Date: 28th September 2020
Millions of people around the world experience vision loss due to some form of optic nerve damage, leading causes are diseases such as glaucoma or by severe trauma. Now researchers have developed a revolutionary, bionic cortical vision device which is being prepared for a world-first human clinical trial.
Damage to the optic nerve prevents signals from the retina being relayed to the visual cortex of the brain. There are many causes of optic nerve damage but the most prevalent, glaucoma, is estimated to account for 60 million cases of people experiencing vision loss worldwide. Now scientists from Monash University, Melbourne, are preparing a bionic vision system, Gennaris, for human clinical trials following a successful long-term pre-clinical trial in sheep.
So how does the bionic technology work?
Cortical vision prostheses aim to restore vision by delivering electrical stimulation to the visual cortex. The Monash team’s system comprises of custom-designed headgear which holds a camera and wireless transmitter, a vision processor unit and software, and a set of tiles (9x9mm) that are implanted into the brain.
The video camera captures the surrounding scene, which is sent to the vision processor, here it is processed to extract the most relevant information. This data is then wirelessly transmitted to the circuitry within each of the 9 implanted tiles, which converts the data into a pattern of electrical pulses, stimulating the brain via hair-thin microelectrodes.
Gennaris creates a visual pattern from combinations of up to 172 spots of light (phosphenes) and should allow individuals to navigate indoor and outdoor environments, and recognise the presence of people and objects around them.
Pre-clinical trials
The translation of Gennaris to clinical trials has been driven by the recent success of the bionic system to safely electronically stimulate the brain of sheep.
In this study, ten arrays (7 active, 3 passive) were implanted in three sheep brains using a pneumatic insertor, a purpose built insertion system. Stimulation was delivered through seven of these devices for up to 3 months, accounting to over 2700 hours of stimulation.
Histological analysis showed that the devices and implantation procedure were well tolerated by the brain, visible behavioural issues or seizures resulting from the stimulation were not observed. The study represented one of the first long-term tests of a fully implantable cortical vision prosthesis. The team showed that long-term stimulation was viable without induction of widespread tissue damage.
Conclusion and future applications:
The team have shown that the bionic vision technology has the potential to restore vision for millions of people that are clinically blind, and can be tolerated long-term. Gennaris is currently being prepared for a world-first human clinical trial in Melbourne.
Bionic technology is accelerating the chances of restoring vision and creating it, and offers a giant leap forward in the field. Whilst here, the technology utilises a camera as the visual input, others are trying to mimic the eye as a whole integrated system.
We reported back in May, the creation of a biomimetic bionic eye, consisting of a metal shell at the front, an artificial retina at the back and an ionic liquid interior: dubbed EC-EYE – short for ‘ElectroChemical EYE’. However, this proof-of-concept eye is still at an early stage of development and requires many more advancements before it is clinic-ready. Furthermore, as it would need to be wired into the optic nerve this may eliminate its use in diseases that damage the nerve. Gennaris bypasses the optic nerve - offering an alternative solution for those patients with limited optic nerve function.
The Monash Vision Group (MVG), the collaborative partnership between Monash University and Alfred Health, are now looking to secure further funding, and hope to commercialise the bionic vision technology allowing the scale of manufacturing required for human trials.
Beyond the eye, this technology is also showing promise to improve health outcomes for patient with untreatable neurological conditions such as limb paralysis. The team are also looking into using the technology to moderate epilepsy and depression, or for brain-controlled prosthetics.
For more information please see the press release from Monash University
Rosenfeld, J. V., Y. T. Wong, E. Yan, J. Szlawski, A. Mohan, J. Clark, M. Rosa and A. Lowery (2020). “Tissue response to a chronically implantable wireless, intracortical visual prosthesis (Gennaris array).” Journal of Neural Engineering.
https://doi.org/10.1088/1741-2552/ab9e1c
