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Tuesday / March 5.
HomemistoryThe Race for Sparkling Vision

The Race for Sparkling Vision

Diamonds could become the best friend of visually impaired people around the world. Researchers at Bionic Vision Australia plan to take advantage of these precious gems in the development of Australia’s first bionic eye.

Scientists around the world are rushing to develop a bionic eye that may one day enable blind people, especially those with disorders like Retinitis Pigmentosa (RP) and Age Related Macular Degeneration (AMD), to see again.

Prototypes are already in use overseas and whilst these devices are highly experimental, they are important early contributors to what will undoubtedly be a field of medical treatment that will make great advances in the future.

Bionics is a form of bio-mimicry – the practice of applying methods and systems observed in nature to modern technology. A good example of a bionic device is the artificial cardiac pacemaker which mimics the natural cardiac pacemaker by generating electrical impulses.

We made a diamond device so the implant inside the eye will not deteriorate or will not be damaged by any other means

One new bionic eye procedure, developed in Germany, could be on the market in five years. The procedure, which has been developed by Retinal Implant AG, in Tuebingen, is ‘sub retinal’ meaning that surgeons lift up the retina and place the electrode array beneath it. The device relies on the eye itself to transmit images.

The microchip performs the work of the retina, processing light and sending signals to the optic nerve and finally to the brain. It enables patients to see black and white images again.

The German device has been tested successfully on seven people and at this stage, it is expected to be approved for commercialisation in five to seven years. However, before this can occur, the device must go through studies into efficacy and safety. Meanwhile, larger studies are underway by Second Sight LLC of California who have already implanted around 50 people world-wide.

Research in Australia

Australia’s first prototype bionic eye was unveiled in March last year by Bionic Vision Australia (BVA), a national consortium of researchers working together.

The technology consists of a camera, attached to a pair of glasses, which captures the visual scene and transmits radio frequency signals via an external processing unit to a microchip implanted at the back of the eye. This is similar to the German technology. However, whereas the German device is sub retinal, the Australian device is ‘supra choroidal,’ meaning the electrode array is implanted just beneath the white part of the eye.

One of BVA’s Chief Investigators, Associate Professor Gregg Suaning says the advantage of the Australian approach is that it vastly simplifies the required surgical procedure. However, the result is that the device is less close to the nerve cells we aim to stimulate. “It remains to be discovered if this placement is better, worse or the same in terms of patient benefit.

Differing Electrodes

Another difference is the number of electrodes being used to stimulate the retina. Whereas the German chip uses 1,500 electrodes, BVA’s first prototype retinal prosthesis, the wide-view neurostimulator device, will use an implanted chip with 100 electrodes. The Australian research group’s second prototype, referred to as the high-acuity device aims to produce over 1,000 electrodes.

A/Prof. Suaning says that while a greater number of electrodes will increase opportunities for the stimulation of nerves, the resulting improvement in visual acuity is not necessarily directly proportionate. “This is because it is quite likely that when the electrodes are closely placed, the electric fields will overlap and excite the same nerve cells,” he said.

“It is true that the German device from Retina Implant AG contains 1,500 ‘photodiodes’ and electrodes, but this does not necessarily mean that a patient fitted with such a device can ‘see’ 1,500 individual dots,” said A/Prof. Suaning.

“Not to detract from the amazing achievement the group from Tuebingen has made… The electrodes appear to be acting in clusters rather than individually. This means that while there are indeed 1,500 electrodes, the patient is likely to see far fewer dots than 1,500.”

In the case of the Australian devices, A/Prof. Suaning said, the wide-view device has 100 channels of stimulation, each separated by about one half of a millimetre. “Because of the way the electric fields form, it is more likely that individual electrodes will produce individual perceptions because the separation between electrodes is so large. This, we hope, will be a tremendous aid to navigation in unfamiliar environments.

“In the ‘high-acuity’ device, the BVA researchers aim to produce 1,000 electrodes (32 rows x 32 columns of electrodes). Depending upon the separation distance of these electrodes, and the electric fields they produce, the same conditions and same concerns of overlap may apply as in the case of the German device – but we don’t know for sure, and will discover more on this subject in the years to come.”

Diamond Technology

While the German device is manufactured from metal, the Australian high-acuity device will use diamonds, which appear to offer greater longevity.

Dr. Kumar Ganesan, a physicist at the University of Melbourne helping to design the second prototype bionic eye for Bionic Vision Australia, said: “We made a diamond device so the implant inside the eye will not deteriorate or will not be damaged by any other means.”

A/Prof. Suaning says the use of diamonds in biomedical applications looks promising. “We are only now learning about the benefits of diamonds in biomedical applications. So far things look promising in terms of compatibility with the body and good progress is being made in terms of the diamonds becoming electrical conductors.

“There is, however, some way to go before we will see a bionic eye produced with diamonds. In the meantime, we are working with laser-micromachined ceramics and platinum to form our wide-view device, which will become the first device implanted by the BVA. The Tuebingen (German) device attracts some concerns about longevity within the body – particularly their electronics which are effectively immersed in a corrosive, salt-water environment – but so far they’re working far better than I (or perhaps anyone) anticipated. What they have achieved is very exciting.”

Patient Benefits

While the bionic eye technologies currently under development will not enable patients to see images in colour, it will deliver life changing vision for recipients.

Australia’s wide-view device aims to provide patients with the ability to contrast light from dark, and as a result, to manoeuvre around large objects such as buildings, cars and park benches. This will enable greater independence. BVA claims this device may be most suitable for patients with retinitis pigmentosa. First tests with patients are scheduled to begin by 2013 and, subject to successful completion, the commercial development process should commence shortly after.

The group’s high-acuity neuro-stimulator device aims to allow patients to perceive more detailed visual information. According to BVA, patients with the high-acuity device may be able to recognise faces and read large print somewhere between the second and third line of a Snellen chart. This device, which they expect will be most suitable to patients with age-related macular degeneration, should be ready for the first tests with patients in 2014.

Research is underway around the world focussing on delivering the existing technology for black and white vision to the market as soon as possible. Some groups are looking into the possibility of colour vision technologies, but this will take many more years of development.

Training and Patience

According to BVA, a person using a retinal implant to see won’t experience vision in the same way that a person with a healthy eye does. It will be quite basic to start with and they will need some training to adapt to the implant. However, with time, training and patience, people will be able to use this visual information so they can be more independent and mobile.

Rods and Cones

Many people who are blind – or going blind – are so because of malfunctioning rods and cones that make up the light sensitive layer of the retina.

These rods and cones help to convert light into electrical impulses, which travel through the optic nerve to a specific area in the brain where images are formed. Any degeneration of these cells or disease of the optic nerve and brain can result in the loss of vision.