xeiss

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xeiss10 karma

We often say among ourselves that these innovations are like something out of a sci-fi! As a kid I would never have believed it possible, let alone be part of the research myself.

Oh and yes, I think a lot of us love sci-fi. It probably inspired many to follow a scientific career. But just to be clear - we're not creating a T-800 here!

xeiss6 karma

(I'm just sneaking back to leave this ITT. This is the text from the above PDF, which I'm about to delete from my dropbox. Thanks again for your great questions reddit! Please feel free to contact us if you have any further questions.)

BACKGROUND

Inception:

In 2009, the Australian government announced a Special Research Initiative directed towards restoring vision. The rationale being that Australian scientists could leverage the considerable knowledge and experience gained from the development of the cochlear implant 30 years earlier, to develop a retinal implant to provide a sense of vision to people with significant vision loss. Hence a consortium was formed, Bionic Vision Australia (BVA), made up of several universities and research institutes distributed across Australia. The members of the consortium are:

With supporting partners:

  • National Vision Research Institute,
  • University of Western Sydney, and
  • Royal Victoran Eye and Ear Hospital

It is truly a multidisciplinary effort with over 130 researchers and 50 graduate students currently working on device design, materials, stimulation/vision processing strategies, safety and efficacy testing, electronics, clinical outcomes, surgical approaches etc . You can read more about BVA here: http://bionicvision.org.au/. There is a glossary here if you are unsure of the meaning of some of the words we use: http://bionicvision.org.au/eye/glossary.

Test participants:

In 2012, Dianne Ashworth, Murray Rowland and Maurice Skehan were implanted with retinal prostheses (that is, “bionic eyes”) in Melbourne, Australia. The device was implanted between the sclera and the choroid layers of the eye, making it a “suprachoroidal” retinal prosthesis. All three people have a condition known as retinitis pigmentosa, which is the most common form of inherited blindness. They all have significant vision loss and have almost no light perception remaining. They volunteered to be research participants in this pioneering scientific study.

Mechanism:

Retinitis pigmentosa leads to a progressive loss of photoreceptors, the specialised cells in the retina responsible for converting light into neural signals. However, other cells of the retina remain functional. An electrode array positioned in the eye close to the remaining relatively healthy retinal cells can directly activate neural responses in the optic nerve through focused electrical stimulation. Because the retina is mapped to the visual space, the patterns of electrical stimulation delivered in the retina are maintained throughout the visual pathways of the brain and are perceived as equivalent patches of light known as ‘phosphenes’. This is the same principle which the cochlear implant (bionic ear) uses to stimulate the auditory pathway in deaf patients. For a recent review of the scientific literature on visual prostheses, if you have a library subscription, you can check out: http://dx.doi.org/10.1016/j.tibtech.2013.07.001

Device:

The device implanted into our three patients was a prototype device, intended to help researchers learn about how the brain interprets information from an implant like this. It is made up of a conformable medical grade silicone carrier with platinum disc-shaped electrodes arranged in a hexagonal grid. A thin platinum cable consisting of 24 wires wrapped in a helix connects the electrode array in the eye to a titanium connector that is fixed to the skull behind the ear. You can see a photo of the device here: https://flic.kr/p/dMchg4

The implant is connected to a laboratory stimulator that provides electrical stimulation to the electrodes in the eye. By activating various combinations of these electrodes, rudimentary patterns can be formed and perceived by the patients, much like pixels on a screen. This video explains the basic principle: https://www.youtube.com/watch?v=yFP7mzrM0Yc

Approach:

It was originally thought that a very large number of small electrodes would be needed to create a high resolution image. However, this has yet to be shown experimentally and there are many technical reasons why this is difficult to do safely – ask us about it if you’re interested. Researchers within BVA are working towards overcoming these hurdles for vision tasks where ‘high-acuity’ is required, such as reading and face recognition. However, our present device is aimed at providing a wide field-of-view implant for navigation purposes, for which high resolution is not required. The suprachoroidal placement is minimally invasive and considered to a safe and stable location for a retinal implant.

Worldwide Effort:

The Australian BVA group is one of several working to provide artificial sight to people who have lost their vision due to conditions such as retinitis pigmentosa. Two other groups (from USA [http://www.2-sight.eu/en/] and Germany [http://retina-implant.de/en/default.aspx]) have recently received regulatory approval to commercialise their devices. These groups use different surgical approaches and different types of implant technology. A Japanese group has also used a similar approach to ours in a couple of patients and there are a handful of other groups around the world currently developing clinical devices. A team at Monash University in Melbourne, which was also funded through the same Australian government initiative, are developing a different technology which aims to provide electrical stimulation directly to the brain. Although all the groups worldwide are engaged in healthy scientific competition, we are all still working towards the same outcome (restoring a sense of vision to those who have lost it) and share our research findings regularly at conferences and in publications. We can discuss the technical differences and the rationale for our design/approach if you are interested.

Study Workflow:

Our current bionic eye device was designed and tested in Melbourne in a range of preclinical studies (2008 – 2012; Bionics Institute). Concurrently we refined the clinical procedures, the surgical approach and selected the patients (Centre for Eye Research Australia). The implants were anatomically fitted for clinical use and manufactured by the Bionics Institute (2011-2012) and following the implant surgeries (2012; Royal Victorian Eye and Ear Hospital), the patients were closely monitored by clinicians in a 24 month clinical trial. Responses to stimulation of the electrodes in the patients’ eyes were extensively tested in psychophysics studies (2012 – 2014). Finally, the patients were fitted with cameras and vision processors, and they were able to undertake basic daily living tasks and navigate obstacles (2014; Centre for Eye Research Australia and National ICT Australia, Canberra). We are now nearing the end of this patient study. The clinical trial is registered here: http://clinicaltrials.gov/show/NCT01603576

Future:

We are now developing next-generation bionic eye implants, the first of which will have double the number of electrodes to the first prosthesis (covering twice the visual field). It will be fully implantable and the patients will be able to take this device out of the laboratory to use at home in their daily lives. The other BVA technology in development and preclinical testing include a suprachoroidal device with 98 stimulating electrodes and a completely novel device with 256-1000 electrodes made from diamond. The Australian government grant (through BVA) will end in December 2014, so we are currently seeking funding to continue our research and commence patient tests with the first of the next generation devices.

Extras:

xeiss4 karma

Thanks for having us reddit! We're excited to answer your questions. We had a feeling that this would be a question that would come up so we've prepared a PDF with some background material. You can download it here: https://www.dropbox.com/s/69o7v9lb0chc23s/20140806%20-%20Bionic%20Vision%20Australia%20-%20reddit%20IAmA%20-%20background%20info.pdf

xeiss3 karma

Essentially, an electrode array is implanted near the patients retina. This electrode array provides electrical stimulation which directly activates their optic nerve - bypassing the damaged photoreceptor. The patterns of stimulation in the eye are derived from a camera/vision processor and are seen as spots of light by the patient. By controlling the pattern of stimulation delivered to the array, we can control the image that the patients perceive.

xeiss2 karma

We are working on upgrades for our next generation device. We are interested in a larger visual field coverage - and how that will help our patients to better navigate. We are also interested in how tracking the patients' eyes and dynamically correcting for these movements will provide more useful visual percepts.

*edit - and of course the device gives us a model for investigating basic visual neuroscience questions in much the same way that cochlear implants have unlocked certain fields of auditory neuroscience research. It will be fascinating how this field develops over the coming years.