Patients at several trial sites across Europe, including Moorfields eye hospital in London, were fitted with a surgically implanted microchip in their retina. Just 4mm square and 30 micrometres thick, the chip functions as a pattern converter. Visual information recorded by a camera in a pair of glasses is beamed to the chip via infrared light, which the chip converts to electrical signals detected by the retina, restoring the lost link between the eye and the brain. After one year, 84% of patients in the 38-person trial were able to read letters and numbers with the device, having previously lost vision, with the average improvement equal to about five lines on a standard eye-test chart.