When Daniel Palanker first sketched out his idea for a wireless retinal implant in 2005, he imagined a chip small enough to slip under the retina that could convert light into electrical signals without any batteries, wires, or external power source. Twenty years later, that device has done something no eye prosthesis has managed before: it's restored the ability to read to people who had lost their central vision to macular degeneration.
The Reading Test That Changed Everything
The difference between previous vision implants and the PRIMA system comes down to what doctors call "form vision"—the ability to perceive shapes and patterns rather than just light and dark. In a clinical trial published in October 2025, 27 out of 32 patients who completed the one-year study regained the ability to read. Not just detect letters, but actually read books, food labels, and subway signs in their daily lives.
The average patient improved by five lines on an eye chart. One person improved by twelve lines. With digital enhancements like zoom and contrast adjustment, some participants achieved reading ability equivalent to 20/42 vision—good enough to pass a driver's test in some states.
These weren't young patients with decades of adaptation ahead of them. All 38 participants were over 60 with geographic atrophy from age-related macular degeneration, and all had vision worse than 20/320 when they started. Macular degeneration affects about 200 million people worldwide—in the U.S., it's as common as all invasive cancers combined.
A Chip Powered by Light
The PRIMA device works through elegant simplicity. A camera mounted on glasses captures what the wearer is looking at and projects that image using infrared light onto a chip implanted beneath the retina. The chip, measuring just 2-by-2 millimeters, contains 378 pixels that convert the infrared light directly into electrical current. That current stimulates the remaining retinal cells, which send signals through the optic nerve to the brain.
The photovoltaic design means no batteries to replace, no wires threading through the eye, no external power pack strapped to your body. The chip generates its own electricity from the light hitting it, the same way a solar panel does. It just sits there, waiting for light.
Patients retain their natural peripheral vision while the implant provides prosthetic central vision. This dual system helps with orientation and navigation—you can see movement and shapes around you naturally while reading or recognizing faces through the implant.
The Brain Learns to See Again
Visual acuity didn't peak immediately after surgery. It improved over months as patients trained with the device, similar to how cochlear implant recipients need time to make sense of prosthetic hearing. The brain has to learn a new language of vision.
The glasses allow patients to adjust contrast, brightness, and magnification up to twelve times, giving them control over their visual experience. Two-thirds reported medium to high satisfaction with the device. Nineteen participants experienced side effects including increased eye pressure, retinal tears, and bleeding under the retina, but none were life-threatening and almost all resolved within two months.
Currently, the device provides only black-and-white vision. Palanker is developing software to enable grayscale, which matters more than you might think. "Number one on the patients' wish list is reading," he says, "but number two, very close behind, is face recognition"—which requires the ability to distinguish shades.
Shrinking Pixels, Expanding Possibilities
The next generation chip tested in rats has pixels just 20 microns wide compared to the current 100 microns, packing 10,000 pixels onto the same size chip instead of 378. The math here is striking: a chip with 20-micron pixels could provide 20/80 vision naturally, and with electronic zoom, patients could achieve close to 20/20.
That would move vision implants from "functional" to "competitive with healthy eyesight." The difference between reading large print and reading anything you want.
When the Eye Itself Won't Work
PRIMA requires an intact retina and optic nerve to function—it's enhancing damaged biological systems, not replacing them. But what about people with total blindness, whose retinas or optic nerves are completely destroyed?
Philip Troyk at the Illinois Institute of Technology has spent nearly three decades developing an alternative: the Intracortical Visual Prosthesis, which bypasses the eye entirely and connects directly to the brain's visual cortex. In February 2022, surgeons at Rush University Medical Center implanted 25 wireless stimulators containing 400 electrodes into the first participant's visual cortex.
This approach works for anyone with an intact visual cortex, regardless of what happened to their eyes. The wireless stimulators are permanently implanted, eliminating the infection risk and maintenance burden of devices with external connections. After a recovery period of four to six weeks, testing began at The Chicago Lighthouse.
Reading in the Dark
Both approaches share a counterintuitive feature: they work in complete darkness. The PRIMA camera captures images regardless of ambient light, and the cortical implant doesn't need eyes at all. A person blind from birth could theoretically "see" through these systems, though the brain's ability to interpret visual information without prior experience remains an open question.
The devices also share a limitation: they're not restoring natural vision but creating a new kind of sensory experience that the brain interprets as vision. The resolution is lower, the field of view is narrower, and the image quality is crude compared to biological sight. But crude vision beats no vision when the alternative is permanent darkness.
Palanker's 2005 sketch has become a working prosthesis that lets people read again. The question now isn't whether neural implants can restore sight—it's how good that sight can become, and how many forms of blindness we can bypass entirely by going straight to the brain.