One of them, called Argus II, was approved for commercial employ in Europe in 2011 and in the US in 2013. This implant contained larger electrodes that were placed on the retina. Its manufacturer, Second Sight, stopped producing the device in 2020 due to financial difficulties. Meanwhile, Neuralink and several other companies intend 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. First, they cannot see color. Instead, they see a processed image with a yellowish tint.
The study included people suffering from geographic atrophy, an advanced form of age-related macular degeneration, or AMD, which causes a gradual loss of central vision. People with this condition still have peripheral vision, but have blind spots in their central vision, making it tough to read, recognize faces, or see in low featherlight.
In AMD, specialized cells called photoreceptors become damaged over time. Photoreceptors located at the back of the retina convert featherlight into signals sent to the brain. “The photoreceptors disappear, but the retina is largely preserved. In our approach, the implant replaces photoreceptors,” says Daniel Palanker, professor of ophthalmology at Stanford University, creator of the Prima implant.