Jeanette Pritchard slides a brain onto the table and points to the area where scientists will implant 600 tiny electrodes to produce bionic vision.
The wobbly white organ is a silicon replica of the human one a 60-strong team of researchers at Melbourne’s Monash University is trying to rewire, sending electrical impulses directly to the region creating visual percepts -- the brain’s interpretation of the nerve signals it would receive from a functioning eye. Their device will be tested in animals later this year before the first human studies in 2014.
Across town, doctors at the University of Melbourne are taking a different tack, developing an implant to sit at the rear of the eye and do the work for damaged retinas. Both groups are in a race to capture the market for bionic vision, offering hope to the world’s 285 million blind or partially sighted people. The Melbourne teams may have an edge: expertise in stimulating the brain in the city that produced the top-selling bionic ear and made a $4 billion company of maker Cochlear Ltd.
“As far as we’re aware, we’re at around similar stages to all of the other groups -- certainly not too far behind and, if anything, a little bit ahead,” said Pritchard, Monash Vision Group’s general manager.
No Steve Austin
Almost four decades after bionic implants created the fictional Six Million Dollar Man, scientists are far from being able to replicate a fully functioning human eye, let alone the one with zoom and infrared capabilities of Steve Austin, Lee Majors’ character in the 1970s television show. The most advanced attempts have produced pixilated images in monochrome.
Besides the two groups in Melbourne, Second Sight Medical Products Inc., based in Sylmar, California, and Retina Implant AG, based in Reutlingen, Germany, are among as many as 20 groups worldwide trying to reproduce vision that’s closer to that enjoyed by sighted people. Most research utilizes retinal implants, relying on still-functioning components of the visual sensory system, including the optical nerve.
By acting directly on the brain, Monash Vision’s device will counter all causes of blindness, except those resulting from damage to the visual cortex -- where the percepts are formed. The group devised the approach three years ago for the project, which has a budget of about A$15 million ($15 million).
It entails surgically implanting more than a dozen 8 millimeter-square tiles -- each about a quarter of the size of a thumbnail -- into the visual cortex, located at the back of the brain. Each tile contains 45 electrodes that will penetrate about 2 millimeters into the surface of the brain.
The tiles also contain a microchip and wireless receiver to convey signals delivered from a mobile phone-sized computer that relays compressed visual data from a camera worn by the user. The device will have modes for navigation, detecting people and gauging the proximity of objects, said Arthur Lowery, director of Monash Vision Group.
‘In the Race’
Researchers are testing the tiles in animals for safety and biocompatibility and are studying their function in rats, said Jeffrey Rosenfeld, head of neurosurgery at the Alfred Hospital in Melbourne, who will lead the team implanting the Monash device. Studies in primates will start later this year, he said.
“We’re in the race and are confident we’ll produce a commercial device,” Rosenfeld said in an interview. “Whether it will be as successful as the Cochlear device, who knows. It’s at the forefront of Australian technological design, but it’s also at the world’s forefront of new technology.”
Even among the groups developing bionic prostheses for the retina, there are differences in approaches. The team at the University of Melbourne, known as Bionic Vision Australia, has implanted its device behind the eye in an area known as the super-choroidal space. Their prototype, carrying 24 electrodes on a thin silicon sheet, has been put in three patients with retinitis pigmentosa, an inherited condition affecting about 1 in 4,000 people in the U.S.
The first recipient, Dianne Ashworth, described seeing flashes of light when the electrodes were stimulated by a computer connected to a wire attachment behind her ear.
“It was amazing,” Ashworth said in an Aug. 30 statement. “Every time there was stimulation, there was a different shape that appeared in front of my eye.”
Ashworth’s response to the stimulation was “vital,” said Penny Allen, who led a surgical team implanting the prototype at the Royal Victorian Eye and Ear Hospital.
“The fact we are getting visual stimulation from the device in that position means that we are right in our assumption,” Allen said. “We believe it will be stable there long term, and that’s very important in any prosthesis.”
Ashworth’s surgery took four and a half hours. It involved removing some muscle around the eye so the eyeball could be rolled over and the device placed behind the retina. Once fitted, the muscle was stitched back on. The third surgery took just over three hours, indicating the technique may be less taxing than some approaches that have taken as long as 12 hours, she said.
Researchers will work with the recipients over the next 12 months to determine exactly what they perceive each time the retina is stimulated. They’re looking for consistency of shapes, brightness, size and location of flashes to determine how the brain interprets the information, said Rob Shepherd, director of the Bionics Institute, which designed, built and tested the early prototype.
The next stage of development will incorporate an external camera from which messages will be sent to the device behind the eye. The scientists aim to produce a wide-view implant with 98 electrodes, producing vision with about as many pixels, and a high-acuity model with 1,024 electrodes that might enable users to read large-font text, Shepherd said. By early 2016, he expects the devices to be used in a large-scale patient study.
“All these patients really want is facial recognition,” he said. “That’s potentially possible with a high-resolution device.” A more achievable target is a device that enhances mobility, enabling users to “walk through doors, see large objects,” he said.
Shepherd, who is also professor of medical bionics at the University of Melbourne, was a member of the team that developed the Cochlear implant in the 1970s. At the time, scientists weren’t aware of the brain’s ability to reorganize its neural pathways in response to the hearing device, so amplifying its benefit, he said.
“We called it an aid to lip-reading,” Shepherd said. “But now, children as young as six months are using them and people are using them with mobile phones and in noisy environments.”
Second Sight, co-founded by rival cochlear implant pioneer Alfred E. Mann, began selling its Argus II device in Europe in October. Some patients have been using the implant for more than five years, said Brian Mech, vice-president of business development.
The device typically takes 2-3 hours to fit, with users able to detect faces -- though not recognize them -- and read large-text font, he said in an e-mail. “Most significant gains are in the areas of orientation and mobility,” he said.
Another approach is used by Retina Implant, whose device has 1,500 electrodes that convert light entering the eye into electrical energy, relying on intact nerves inside the retina to relay information via the optical nerve to the brain.
It takes about 8 hours to fit the implant, which lets users identify and locate objects like beer glasses, cutlery or bananas, Walter Wrobel, the company’s chief executive officer, said via e-mail. Users can also read 4-5 centimeter letters from a distance of about half a meter, he said.
While the teams in Melbourne are playing catch-up with more advanced products, it’s not a prospect that fazes Allen.
“If we have a surgical procedure that is safe and readily reproducible, then you don’t really need to be first,” she said. “You actually want to be better.”