Vision Loss Breakthrough: Eye Implant Helps Patients With Advanced AMD Finally Read Again

A wireless microchip implanted beneath the retina improved vision in 81% of patients with advanced age-related macular degeneration, allowing some to read again after years of severe vision loss. The device works with camera-equipped glasses that capture images and project them onto the chip using infrared light, which the implant converts into electrical signals the brain can interpret.

In a clinical trial involving 38 patients across Europe, most of those assessed at 12 months showed substantial improvement in their ability to see. Some went from profound vision loss to reading small print, marking what researchers describe as the first intervention to improve lost vision in this patient population rather than simply slow disease progression.

Age-related macular degeneration affects more than 5 million people worldwide and accounts for roughly 20% of all legal blindness cases in North America. Geographic atrophy, the advanced form of dry AMD studied in this trial, causes cells in the center of the retina to progressively die. As of this study period, no treatment existed to bring back vision once those cells were gone.

The PRIMA Eye Implant

The photovoltaic retina implant microarray, or PRIMA system, replaces the function of dead light-sensing cells with technology. Surgeons place a 2-millimeter square chip that’s thinner than a human hair beneath the retina in the area of vision loss.

Patients wear specialized glasses with a built-in camera that captures whatever they’re looking at. That visual information gets processed through a pocket-sized device, then projected back through the glasses onto the implant using infrared light (a type of light the eye can’t see naturally). The chip’s 378 tiny pixels convert this light into electrical pulses that stimulate the remaining healthy retinal cells, essentially restarting the flow of visual information to the brain.

Unlike other assistive devices that magnify images for healthy parts of the retina, PRIMA targets the blind spot directly while leaving natural side vision untouched. The transparent lenses mean users experience both artificial central vision and their remaining natural sight at the same time.

“All previous attempts to provide vision with prosthetic devices resulted in basically light sensitivity, not really form vision,” said Daniel Palanker, a Stanford professor of ophthalmology and a co-senior author of the New England Journal of Medicine paper, in a statement. “We are the first to provide form vision.”

Patients Gained Reading Ability After Years of Vision Loss

Among the 32 participants evaluated at one year, 26 showed improvement equivalent to gaining 10 or more letters on a standard eye chart. The average improvement was about 25 letters, while one patient improved by roughly 59 letters.

Participants could adjust zoom and brightness on their glasses during vision tests. Features like contrast adjustment and magnification helped users see more than the chip’s basic resolution would normally allow.

At home, 84% of participants reported using the device to read letters, numbers, and words. About 69% said they were moderately to highly satisfied with the system. Three participants from an earlier study maintained vision sharp enough to read small fonts four years after getting the implant.

However, there’s an important caveat. Despite better scores on eye charts and self-reported reading improvements at home, a standardized questionnaire measuring quality of life showed no change from before the surgery at 6 or 12 months. Researchers say the questionnaire may not be sensitive enough to detect changes in people with extremely poor baseline vision.

Study participants had been living with profound vision loss. The average age was 79 years, and all had geographic atrophy affecting their central vision. Most had lost the ability to read, recognize faces, or perform other tasks requiring sharp central vision.

“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,” said Sheila Irvina, one of the patients in the study who underwent surgery at Moorfields Eye Hospital in London. “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.”

Surgery Carries Risks Common to Eye Procedures

Twenty-six serious complications occurred in 19 participants within 12 months of surgery, though researchers emphasize all were anticipated. Most complications happened within two months of the procedure, and 95% of early complications resolved within two months.

Elevated eye pressure affected six patients, appearing between day one and week three after surgery. All cases went away on their own. Five participants experienced small retinal tears during surgery, all repaired immediately without causing retinal detachment.

Three patients developed full-thickness holes in the macula (the central part of the retina). Two needed their implants repositioned away from the hole. One participant experienced multiple serious complications including retinal detachment, but was successfully treated with additional surgery.

Side vision after getting the implant remained just as good as before surgery, indicating the procedure didn’t damage the healthy retina surrounding the treated area.

Why This Approach Works Better Than Previous Eye Implants

Earlier attempts at artificial vision using different implant types didn’t work as well. An earlier device, Argus II, had a larger spacing between electrodes and stimulated cells farther from where they naturally receive signals, resulting in distorted vision and reduced sharpness.

PRIMA’s placement beneath the retina (rather than on top of it) and its wireless design were engineered to make surgery simpler than with earlier systems. The chip sits closer to the cells it needs to stimulate, which improves how well patients can see. Stimulating cells earlier in the vision pathway preserves more of the eye’s natural signal processing. Even small eye movements can help improve clarity beyond what the pixel size would suggest.

The wireless nature means no permanent openings in the eyeball, unlike older wired implants. The chip is extremely thin, about half the height of a natural light-sensing cell, which allows it to integrate with surrounding tissue without needing screws or tacks to hold it in place.

Current Limitations and Ongoing Research

Six participants weren’t evaluated at 12 months: three had died from causes unrelated to the study, one dropped out, and two weren’t available for testing.

The treated eyes showed greater disease progression than the untreated eyes. Researchers attribute this to the surgery itself rather than the device, since the progression occurred in areas where surgical instruments created temporary fluid pockets and small openings. Treated eyes showed an average disease progression of 8.5 square millimeters over the year, compared to 2.5 square millimeters in untreated eyes.

PRIMA’s wireless design could theoretically allow doctors to replace it with higher-resolution versions in the future, or even place multiple chips across a larger blind spot with minimal incisions. Participants using zoom and other digital features could read fonts smaller than the hardware alone should allow, suggesting the combination of chip and image processing extends useful vision.

Researchers plan to follow participants for up to three years after surgery. The first therapies recently approved for geographic atrophy work by slowing disease progression through monthly or twice-monthly injections. PRIMA takes a fundamentally different approach: rather than trying to keep cells alive, it replaces their function once they’re already dead.

For patients with geographic atrophy, these results offer something no previous treatment could. While drugs like pegcetacoplan and avacincaptad pegol can slow the spread of damage, they can’t reverse vision that’s already gone. PRIMA fills that gap by creating an artificial way to transmit visual information from areas where light-sensing cells have died.

“This is the first version of the chip, and resolution is relatively low,” said Palanker. “The next generation of the chip, with smaller pixels, will have better resolution and be paired with sleeker-looking glasses.”

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