Stanford Medicine researchers, together with international colleagues, have presented the results of a clinical trial that could transform the lives of millions suffering from severe vision loss. A miniature wireless chip implanted in the eye, used in combination with special glasses, enabled 27 out of 32 study participants to regain the ability to read.

The PRIMA eye prosthesis is an innovative system consisting of two main components. A tiny camera is mounted on the glasses, capturing images of the surrounding environment. The collected information is transmitted via infrared light to a chip just 2 by 2 millimeters in size, implanted in the retina. This device converts light signals into electrical impulses, effectively replacing lost photoreceptors.

The uniqueness of this development lies in the fact that the implant operates using the photovoltaic effect and does not require external power sources. This allows it to be safely placed beneath the retina. Patients can simultaneously use their remaining peripheral vision and the central vision restored by the prosthesis.

The study involved 38 people over the age of 60 with geographic atrophy—a severe form of age-related macular degeneration. This disease destroys central vision and is considered one of the leading causes of irreversible blindness in the elderly, affecting more than 5 million people worldwide.

The results exceeded expectations. Of the 32 participants who completed a year of follow-up, 27 were able to read, and 26 showed clinically significant improvements in visual acuity. On average, participants could see five lines better on the standard eye chart, and one patient improved by as many as 12 lines. Some achieved visual acuity of 20/42 thanks to the digital features of the glasses, such as adjustable magnification up to 12 times and enhanced contrast.

Participants began actively using the prosthesis in their daily lives. They read books, recognized product labels, and could read street signs. Two-thirds of the subjects reported moderate to high satisfaction with the device.

Although 19 participants experienced side effects, including increased intraocular pressure and peripheral retinal tears, all cases were non-serious and almost completely resolved within two months.

Currently, the PRIMA device provides only black-and-white vision, but developers are already working on software to transmit grayscale. The next generation of chips will feature pixels as small as 20 microns, compared to the current size, and up to 10,000 pixels per device.

Researchers plan for new versions, combined with electronic zoom, to allow patients to achieve visual acuity of 20/80, and eventually approach the normal level of 20/20. Work is also underway to create more compact glasses and adapt the technology to treat other types of blindness caused by photoreceptor loss.

The study results were published on October 20 in the prestigious New England Journal of Medicine. PRIMA has become the first eye prosthesis to restore functional vision to people with incurable vision loss, marking a new era in ophthalmology.