Prima Retinal Implant Restores Vision for Advanced Macular Degeneration
Prima, a retinal implant with camera glasses, is approved in Europe and awaits FDA clearance for advanced AMD.
AMD affects more than 5 million people around the world, and until now no treatment could restore their vision. The condition damages photoreceptors, the cells that convert light into an electrical signal, while leaving other retinal circuitry intact. Prima replaces those photoreceptors. The retina processes light in three layers of cells: photoreceptors convert light into electricity, bipolar cells process that signal, and ganglion cells transmit the signal to the optic nerve and the brain.
Developed by California-based Science Corporation, Prima’s implant mimics photoreceptors and transmits visual information directly to healthy eye circuitry and on to the brain. “We’re leveraging all of the body’s own natural functions to process and transmit the information,” said Frank Brodie, an ophthalmologist at the University of California, San Francisco, and medical director for Prima.
The glasses are outfitted with a miniature front-facing camera that captures what someone is seeing in real time. The video feed is roughly five megapixels running at 30 frames per second, similar to TV. The raw video is transmitted to a connected processor via a fiber-optic cable. A small, handheld processor, which can be set on a table or tucked in a pocket, converts the video feed into infrared light signals that route back to the glasses. The device also includes physical buttons that let the wearer adjust contrast, brightness, and zoom.
A laser projector on the glasses faces the wearer and shines pulses of near-infrared light directly at the eye at 880 nanometers, an invisible wavelength. This signal passes through the pupil and on to the retinal implant in the back of the eye.
The implant is made up of 378 pixels, each with an electrode and two photovoltaic cells, which do double duty. They convert the light into a current that healthy bipolar and ganglion cells pass on to the brain. They also act as solar cells to power the chip, eliminating the need for a battery.