A tiny electronic implant paired with special glasses has helped restore functional vision in patients with advanced dry age-related macular degeneration (AMD), an incurable cause of blindness, medical researchers announced on Monday.
Twenty-seven (84 per cent) of 32 patients with AMD who participated in a clinical trial across five countries were able to read letters, numbers and words using the implant, the researchers said, reporting their findings in the New England Journal of Medicine.
With the device, the patients were able to read on an average five lines on a vision chart. Some patients had been unable to even see the charts before they received the implants.
All previous attempts to provide vision with prosthetic devices had resulted in light perception, not form vision, which is the ability to perceive shapes and patterns, said Daniel Palanker, professor of ophthalmology at Stanford University who co-led the research.
“We are the first to provide form vision,” Palanker said in a media release from Stanford.
Advanced AMD destroys light-sensitive cells in the macula, the retina’s central part responsible for sharp vision, leading to a blurry or blank spot at the centre of sight. The disease, which often leaves peripheral vision intact, affects over five million people worldwide.
(Left) Simulation of a patient's vision with macular degeneration. (Right) Simulation of a patient's vision enhanced with the implant. Credit: Palanker Lab / Stanford Medicine
The implant, designed by Palanker and collaborator José-Alain Sahel at the University of Pittsburgh, bypasses the dead light-sensitive cells by converting light captured in the residual retina into electrical signals that are transmitted to the brain.
During the procedure, surgeons remove the vitreous jelly between the lens and the retina and implant a 2mm×2mm microchip, about half the thickness of a human hair, under the centre of the retina.
A month later the chip is activated, sending signals the brain interprets as vision, and patients undergo training to learn to focus, zoom and read again.
In the trial, 19 patientsexperienced temporaryside effects, including ocular hypertension and sub-retinal bleeding, but they wereall resolved within two months with no life-threatening events.
With digital enhancements such as zoom and higher contrast, some participants could read with acuity equivalent to 20/42 vision — on a standard eye chart, they could see letters at 20 feet that most people with normal eyesight could see from 42 feet.
Based on the trial results, Science Corporation, a US company developing advanced medical technologies, has applied for clinical-use authorisation in Europe and the US.
“While we can’t restore full 20/20 vision with the implant alone, we are now investigating methods that could further improve people’s quality of life,” Sahel said.
The implant has emerged after nearly two decadesof development, including prototypes, animal trialsand a first-in-human trial in 2020.
Palanker first envisioned the device in 2005 while working with ophthalmic lasers to treat eye conditions.
Currently, the device provides only black-and-white vision. Palanker and his colleagues are working on software to enable the full range of grayscale, important for face recognition.
Scientists hope to engineer future chips for higher resolution, aimed at further improvements in vision.
The global trial, led by Frank Holz of the University of Bonn, included participants from the UK, France, Italy and the Netherlands.
Mahi Muqit, an associate professor at the University College London (UCL)Institute of Ophthalmology, said: “Blind patients are actually able to have meaningful central vision restoration (with the implant), whichhas never been donebefore.”
“Before receiving the implant, it was like having two black discs in my eyes,” Sheila Irvine, one of the trial participants in the UK, said in a UCL media release.
“I was an avid bookworm, and I wanted that back…. There was no pain duringthe operation, but you’re aware of what’s happening,” she added.
“It’s a new way of looking through your eyes, and it was exciting when I began seeing a letter. It’s not simple, learning to read again, but the more hours I put in, the more Ipick up.”