Summary: A newly designed bionic eye is safe and stable for long-term implantation, researchers conclude following a three-month study in sheep. The discovery paves the way for human trials of the bionic device.
Source: University of Sydney
A bionic eye being developed by a team of biomedical researchers at the University of Sydney and UNSW has shown to be safe and stable for long-term implantation in a three-month study, paving the way towards human trials.
The Phoenix99 Bionic Eye is an implantable system, designed to restore a form of vision to patients living with severe vision impairment and blindness caused by degenerative diseases, such as retinitis pigmentosa. The device has two main components which need to be implanted: a stimulator attached to the eye and a communication module positioned under the skin behind the ear.
Publishing in Biomaterials, the researchers used a sheep model to observe how the body responds and heals when implanted with the device, with the results allowing for further refinement of the surgical procedure. The biomedical research team is now confident the device could be trialed in human patients.
The Phoenix99 Bionic Eye works by stimulating the retina—a thin stack of neurones lining the back of the eye. In healthy eyes, the cells in one of the layers turn incoming light into electrical messages which are sent to the brain. In some retinal diseases, the cells responsible for this crucial conversion degenerate, causing vision impairment. The system bypasses these malfunctioning cells by stimulating the remaining cells directly, effectively tricking the brain into believing that light was sensed.
“Importantly, we found the device has a very low impact on the neurons required to ‘trick’ the brain. There were no unexpected reactions from the tissue around the device and we expect it could safely remain in place for many years,” said Mr Samuel Eggenberger, a biomedical engineer who is completing his doctorate with Head of School of Biomedical Engineering Professor Gregg Suaning.
“Our team is thrilled by this extraordinary result, which gives us confidence to push on towards human trials of the device. We hope that through this technology, people living with profound vision loss from degenerative retinal disorders may be able to regain a useful sense of vision,” said Mr Eggenberger.
Professor Gregg Suaning said the positive results are a significant milestone for the Phoenix99 Bionic Eye.
“This breakthrough comes from combining decades of experience and technological breakthroughs in the field of implantable electronics,” said Professor Suaning.
The team will now apply for ethics approval to perform clinical trials in human patients, as they continue to develop and test advanced stimulation techniques.
How the bionic eye works
A patient is implanted with the Phoenix99. A stimulator is positioned on the eye and a communication module implanted behind the ear.
A very small camera attached to glasses captures the visual scene in front of the wearer. The images are processed into a set of stimulation instructions.
The instructions are sent wirelessly through the skin to the communication module of the prosthesis.
The implant decodes the wireless signal and transfers the instructions to the stimulation module, which delivers electrical impulses to the neurons of the retina.
The electrical impulses, delivered in patterns matching the images recorded by the camera, trigger neurons which forward the messages to the brain, where the signals are interpreted as a vision of the scene.
Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep
Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies result in extensive neural and glial remodelling, with survival of excitable retinal neurons that can be electrically stimulated to elicit visual percepts and restore a form of useful vision. The Phoenix99 Bionic Eye is a fully implantable visual prosthesis, designed to stimulate the retina from the suprachoroidal space.
In the current study, nine passive devices were implanted in an ovine model from two days to three months. The impact of the intervention and implant stability were assessed using indirect ophthalmoscopy, infrared imaging, and optical coherence tomography to establish the safety profile of the surgery and the device.
The biocompatibility of the device was evaluated using histopathological analysis of the tissue surrounding the electrode array, with a focus on the health of the retinal cells required to convey signals to the brain. Appropriate stability of the electrode array was demonstrated, and histological analysis shows that the fibrotic and inflammatory response to the array was mild.
Promising evidence of the safety and potential of the Phoenix99 Bionic Eye to restore a sense of vision to the severely visually impaired was obtained.