Wednesday, October 15, 2014

ThumbsUp! Toronto hospital implants Canada’s first ‘bionic eye’

Bionic eye implants let Canadian patients perceive light

Sheryl Ubelacker | The Canadian Press
It’s not exactly the bionic eye that gave the Six Million Dollar Man of 1970s TV fame extraordinary vision, but a new implant is helping some people with virtually no sight due to degenerative retinal diseases make more sense out of light and dark images, and it may one day dramatically improve their ability to see.

Doctors at Toronto Western Hospital have implanted the Argus Retinal Prosthesis System in the first two patients as part of a 10-person clinical study, the first such operations performed in Canada.

The device implanted in the eye uses a tiny patch containing 60 electrodes that transfer image impulses to the retinal nerves, which then travel through the main optic nerve to the brain for processing.

The images are sent to the eye through a tiny video camera on the bridge of a special pair of glasses, which are wired to a small battery-operated computer modulator that’s worn outside the body.

“Bionic eye is a good word,” said ophthalmologist-in-chief Dr. Robert Devenyi, who is part of the surgical research team.

“It’s an artificial device that stimulates electronically what normally the body would do … It stimulates the eye directly,” Devenyi said Tuesday of the device, explaining that it bypasses the layer of the eye where receptors called rods and cones normally convert light energy into neuronal signals.

Rods are responsible for vision at low light levels, while cones are reactive at higher light levels, are capable of colour vision and provide high spatial acuity. In patients with retinitis pigmentosa and other degenerative retinal diseases, the rods and cones are missing.

Although vision achieved with the retinal implant is not like regular sight, it does allow the person to perceive patterns of light that the brain can be trained to recognize.

Orly Shamir, who was born with Leber Congenital Amaurosis, received the first implant June 5, and she has already seen improvement in her ability to discern light from dark — something she has not been able to do for the last 10 years.

Shamir, 46, said she had limited vision as a child but was able to read large print and get around unaided. In her mid-20s her vision started to decline gradually, and by her mid-30s she suddenly couldn’t make out sights most of us take for granted — the denomination on paper money, the details of her face in a mirror. Eight years ago she got a guide dog.

“For the last 10 years now, I’ve had only a bit of light perception. There’s no definition, there’s nothing that I can use in order to get by,” Shamir told a media briefing announcing the first two surgeries.

But just three months after the operation, Shamir said she is able to make out white squares that move from place to place on a black computer screen, an exercise that is part of her visual rehabilitation program at Toronto Western.

“I’m still in the beginning stages. Before the surgery I couldn’t find images or movement on the computer screen. There was nothing that I could detect,” she said. “Now I’m able to see movement. I can’t tell the direction, but I can see movement.”

The rehab is meant to retrain her brain to decipher the images she receives through the implant. Part of that process is having a rehab professional come to her Toronto home to help adapt the system for day-to-day activities, such as walking outside and being able to see where grass turns to sidewalk, for instance.

“Or in my kitchen, I’ll be able to see on the counter where there’s a plate or whatever that I’m looking for.”

Shamir said the more she practises, the more she’s able to recognize objects and features around her, even if it is only by identifying certain shapes and textures.

“It’s like starting all over again and one day I might see something I never saw before,” said the married mother of three boys who works as a bank credit analyst. “And it’s like, ‘Oh, wow. I could see this or I could at least know it’s there.'”

One of her most exciting moments came when a rehab specialist showed her a board covered in black and white stripes, and she was able to see them as bands in contrasting shades.

“My next step is to go to the Toronto zoo and find some zebras,” she said, laughing.

Devenyi said Shamir’s ability to see even that “is remarkable,” and he called the eye implant a medical advance he hadn’t expected to see in his lifetime.

Because the computer modulator is external, any software updates or battery recharging can be done without another invasive surgery, he said.

But giving a patient the so-called bionic eye isn’t cheap: the implant alone runs US$144,000, and then there are the costs of the fairly complicated surgery and the visual rehabilitation, he said.

The Argus implant, developed by California-based company Second Sight, is not yet approved for widespread use in Canada, although it has been given the green light by the U.S. FDA. Devenyi expects that Health Canada will soon approve the device, however, and the Toronto Western team plans to approach the Ontario government about funding the implant surgery.

About 35 or 40 implants have been performed in the U.S., he said, noting that most patients have since learned to walk around on their own and are able to identify and reach for objects on a table, for example, without help.

“Some people have even been able to read quite large letters. So it’s petty remarkable.”

Ian Nichols, 76, slowly lost his vision over the years due to retinitis pigmentosa, to the point where he was declared legally blind and had to start using a white cane to get around. For more than 20 years, the now-retired Anglican priest has lived with little light perception and no useful vision.

But what happened two weeks after his Sept. 4 implant surgery has given him a big ray of hope.

When asked to find the white block on the black computer screen during visual rehab, “I scanned (with the video camera) and I reached out and landed right on the square,” said the Toronto resident.

“When I first put my finger on that square, and (the technicians) said ‘Right on!’ that was really exciting and emotional,” he said. “I got a bit choked up about that.”

Devenyi said the Foundation for Fighting Blindness, which helped fund the implants, estimates that 1,000 to 1,500 patients would be candidates for the surgery based on current criteria.

“As the implant improves, as the software improves, that threshold will change dramatically,” he predicted, noting that some researchers are discussing whether the device could help people with macular degeneration in the future.

With software improvements and added functions, “there might be no limits to what we really see.”

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