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article imageBionic vision research progressing rapidly around the world Special

By Kimberley Pollock     Apr 3, 2011 in Science
The race to deliver an effective bionic eye is alive and well with researchers in Australia, the U.S. and Germany reaching important milestones and undertaking patient trials.
In late March, an Australian research consortium unveiled a tiny microchip which is expected to power a bionic eye. Associate Professor Gregg Suaning, of the Graduate School of Biomedical Engineering at the University of New South Wales and a project leader in the national bionic eye consortium, Bionic Vision Australia (BVA), says the new, microchip has 98 precisely-controlled stimulation channels and numerous features that allow for the delivery of electrical stimulation that can restore some sense of vision.
“At only five square millimeters, the device is tiny but represents a significant advance in nerve stimulation technology. The design team incorporated never-before attempted features with this design and they absolutely nailed every aspect. The result is mind boggling,” Associate Professor Suaning said.
The BVA website explains how the bionic eye works:
The wide-view bionic eye consists of a camera, attached to a pair of glasses, which captures images and sends them to a body-worn processing unit. A wireless transmitter feeds the data and power from this unit to a microchip in the retinal implant. The microchip decodes this information and drives the electrical stimulation in the retina. These signals are then passed along the optic nerve to the brain where they are interpreted as vision.
In a media release, BVA say preclinical studies of their bionic vision system are currently underway and that a safe surgical technique has been developed for implantation.
"Clinicians are now screening people with retinitis pigmentosa to develop a selection protocol for the first group of patients who will participate in tests of the device. Researchers will continue working with patients in the lead up to the first implant of the full system, due by 2013."
In this first phase it is expected that someone implanted with the chip will have their vision enhanced enough to be able to move around and see obstacles. Development is also underway for a second prototype called 'the high-acuity device.' This device will include an implanted chip with over 1,000 electrodes to stimulate the retina and may enable patients to perceive more detailed visual information such as faces and large print. If all goes to plan, the high-acuity device should be ready for testing in 2014.
BVA is not the first to develop a viable bionic eye prototype. Last month, Los Angeles-based Second Sight Medical Products (SSMP) became the first company granted a commercial licence to sell its bionic eye, Argus II, in the European Union. SSMP is currently in trials with this second-generation device at more than a dozen trial sites in the United States, Mexico and Europe (over 30 subjects in total) and have been implanting such devices in humans since 2002.
The Argus II is an implantable device and works in a similar way to the BVA system. It converts video images captured from a miniature camera, housed in the patient’s glasses, into a series of small electrical pulses that are transmitted wirelessly to an array of electrodes implanted on the retina. These pulses then stimulate the retina’s remaining cells resulting in the corresponding perception of patterns of light in the brain.
In a SSMP media release, Dr. Lyndon da Cruz, MD PhD Consultant Retinal Surgeon at Moorfields Eye Hospital in London, UK praised the Argus II. She said, “The fact that nearly all patients had a stable, safe and functioning system and that a majority of patients could recognize large letters, locate the position of objects and the best could read short words impressed us beyond our most optimistic expectations."
According to The Australian newspaper, the SSMP bionic eye will sell in Europe for $US100,000, with operation costs to implant it of $US10,000 to $US15,000.
There is also a third country in the race to develop bionic vision. The German technology company, Retina Implant AG, has also developed a bionic eye implant. Their device consists of an electronic plate just three millimeters square, which is coated with 1,500 light-sensitive sensors. Each sensor triggers an electronic pulse that stimulates nerves that lead to the brain.
The German implant has already been successfully tested in Germany, where it allowed patients to read letters and recognise objects. UK trials of the German device are now underway.
I asked Veronika Gouskova, BVA's Marketing and Communication Manager, about the differences between the various bionic vision systems. She said, while they are similar in concept, there were some technical differences such as the amount of electrodes on the implants. The current SSMP implant has 60 electrodes with their next prototype having 240 electrodes. The first phase BVA implant will have 98 electrodes and their next generation high acuity device will have 1000 electrodes. In theory, the more electrodes on the implant, the better the vision definition but Veronica says that this still needs further research to prove that it is effective in practice.
The Retina Implant AG website says the advantages of their system are that the chip moves with the eye, it has even more light sensitive sensors(1500) and that no spectacles are necessary.
Ms Gouskova said that another difference between the systems may be the longevity of the device. BVA were aiming for "life-time placement." The Retina Implant AG website says that their "medical device will have a life expectancy of several years."
Ms Gouvaska also said that, the cost of the BVA device is expected to be comparable to other medical devices currently on the market, such as the cochlear implant (around US$50,000 for the device, procedure and follow-up care). She highlighted that BVA were working with regulatory authorities and governments to ensure that there would be appropriate subsidies to make the bionic eye more affordable.
To be a candidate for all of the bionic vision devices, patients need to have a functional visual pathway from the retina to the brain along the optic nerve, as well as some intact retinal cells. As such, the current systems are aimed at people who have experienced vision loss due to retinitis pigmentosa (RP) and age-related macular degeneration (AMD).
RP affects 1.5 million people around the world, while AMD affects one in seven people over the age of 50 and is the leading cause of blindness and vision loss in Australia.
More about Bionic eye, Eyesight, vision impaired, Blind, Microchip
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