Retinal Implant Allows People with Blindness to Read Again in Small Trials

Scientists have used an eye implant to improve the vision of dozens of people rendered functionally blind by age-related macular degeneration (AMD). The implant, which measures 2 millimeters by 2 millimeters and is only 30 micrometers thick, is surgically inserted under the retina to replace light-sensitive cells lost to the disease.

The clinical trial, described today in The New England Journal of Medicineinvolved 38 people with advanced AMD whose retina had severely degenerated. One year after device implantation, 80% of participants saw a clinically significant improvement in their vision.

“Where this dead retina was a complete blind spot, vision was restored,” says Frank Holz, an ophthalmologist at the University of Bonn in Germany who led the trial. “Patients could read letters, they could read words, and they could function in their daily lives. »

On supporting science journalism

If you enjoy this article, please consider supporting our award-winning journalism by subscription. By purchasing a subscription, you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Despite some minor events related to the implantation surgery, the trial’s safety monitoring committee deemed the device’s benefits outweighed its risks. In June, the device’s owners – San Francisco-based neurotechnology company Science Corporation – applied for certification that would allow the device to be sold in the European market.

“I think this is an exciting and significant study, which was well designed and analyzed. It offers hope of providing insight to patients for whom it was more ‘science fiction’ than reality,” says Francesca Cordeiro, an ophthalmologist at Imperial College London.

Vision restored

AMD is the most common form of incurable blindness among older people. There are two main types, wet and dry AMD. The current work studied people with dry AMD, the advanced form of which affects around 5 million people worldwide. In dry AMD, light-sensitive cells in the central retina die over the years, leaving affected individuals with intact peripheral vision but without their high-acuity central vision. “They can’t recognize faces, they can’t read, they can’t drive a car, they can’t watch TV,” Holz says.

Dying photosensitive cells (rods and cones) convert light into electrochemical signals that are transmitted to other types of retinal neurons, which then send messages to visual processing regions of the brain. Because retinal neurons survive AMD, scientists reasoned that a light-sensitive implant that electrically stimulates the retina in the pattern of photons hitting it could restore the sense of vision.

The implant, called PRIMA – for photovoltaic retina implant microarray – was initially developed by Paris-based Pixium Vision and was acquired by Science Corporation last year. It is wireless, unlike previous retinal devices. And since it is a photovoltaic system, the photons that activate it also provide the energy source needed to produce electricity.

It is used in combination with glasses containing a camera that captures images and converts them into infrared light patterns that they transmit to the retinal implant.

The system, which allows users to zoom in and out of target objects and adjust contrast and brightness, requires, according to Holz, months of intensive training to use optimally.

In the current study, 38 people were treated at 17 clinical sites across 5 European countries, and 32 of the participants were tested one year after implantation. Twenty-six of them showed a clinically significant improvement in their vision – which, on average, was equivalent to being able to see two lines further on a standard letter board. Overall, the vision of most participants moved closer to the resolution achievable with PRIMA.

By the end of the study, most participants were using PRIMA at home to read letters, words, and numbers. Of the 32, 22 said their satisfaction was medium to high.

Slow reading

However, a questionnaire on users’ daily quality of life revealed no significant overall improvement. A retinal degeneration researcher working on treatments for vision loss, who wished to remain anonymous to avoid retaliation, spoke with Nature and raised concerns that intensive visual training and the motivation of having received an exciting medical device could have led to better test results. They said the results would have been more robust if gains had been demonstrated compared to a randomized placebo group that received the glasses and training protocols but not an implant.

Holz also acknowledges that the current system has limitations and says he expects future implants to be more effective. “This first major breakthrough constitutes a starting point for further improvements,” he says.

Another concern is the current maximum acuity that can be achieved with the current device. The PRIMA system has only 381 pixels, each measuring 100 square micrometers. And Holz concedes that users’ reading is “not fast, smooth reading.” The vision provided is also black and white and not color.

Holz says Daniel Palinker, a physicist at Stanford University in Palo Alto, Calif., who originally designed the device, has ideas about how to one day achieve color vision. A new generation device larger than PRIMA and filled with smaller pixels should enable better visual acuity. “It’s the beginning of a journey,” Holz says.

Although the device has been tested in people with AMD, it could also help restore sight in people affected by other conditions in which photoreceptor cells die but other retinal neurons remain functional, such as retinitis pigmentosa.

Retinal implants are not the only approach developed for this problem. Other researchers are exploring the use of stem cell therapies to regenerate photoreceptors; optogenetic therapies, in which photosensitive proteins are introduced into remaining retinal cells; and even implants inserted into the visual cortex of the brain.

“It’s a huge, dynamic space, and there are many approaches now,” Holz says. “What will end up happening, no one knows.”

This article is reproduced with permission and has been published for the first time October 20, 2025.