It’s an exciting time in the world of bionic retinas, which are enabling people with blinding retinal diseases to perceive patterns of light. This, in turn, allows them to interpret basic shapes and objects, thereby improving their mobility and independence. Second Sight’s Argus II is available in the United States and Europe, and Retina Implant AG’s Alpha IMS is also on the market in Europe. Many research groups around the world are developing devices as well.
One of those is Bionic Vision Australia (BVA), a research consortium which recently completed the first human study of its innovative bionic retina technology. I recently interviewed Anthony Burkitt, a professor of engineering at the University of Melbourne and director of BVA, about the consortium’s work. Below are highlights from our conversation:
What got Australian researchers interested in bionic retinas?
I worked for many years with cochlear implants for providing hearing to deaf people. They were originally developed in Australia, and today, about 300,000 people around the world use them. Recognizing they were a mature and reliable technology, a group of us got together and explored how the technology could be used in other areas.
One application that really stood out was blindness, particularly when caused by degenerative eye diseases. We invested significant time and effort into miniaturizing the technology so it could work within the confines of the eye’s anatomy to stimulate surviving nerve cells.
We put together a proposal and received funding from the Australian Research Council, an agency of the Australian government. We received $42 million in funding and launched our consortium in 2010.
What were the results of the human study of your bionic retina?
The study enrolled three patients who are blind from retinitis pigmentosa (RP), an inherited disease in which the light-sensitive retina at the back of the eye progressively degenerates. The patients would typically come in one day a week and move around in the lab environment. We ran numerous tests to determine how they would use the implant in their everyday lives.
First, they identified shapes on a computer screen, and then were able to recognize letters and simple words. We also had them perform simple mobility tasks. That’s where we really see the benefits of this technology—to enable patients to move around and to see and avoid obstacles in their environment. For example, to recognize a chair or door, or see what’s on a table.
How does the device work?
The patient wears glasses, which have a camera that sends images to a processor that electrically stimulates an array of electrodes implanted in an area near the retina called the choroid. As an early prototype, we’re using a small number of electrodes, 22. The electrodes are like pixels to the user.
The reason for putting our first device in the suprachoroidal space is that it appears to be a safe and mechanically stable place for the electrode array. Our surgeons have developed a simple procedure to create a pocket to slide the electrode array in, and it stays there quite safely.
What are your next steps?
In the next phase, we’ll have a device with 44 electrodes. The trial is scheduled to begin in the first half of 2015. It will include three RP patients and run for 12 to 18 months. Patients will take the device home and use it in their everyday lives.
Based on what we know from cochlear implants, we believe these devices have the potential to be very useful, because the brain learns to interpret the signals it’s getting. The more often patients use it, the more benefit they derive. We’re really keen to see what benefits the patient can get from the 44-electrode version. We also have a 98-electrode version in development.
We have another technology in pre-clinical testing that uses diamond-carbon materials— compared to silicon and platinum, which we and most other groups are working with. This high-acuity device, which will have 256 electrodes, has the potential to provide central vision to enable people to do things like read large print and recognize faces. We have a way to go, but it will be interesting over the next couple of years to see how it plays out.
The big challenge for any implanted device is using materials that are safe for the lifetime of the patient. Everything has to be hermetically encapsulated so the body is protected from and doesn’t damage the electronics. Diamonds are essentially carbon and very well tolerated by the body. We just need to see if we can get the visual outcomes the patients want.
Pictured, above: a participant in the BVA human study. Photo courtesy of Bionic Vision Australia.