A clinical trial of a new electronic eye implant has seen remarkable results. The study, published in the New England Journal of Medicine, showed 84% of participants were able to read letters, numbers and words using prosthetic vision through an eye that had previously lost its sight due to the untreatable progressive eye condition, geographic atrophy with dry age-related macular degeneration (AMD). They could also read, on average, five lines of a vision chart; some participants could not even see the chart before their surgery.
The trial, with 38 patients in 17 sites across five countries, involved the PRIMA device, Moorfields being the sole UK site. All patients had lost complete sight of their eye before receiving the implant.
Dry AMD is a slow deterioration of the cells of the macula over many years, as the light-sensitive retinal cells die off. For most people with dry AMD, they can experience a slight loss of central vision. Through a process known as geographic atrophy (GA), it can progress to full sight loss in the eye, as the cells die and the central macula melts away. There is currently no treatment for GA, which affects 5 million people globally. All participants in this trial had lost the central sight of the eye being tested, leaving only limited peripheral vision.
This revolutionary new implant is the first ever device to enable people to read letters, numbers and words through an eye that had lost its sight.
The procedure involves a vitrectomy, where the eye’s vitreous jelly is removed, and the surgeon inserts the ultra-thin microchip, which is shaped like a SIM card and just 2mm x 2mm. This is inserted under the centre of a patient’s retina, by creating a trapdoor into which the chip is posted. The patient uses augmented-reality glasses, containing a video camera that is connected to a small computer, with a zoom feature, attached to their waistband.
Around a month or so after the operation, once the eye has settled, the new chip is activated. The video camera in the glasses projects the visual scene as an infra-red beam directly across the chip to activate the device. Artificial intelligence (AI) algorithms through the pocket computer process this information, which is then converted into an electrical signal. This signal passes through the retinal and optical nerve cells into the brain, where it is interpreted as vision. The patient uses their glasses to focus and scan across the main object in the projected image from the video camera, using the zoom feature to enlarge the text. Each patient goes through an intensive rehabilitation programme over several months to learn to interpret these signals and start reading again.
No significant decline in existing peripheral vison was observed in trial participants. These findings pave the way for seeking approval to market this new device.
Sheila Irvine, one of Moorfields’ patients on the trial, said: “At first, I noticed I couldn’t judge things when I was driving - I kept hitting the pavement. I was told I had age-related macular degeneration. I cried all day long when I sent my driving licence back over 15 years ago, but then I said to myself, ‘Move on and get on with things.’
“I can't see TV very well, but I still have it on in the background. I don't let anything stop me. I’ve got lots of friends, and I socialise quite a bit, we catch up down the pub. And this country is wonderful - I get lots of assistance with transport, I still live by myself and want to stay independent.
“I wanted to take part in research to help future generations, and my optician suggested I get in touch with Moorfields. Before receiving the implant, it was like having two black discs in my eyes, with the outside distorted.
“I was an avid bookworm, and I wanted that back. I was nervous, excited, all those things. There was no pain during the operation, but you’re still aware of what’s happening. It’s a new way of looking through your eyes, and it was dead exciting when I began seeing a letter. It’s not simple, learning to read again, but the more hours I put in, the more I pick up.
“The team at Moorfields has given me challenges, like ‘Look at your prescription’, which is always tiny. I like stretching myself, trying to look at the little writing on tins, doing crosswords.
“It’s made a big difference. Reading takes you into another world, I’m definitely more optimistic now.”
Mahi Muqit, senior vitreoretinal consultant at Moorfields Eye Hospital and the Institute of Ophthalmology at UCL, added: “In the history of artificial vision, this represents a new era. Blind patients are actually able to have meaningful central vision restoration, which has never been done before. Getting back the ability to read is a major improvement in their quality of life, lifts their mood and helps to restore their confidence and independence. The PRIMA chip operation can safely be performed by any trained vitreoretinal surgeon in under two hours - that is key for allowing all blind patients to have access to this new medical therapy for GA in dry AMD.”
The research at Moorfields was delivered through the NIHR (National Institute for Health and Care Research) Clinical Research Facility (CRF) at Moorfields Eye Hospital NHS Foundation Trust.
The global trial was led by Dr Frank Holz of the University of Bonn, with participants from the UK, France, Italy and the Netherlands.
The PRIMA System device used in this operation is being developed by Science Corporation (science.xyz), which is a leader in brain-computer interfaces and neural engineering.
