A wireless eye implant has restored reading ability to people with advanced macular degeneration. The photovoltaic retina implant microarray (PRIMA) chip, as the BBC reports, works with smart glasses to replace lost photoreceptors using infrared light. This is the first prosthetic eye device to restore usable vision to individuals with otherwise untreatable vision loss.
From the study conducted, most trial participants (27 out of 32 people) regained functional vision, reading books and recognising signs. In addition, with the help of digital features such as adjustable zoom and enhanced contrast, some participants achieved visual sharpness comparable to 20/42 vision.
Each participant in the trial had an advanced stage of age-related macular degeneration known as geographic atrophy, which progressively destroys central vision.
In macular degeneration, the light-sensitive photoreceptor cells in the central retina deteriorate, leaving only limited peripheral vision. However, many of the retinal neurons that process visual information remain intact, and PRIMA capitalizes on these surviving structures.
The researchers, from Stanford Medicine, are now developing higher-resolution versions that could eventually provide near-normal sight.
The system includes two main parts: a small camera attached to a pair of glasses and a wireless chip implanted in the retina. The camera captures visual information and projects it through infrared light to the implant, which converts it into electrical signals. These signals substitute for the damaged photoreceptors that normally detect light and send visual data to the brain.
The implant, measuring just 2 by 2 millimetres, is placed in the area of the retina where photoreceptors have been lost. Unlike natural photoreceptors that respond to visible light, the chip detects infrared light emitted from the glasses.
Since the implant is photovoltaic -- relying solely on light to generate electrical current -- it operates wirelessly and can be safely placed beneath the retina. Earlier versions of artificial eye devices required external power sources and cables that extended outside the eye.
The PRIMA project represents decades of scientific effort, involving numerous prototypes, animal testing, and an initial human trial.
The participants, across the course of one year, used the prosthesis in their daily lives to read books, food labels and subway signs. The glasses allowed them to adjust contrast and brightness and magnify up to 12 times. Two-thirds reported medium to high user satisfaction with the device.
According to lead researcher, Daniel Palanker: "All previous attempts to provide vision with prosthetic devices resulted in basically light sensitivity, not really form vision...We are the first to provide form vision."
The PRIMA device provides only black-and-white vision, with no shades in between, however Palanker is developing software that will soon enable the full range of grayscale. He is also engineering chips that will offer higher resolution vision.
The research paper appears in the New England Journal of Medicine, titled "Subretinal Photovoltaic Implant to Restore Vision in Geographic Atrophy Due to AMD."