Being able to sort white washing from coloured washing might not mean much to most people, but for one patient enrolled in a Centre for Eye Research Australia (CERA) study, it was a landmark moment: she had gone blind years ago, and being able to tell different colours of washing apart was a sign that the retinal prosthesis she wore had begun to give her back some meaningful sight.
CERA is part of a group of organisations, including the University of New South Wales, the University of Melbourne, the Bionic Institute and others, that have been working on creating what's been called a 'bionic eye', a system that aims to return elements of sight to those with impaired vision.
The bionic eye system has been trialled with seven patients over two phases. All have a condition known as retinitis pigmentosum (RP), an umbrella term for a group of genetic mutations that cause those to inherit them to progressively lose their sight. The condition makes itself known in the teens or early 20s, and within years, leaves those that have it with only the rudiments of sight: able to see a light on or off, but no more than that. They lose the ability to read, to see the faces of friends and family, and to navigate around their home and neighbourhood independently.
It's these losses that the CERA bionic eye hopes to be able to counter. In RP, only the photoreceptor layer of the retina dies off; the other layers of the retina, which contain nerves to help pass along visual information to the brain, remain intact. It's this element of RP that the bionic eye seeks to take advantage of: an electrical array is slid into a space within the back of the eye, and stimulates those neural layers of the retina. The images that the user sees are gathered from a camera attached to a pair of glasses they wear, forwarded onto a visual processing unit which crunches the data and wirelessly transmits it to an implant under the skin on the side of the head. The implant receives the signal, and passes it on to the array, which stimulates the retina and allows the wearer to see patterns.
While CERA's eye isn't the first 'bionic eye' system to be tested in human volunteers, it does offer a more simple surgical approach. "The idea was that if you have a more simple surgical approach, then there are less surgical complications," Penelope Allen, associate professor at CERA and head of the vitreoretinal Unit at The Royal Victorian Eye and Ear Hospital, tells ZDNet. The array sits in a natural pocket within the eye, known as the suprachoridal space, which exists between the retina and the sclera, what most people know as the 'white' of the eye. "The device slides in quite easily and it is held in place quite naturally in that area, we don't need to put a [surgical] tack or go actually inside the vitreous cavity of the eye. It makes it a much more simple and straightforward surgical approach," she says.
With the hardware in place, wearers began testing the system in the lab, learning to interpret the patterns the system transmit as visual information. "Because they have not really had any visual information to interpret for a long time, when the device stimulates the retina, they see small flashes of light. They need to go through lab-based training so that we can determine the level of electrical stimulation that each electrode requires to produce a visual flash of light," says Allen.
First, wearers learn to distinguish edges, then identify doors in a room, and then navigate their way around an obstacle course. Once they're happy with the lab-based tests, wearers use the device outside to find their way around footpaths. From there, wearers take the system to use at home, before finally testing it outdoors.
"The amount that the patients can interpret from the device initially, we were really impressed with what they could do. One of the patients in the prototype trial said as she became much more accustomed to using it, she started to feel like she wasn't using a camera, the vision was just coming from her eye. I think when we went into the 44 channel trial last year, I was quite confident that all of the patients would see something in the lab even though we couldn't tell them that. When they start to do the lab-based training and respond really well, it's really exciting," says Allen.
While the bionic eye doesn't provide vision in the same way that sighted people understand it — "it's more a depiction of edges," says Allen, whereby wearers "can scan over an object and, by scanning and working out its size and possible shape, then possibly identify it" — it does provide enough information for wearers to complete tasks that would have once seemed impossible: sorting washing, walking around without a guide dog, or simply knowing who's speaking in a group conversation.
"Everybody has a different task at home that they would like to do; part of the training at home is identifying those tasks that they would find important, to try to help them do that," Allen says. The system works best in high-contrast environments, but comes with different modes to enhance contrast in other situations: by helping patients find the right mode and continue to refine how those modes work, it's hoped the CERA bionic eye will help more people with sight loss tackle tasks that may once have been impossible.
During the trial, CERA and its partners will be gathering data on how wearers are making use of the system. "Once they've taken the device home, they come in at three monthly intervals to be tested over all the obstacle course again to see if there is improvement in their outcomes and functioning. They do testing at home to see whether those tasks that they want to be able to perform at home, and whether they're able to do that, because we need to have objective evidence the outcomes are better," Allen notes.
While the trial of the bionic eyes is designed to last just two years, the implants could remain in situ over a much longer period. A spinout of the project, Bionic Vision Technologies, has been set up with a view to commercialise the technology over time.
CERA's is not the only bionic eye system currently in testing. Second Sight, for example, is also working on an implantable retina, which has been trialled with individuals with retinitis pigmentosa, while other research efforts are hoping to build systems that bypass the eye entirely and transmit visual messages straight to the brain.
Choosing participants for such research is not without its challenges. The participants had to undergo psychological evaluation, and be prepared for the prosthesis not to work, despite the group's confidence that they would be able to restore some element of vision.
"They're really interesting and a fantastic group of patients to work with. They're very altruistic. Because it's an inherited disease, many have relatives that have the disease, so they're very interested in not only benefits to themselves but benefits for future generations," says Allen.
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