One of them, called Argus II, was approved for commercial use in Europe in 2011 and in the United States in 2013. That implant involved larger electrodes that were placed on top of the retina. Its manufacturer, Second Sight, stopped producing the device in 2020 due to financial difficulties. Meanwhile, Neuralink and some others aim to bypass the eye entirely and instead stimulate the brain’s visual cortex.
Hodak says Prima differs from other retinal implants in its ability to provide “shape vision,” or the perception of shapes, patterns, and other visual elements of objects. However, what users see is not “normal” vision. For one thing, they don’t see in color. Rather, they see a processed image with a yellowish tint.
The trial enrolled people with geographic atrophy, an advanced form of age-related macular degeneration, or AMD, which causes gradual loss of central vision. People with this condition still have peripheral vision but have blind spots in their central vision, making it difficult to read, recognize faces, or see in low light.
In AMD, specialized cells called photoreceptors become damaged over time. Located at the back of the retina, photoreceptors convert light into signals that are sent to the brain. “The photoreceptors are lost but the retina is largely preserved. In our approach, the implant replaces the photoreceptors,” says Daniel Palanker, a professor of ophthalmology at Stanford University, who invented the Prima implant.