The Prima system lets people with advanced age-related macular degeneration (AMD) read and do crosswords. Approved in Europe in July and awaiting FDA clearance in the US, it combines a retinal implant with camera-equipped eyeglasses to improve sight in patients who develop a blind spot in the middle of their vision due to advanced AMD. After training sessions, more than 80% of recipients were able to read, do crosswords, and use their phones.
The retina processes light in three layers: photoreceptors convert light into electricity, bipolar cells process that signal, and ganglion cells transmit the signal to the optic nerve and the brain. Prima replaces the photoreceptors. Developed by the California-based Science Corporation, the system leverages the fact that AMD doesn’t damage all retinal circuitry—only photoreceptors die off.
The implant mimics those cells 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," says Frank Brodie, an ophthalmologist at the University of California, San Francisco, and medical director for Prima. Glasses with a miniature front-facing camera capture what someone is seeing in real time. The video feed is roughly five megapixels at 30 frames per second, transmitted via fiber-optic cable to a handheld processor.
The processor converts the video into infrared light signals that route back to the glasses. A laser projector on the glasses shines near-infrared light pulses at 880 nanometers—an invisible wavelength—through the pupil to the retinal implant. The implant contains 378 pixels, each with an electrode and two photovoltaic cells that convert light into current for bipolar and ganglion cells and act as solar cells to power the chip, eliminating the need for a battery.
Source: MIT Technology Review · Summarized by HeadlinesBriefing