PRIMA System Helps 26 of 32 Patients Regain Central Vision
A revolutionary eye implant known as the PRIMA system has restored central vision to patients suffering from irreversible age-related macular degeneration (AMD), marking a historic advance in vision restoration. The clinical trial, conducted across 17 European hospitals, showed that 26 of 32 participants regained meaningful central sight within a year—many of whom could even read again.
“This is the first time any attempt at vision restoration has achieved such results in a large number of patients,” said Dr. José-Alain Sahel of the University of Pittsburgh School of Medicine, co-senior author of the study. “More than 80% of patients were able to read letters and words, and some of them are reading pages in a book. This is something we couldn’t have dreamt of when we started this journey 15 years ago.”
How the PRIMA Implant Works
Developed by ophthalmologist Daniel Palanker of Stanford University and led by Dr. Frank Holz of the University of Bonn, the PRIMA system consists of two components: a tiny wireless retinal implant and an external pair of smart glasses. The implant—a silicon chip just 2×2 millimeters wide and thinner than a human hair—contains 378 photovoltaic pixels. It is inserted behind the retina where vision loss is most severe.
The accompanying glasses capture images and convert them into near-infrared light at around 880 nanometers, invisible to the human eye. These signals are sent to the implant, which transforms them into electrical impulses that stimulate retinal cells and transmit visual data to the brain. Because the chip is powered by light, it operates wirelessly without an external power source.
“The system mimics how a natural eye processes light, bypassing damaged photoreceptors and directly activating the retina,” explained Palanker. “It’s effectively a photovoltaic prosthesis for the eye.”
Clinical Trial Results: Vision Restored for 81% of Patients
The trial enrolled 38 elderly patients across Europe, all diagnosed with advanced AMD and severe central vision loss. After excluding six participants lost to follow-up, 32 patients completed the 12-month study. Of them, 26—or 81%—experienced clinically meaningful vision improvement, with several reaching clarity near 20/420, the technical resolution limit of the device.
“Before receiving the implant, it was like having two black discs in my eyes,” recalled patient Sheila Irvine from the UK, who was treated at Moorfields Eye Hospital. “When I started recognizing letters again, I was overjoyed. Learning to read again isn’t easy, but every hour I practice, I see more.”
While 19 participants experienced side effects such as inflammation—common in eye surgery—most complications were mild and resolved quickly. Crucially, none lost peripheral vision. The device currently restores only black-and-white vision, but researchers are developing a grayscale version with higher resolution.
Next Steps: Toward Grayscale and Facial Recognition
“Number one on the patients’ wish list is reading, but number two, very close behind, is face recognition,” Palanker said. “To achieve that, we’re now working on grayscale imaging and finer pixel density for the next generation.”
The success of PRIMA represents a milestone in ophthalmology—an intersection of bioengineering, neuroscience, and precision medicine. If future versions continue to improve, the technology could restore meaningful sight to millions affected by macular degeneration worldwide.