Dr Robert Greenberg, President and CEO of Second Sight.

In Europe, Argus II received approval in 2011 to treat a larger group of people, those suffering from severe blindness caused by any type of external retinal degeneration, not just retinitis pigmentosa, although it is not currently marketed in Europe only for this ailment. In the United States, additional clinical trials must be completed before the company can seek broader FDA approval.

Ultimately, Dr Greenberg said, the plan is to implant electrodes not in the eye but directly into the visual cortex of the brain.

“It would allow us to fight blindness from all causes,” he said.

Initially, the artificial retina will be available in seven hospitals in five states: New York, California, Texas, Maryland and Pennsylvania. It will cost around $ 150,000, not including surgery and training sessions to use the device. Second Sight said he was optimistic the insurance would cover him.

Developed over 20 years by Dr. Mark S. Humayun, ophthalmologist and biomedical engineer at the Doheny Retinal Institute at the University of Southern California, the artificial retina was inspired by cochlear implants for the deaf. Some of the funding came from a cochlear implant manufacturer and other private sources, but around US $ 100 million was provided by the National Eye Institute, the National Science Foundation, and the Department of Energy, all federal agencies. .

Dr Humayun said he plans to apply the technology to conditions other than blindness, implanting electrodes in other parts of the body to treat bladder control issues, possibly, or bladder control. spinal palsy.

“We don’t think of the human body as an electrical network, but it works with the help of electrical impulses,” he said.

The Argus II had relatively few safety concerns, mainly post-surgical infections and occasional thin layer erosion in the eye that covered the implant. These issues were resolved, Dr Greenberg said, and only two people needed to remove the implant. An FDA advisory group voted unanimously in September to recommend approval, believing the benefits outweighed the risks.

Some patients improve more than others for reasons that the company has not been able to determine. Kathy Blake of Fountain Valley, Calif., Said she was successful with a Second Sight exercise to see if patients can identify large numbers or letters on a computer screen.

Dean Lloyd, a lawyer from Palo Alto, Calif., Said he first asked, “Is this really worth the time and expense? At first, I didn’t think so.” At first only nine electrodes worked, but over time his implant has been adjusted so that more electrodes respond, and now 52 of them are working. He can see flashes of color, which not all patients can see, and he wears the glasses and the video processor all the time.

“If I don’t wear it, it’s like I don’t have my pants on,” he said. “I even fell asleep with the blooming thing.”

Stephen Rose, research director of the Foundation Fighting Blindness, which supported Dr Humayun’s very early work but has not funded it since, said the artificial retina would ultimately be just one of the options to help blind people.

“I think there are huge possibilities,” he said. “I’m not minimizing the importance of the retinal prosthesis; don’t get me wrong. It’s huge for some people, and it’s here now.”

Barbara Campbell, 59, relishes how the device helps her navigate the streets of Manhattan, locate her bus stop and spot the light in her apartment building’s lobby when she’s in a cab.

Most exciting, however, is how it enhances his museum, theater, and concert experience.

During a performance of Rod Stewart, “I could really see his hair,” she said, which was white blonde under the lights. At a Diana Ross concert, although Ms Campbell was sitting away from the stage, she said Ross was “wearing a sparkly outfit and I could see her”.

Bad luck for a performance by James Taylor, however. Her sober clothes created no contrast that the artificial retina could register. Alas, Ms Campbell said: “He was not that brilliant.”

The New York Times


Source link

Comments are closed.