Bionic Eye
A/Prof Chris Williams
Principal Investigator
Research Fellows
Dr James Fallon
Dr David Nayagam
Dr Mohit Shivdasani
Research Assistants
Alexia Freemantle
Rebecca Argent
Prof Robert Shepherd
Principal Investigator
Mark Harrison
Research Engineer
PhD Students
Rosemary Cicione
Sam E. John
Joel Villalobos
We are developing a "wide view" format bionic eye implant, which covers a wide area over the back of the retina resulting in a large central field of vision.
For blind and vision impaired people such as those with the condition retinitis pigmentosa this will mean they are able to negotiate daily tasks independently and safely.
This implant is made of soft biocompatible materials similar to a disposable contact lens.
The following pre-clinical studies are progressing successfully, with human trials to follow.
This research is part of Bionic Vision Australia a collaboration between
the Bionic Ear Institute,
the Centre for Eye Research Australia,
NICTA,
the University of Melbourne and the University of New South Wales.
A new surgical appproach for implanting a bionic eye
Location of bionic eye implant
Histological section showing the layers of the eye and demontrating three potential electrode placement
positions for a bionic eye.
LEFT - blue layer = sclera
MIDDLE - white/maroon layer = choroid
RIGHT - pink/maroon layer = retina
We have selected the supra-choroidal space as the best balance between the safety and effectiveness
of the implant.
An important aspect of our bionic eye research is the development of surgical techniques to implant the device and ensure that it remains in a fixed place.
Several surgical approaches have been proposed for placement of an electrode array for a retinal prostheses; for example epiretinal electrode arrays placed directly on the inner surface of the retina, sub-retinal arrays placed between the retinal layers, and scleral arrays placed on the outer surface (sclera) of the eye. Each of these approaches has potential advantages and inherent safety issues.
Recently, implantation of electrode arrays on the surface of the choroid, the blood vessel network of the eye, has shown promise in that there is a natural cleavage plane between the sclera and choroid that can provide a pocket to hold the electrodes in a stable geometry behind the retina (supra-choroidal placement). A new surgical approach for implanting a bionic eye has been developed, and the safety and reproducibility of this supra-choroidal approach is being evaluated.
Optimised electrical stimulation for a bionic eye that is safe and effective
The aim of this study is to determine if electrical stimulation of a retinal prosthesis (bionic eye) placed on the surface of the choroid behind the retina (supra-choroidal space) is safe and effective.
We are testing how much electrical stimulation of the retina is required to activate the primary visual cortex in the brain and how this relates to the size of the electrodes
Our results have significant implications for the optimal design of supra-choroidal retinal prostheses.
- We have been able to successfully activate the visual cortex through electrical stimulation, with thresholds well below previously established safety limits for platinum electrodes.
- We have discovered the electrode area can have a significant impact on thresholds required for cortical activation in the brain. Larger electrodes require less power to activate the retina compared to smaller electrodes; therefore the implant array design will have to balance high spatial resolution and power efficient activation.
'Wide view' electrode array
This array stimlates an extended area of the
visual field
to help with navigation.
Images can be efficiently created by sequentially
stimulating lines of electrodes.
A new high resolution switch array for a bionic eye
To create useful bionic vision:
- New high-resolution stimulation techniques for the bionic eye electrodes are needed to generate images
- Measuring the resistance in the electrode materials and eye tissue to electrical current (impedance) plays a vital role in understanding the functional ability of the stimulation electrodes.
We are developing a high resolution stimulator and an automated impedance measurement system to address both of these requirements
This automated system enables mapping of stimulation to large numbers of electrodes plus effective impedance testing and error handling. Monitoring of the instantaneous electrode impedance during stimulation will significantly improve understanding of the electrode tissue interface and can verify proper working of the electrodes.
This approach will be useful for stimulation studies and development of specifications for high-density retinal prostheses. This system can also be used to characterise stimulator compliance limits and detect electrode faults.