In a surprise move, the UK’s National Health Service announced late last year that it was funding a trial in collaboration with Manchester Royal Eye Hospital to fit 10 patients with bionic eyes (Argus II). Such clinical trials speak optimistically about the potential of the technology.The bionic eye, or visual prosthesis, has gained a significant level of attention among researchers and ophthalmologists globally, because of its potential to assist those blinded or severely visually impaired by diseases such as retinitis pigmentosa (RP) and age–related macular degeneration (AMD).{{quote-A:R-W:450-Q: The device has some advantages over standard bionic eyes, insofar as it can potentially treat diseases at an earlier stage and stop vision loss, }}The simplistic overview of the technology, a digital camera fitted to a pair of glasses that transmits signals to a chip implanted in the eye, belies the complexity of interfacing man-made technology to the human user. Those signals, converted into electrical impulses, stimulate functional retinal cells directly. That output is interpreted as a crude ‘image’ by the patient’s visual cortex.Since a functional visual pathway is necessary for that technology to work, intraocular bionic eyes have been considered most suitable for conditions such as RP and AMD. The alternative approach of stimulating the visual cortex directly is also the subject of research. That approach is applicable to cases in which the lower parts of the visual pathway are incompetent.However, to date, unlike the intraocular implant approach, no commercial product has been released.Hoping to repeat the success of the Australian-developed cochlear implant, bionic eye research in Australia is being undertaken by two Melbourne-based projects – Bionic Vision Australia [intraocular] and the Monash Vision Group [cortical] – and a Canadian-Australian consortium, iBionics.Australia leadsCanadian-Australian start-up iBionics is attpting to improve the technology by using an innovative approach via its ‘Diamond Eye’. The company’s technology consists of a small chip (3.5 mm) using electrodes made of laboratory-manufactured, nitrogen-doped, diamond that is compatible with the human body. Developed in Australia by Bionic Vision Australia (BVA), this chip requires minimal power to stimulate the retina via its diamond electrodes.It is noteworthy that the performance of most devices is measured using the manufacturer’s own metrics, making it challenging to compare their efficacies; however, a consortium called Harmonization of Outcomes and Vision Endpoints in Vision Restoration Trials (HOVER) Taskforce is addressing this issue by developing standardised tests for devices.{{image2-a:l-w:400}}Australia is one of the leaders in the race to make the application of bionic eye routine. Bionic Vision Technologies (BVT), the follow up business of BVA, aims to commercialise advances developed by a leading national consortium of researchers, has been testing a prototype bionic eye device since 2012. It has recently started second phase trials with funding support from the National Health and Medical Research Council (NHMRC).It hopes the technology can be commercialised in the next 5–7 years, a prospect which was boosted in April thanks to an $18 million injection of funds from Hong Kong-based China Huarong International Holdings and State Path Capital.The next set of clinical trials will use next-generation, fully implantable, and portable prototypes consisting of an external vision-processing unit, camera, a pair of glasses, and an electrode array implanted beneath the retina.More recently, a team from two of BVT’s shareholders – the Bionics Institute and the Centre for Eye Research Australia (CERA) – won the top development project prize at the NHMRC’s Research Excellence Awards for a visual prosthesis based on a similar concept to the bionic eye, but a quarter of the size. The tiny implantable Minimally Invasive Retinal-degeneration Arrestor device sits unnoticed at the back of the eye and provides sporadic low-level electrical stimulation.This stimulation triggers the release of naturally occurring chicals that protect sight and prevent retinal cells from dying. The device has some advantages over standard bionic eyes, insofar as it can potentially treat diseases at an earlier stage and stop vision loss, instead of attpting to reverse it.Another major project is being undertaken by a consortium between Monash University, Alfred Health, MiniFAB and Monash Vision Group, which has invented a direct-to-brain bionic eye for patients suffering from blindness caused by other conditions such as trauma and glaucoma.The group expects that 85% of the clinically blind can benefit from the technology.There are numerous challenges that still need addressing. One of the major factors is cost – Argus II by Second Sight costs $US145,000 (AU$182,000) and as of 2016, only 80 people had used the technology. Such high costs may prove to be a major inhibitor in mass adoption of this device among the visually impaired especially when the modest improvent in ‘vision’ they offer is factored in.Bionic eyes cannot restore 6/6 vision and cannot restore vision for those who have never seen before. The best that these devices have been able to restore to date is 6/300, which is still well beyond even the legal definitions of blindness.The ‘vision’ provided by bionic eyes includes the ability to see contrasts and edges but only in black and white; however, future development announced by companies such as Second Sight hope to address these challenges and provide patients with the ability to see colour as well as images of higher resolution.Technical challengeA major technical challenge facing researchers is the complex structure of the retina and its numerous cells and cell types. Unlike the normal eye, the electrical stimulation of the retina by bionic-eye implants stimulate most or all cells simultaneously. The convergence of many retinal cells to far fewer optic nerve fibres is a further complication.{{image3-a:r-w:400}}The goal of future neural prosthesis development is to enable a one-to-one connection between the electrodes used in the bionic eye and neural cells, so that responses can be gathered from individual cells when such stimulation is delivered. By addressing this challenge, researchers aim to make vision enabled by implants as close as possible to natural vision.The future development of the bionic eye will occur through the evolution of technologies; however, to mimic the normal eye, revolutionary technologies and design approaches will need to address the mismatch between technology and biology at the neural interface.Futurists are predicting that this could make individuals superhuman with the ability to see through objects, detect micro-organisms without equipment, record what they see, sync the information with the internet, and possess infrared, night, and telescopic vision.There is already an iOS/Android app, developed by BVA, which allows individuals to experience simulated bionic eyes.It is expected that close co-operation between multidisciplinary researchers, such as professionals from the medical, biomedical, electrical engineering, and computer science fields, will evolve the efficacy of bionic eyes towards a brighter world for future generations.
| Transform livesThe market potential for bionic eyes is large – around 1.5 million people internationally suffer from blindness due to RP alone. while AMD is the single largest cause of irreversible blindness and visual impairment, especially among people over the age of 60.{{image4-a:l-w:400}}Macular Disease Foundation Australia states that one in seven Australians above the age of 50 are affected and 196 million people suffer from this disease globally, a number estimated to double by 2030.The World Health Organisation (WHO) estimates the total number of visually impaired people across the globe to be 285 million with 39 million completely blind. If successful and affordable, bionic eyes have the potential to truly transform the lives of millions of people worldwide.The US Food and Drug Administration first approved a bionic eye device, the Argus II (Second Sight Medical Products), in 2013. Surgeons at the University of Michigan Health Syst implanted it in 2014. Since then, numerous developments have taken place to make the project a commercial reality.Taking the visual cortex approach, a 30-year-old woman, who had started to lose vision eight years ago, was able to experience coloured flashes, lines, and spots via a visual stimulator chip implanted in her brain recently at University of California, Los Angeles. The team now plans to use tiny video glasses to generate signals sent directly the woman’s brain, bypassing the optic nerve altogether. Those video signals will be enabled by Second Sight’s Orion I, which has the ability to capture images in front of the eye using a spectacle-mounted camera.Another early entrant, Germany’s Alpha IMS from Retina Implant AG, has won CE mark certification and reimbursent approval in Germany. Unlike the Argus II, the company’s device does not have an external camera and is claimed to provide a better level of resolution (1,500 electrodes) and visual acuity.The French Pixium Vision device is similar to Argus II but claims advantages in resolution, speed, and efficiency. Pixium’s PRIMA syst, an advanced bionic-retinal syst being trialled for AMD, involves implantation of small photovoltaic diodes under the retina. This technology is expected to provide signalling similar to that anating from normal photoreceptors. |
