Clinical trial of a next-generation electronic retina
On 8 June 2015, the first patient in the UK underwent surgical implantation of a next-generation Alpha AMS electronic retina manufactured by Retina Implant AG.
The new Alpha AMS subretinal implant represents a further refinement of the first generation Alpha IMS device which was implanted successfully in six patients in the previous pilot trial in 2012. The new subretinal implant has a greater number of pixels, a better power profile and other improvements to improve longevity.
Six more patients are participating in this new clinical trial of the next-generation electronic retinas. The implantation of the electronic retinas was undertaken at the John Radcliffe Hospital in Oxford by a surgical team led by Professor Robert MacLaren. Results thus far have been very encouraging - the previously blind patients are now able to detect light and recognise objects. One of the patients, Rhian Lewis, has been able to read the time on a clock after many years of blindness.
Original pilot trial in 2012
On 22 March 2012 Chris James became the first person in the UK to have an electronic retina implanted into the back of his eye, as part of a multicentre international clinical trial sponsored by Retina Implant AG, the manufacturer of the device.
The operation took place at the John Radcliffe Hospital in Oxford and the surgical team was led by Robert MacLaren, Professor of Ophthalmology at the University of Oxford.
The results of this study provided proof of principle that an electronic retinal implant can restore measurable visual function and potentially useful vision in blind or near-blind patients with end-stage degenerations of the outer retina such as retinitis pigmentosa.
How the electronic retinal implant functions
Electronic retinal implants are designed to replace the lost photoreceptors in the eyes of patients suffering from degenerative retinal diseases.
In many retinal diseases, such as retinitis pigmentosa, the photoreceptors die and therefore the light falling onto the retina can no longer be converted into electrical signals. The electronic retinal implant, which is a grid of photosensitive electrodes similar to those found in digital cameras, is able to act as an artificial layer of photoreceptor cells - that is to say, it is able to convert light into a pixelated array of electrical signals which can then be carried to the brain by the optic nerve.
The electronic retinal implant is inserted underneath the central part of retina (the macula), and is connected by an electrical cable to a subcutaneous power supply situated behind the ear.
The subcutaneous power supply can be recharged wirelessly via electromagnetic induction.