04 May 2012
Electronic retinal implants restore ‘useful vision’ to blind patients
The first blind patients to be fitted with electronic eye implants in a UK clinical trial have regained 'useful vision' only weeks after surgery.
Chris James and Robin Millar, who have an inherited form of blindness called retinitis pigmentosa, were said to be able to perceive light and even some shapes just three weeks after the innovative retinal devices were fitted.
The technology relies on a wafer thin 3mm2 microchip consisting of 1,500 tiny electronic light detectors implanted below the retina. The implant works by sending electronic signals from the chip to the optic nerves, which are stimulated by small electrodes to create a pixellated image.
"'What makes this unique is that all functions of the retina are integrated into the chip," explained lead surgeon Robert MacLaren, a professor of Ophthalmology at the University of Oxford. "It has 1,500 light sensing diodes and small electrodes that stimulate the overlying nerves to create a pixellated image. Apart from a hearing aid like device behind the ear, you would not know a patient had one implanted."
The operation first required implantation of a power supply which was buried under the skin behind the ear in a similar fashion to a cochlear implant. The electronic retina was then inserted into the back of the eye and stitched into position before being connected to the power supply.
Three weeks after the operation, patient Chris James' electronic retina was switched on for the first time. After some initial tuning and testing, he was able to distinguish light against a black background. "As soon as I had this flash in my eye, this confirmed that my optic nerves are functioning properly which is a really promising sign,' he said. 'It was like someone taking a photo with a flashbulb, a pulsating light, I recognised it instantly.'
Prof MacLaren noted: "We are all delighted with these initial results. The vision is different to normal and it requires a different type of brain processing. We hope, however, that the electronic chips will provide independence for many people who are blind from retinitis pigmentosa."