Pioneering PRIMA eye device restores reading vision to blind eyes - NIHR Biomedical Research Centre: Moorfields

An older person wearing a black hat and special glasses sits at a desk using assistive technology to read enlarged text on a computer screen. The screen displays large black text on a yellow background that reads, “I went to the hospital to get my eye checked up.” Another person sits beside them, observing.

A pivotal European clinical trial of a new electronic eye implant has seen remarkable results that will have lasting impact on patients with sight loss.

The PRIMA trial, 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 eye condition, geographic atrophy with dry age-related macular degeneration (AMD). All the participants in this trial had lost the central sight of the eye being tested, leaving only limited peripheral vision. After the trial they could read, on average, five lines of a vision chart; some participants could not even see the chart before their surgery.

The truly international trial, worked with 38 patients in 17 sites across five countries, with Moorfields Eye Hospital being the sole UK site taking place in the NIHR Moorfields Clinical Research Facility.

How does it work?

The procedure involves a surgeon inserting an ultra-thin, half the width of a human hair, 2mm wide microchip, under the centre of a patient’s retina, by creating a trapdoor into which the chip is posted. Around a month or so after the operation, the microchip is activated. The patient then uses augmented-reality glasses, containing a video camera that is connected to a small computer, with a zoom feature, attached to their waistband.

Image shows microchip implant on the end of a finger to give an idea of scale — The implant shown on the end of a finger for scale

Image shows a plain fundus photograph, pink with vascular systems showing, next to one of an implant in the eye. below is an oct scan showing the implant in place — The implant shown in the eye via Fundus and OCT imaging

A video camera in the glasses projects the visual scene directly across the chip which activates the device. Artificial intelligence (AI) algorithms in the pocket computer process this information, which is 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.

Professionally dressed man wearing a dark suit, light blue shirt, and blue striped tie, with rectangular eyeglasses and short dark hair graying at the temples, posed against a plain white background

Mahi Muqit, Senior vitreoretinal consultant at Moorfields Eye Hospital and NIHR Research Investigator,

“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.”

Each patient goes through an intensive rehabilitation programme over several months to learn to interpret these signals and start reading again.

Image shows a white woman in a headwrap and a white cardigan, she is Sheila Irvine

Sheila Irvine Moorfields’ patients on the trial

“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 simple, learning to read again, but the more hours I put in, the more I pick up.”

The global trial was led by Dr Frank Holz of the University of Bonn, with participants from the UK, France, Italy and the Netherlands. We look forward to hearing more results.

Further Reading