1,600 Photodiodes on a Tiny Retinal Chip

As part of the industry exhibition at the annual conference of the Retinologische Gesellschaft e. V. (German Retina Society) in Stuttgart on 23 and 24 June 2017, Retina Implant AG presented products and therapies to help people with retinitis pigmentosa. These included the RETINA IMPLANT Alpha AMS subretinal implant and the OkuStim System for Transcorneal Electrical Stimulation (TES). As part of the scientific programme, Prof. Florian Gekeler, Medical Director of the clinic of ophthalmology at the Katharinenhospital Stuttgart and scientist at Tübingen University, who has already implanted numerous retinal chips, gave a talk titled “Subretinal implant update – surgery and function”, in which he described his experiences.

Reutlingen-based Retina Implant AG develops and sells a retinal implant that can restore a certain degree of vision in patients who have gone blind as a result of retinitis pigmentosa. This has enabled patients to identify light sources such as windows and lamps in a room. This microchip is the result of 20 years of intensive research by Prof. Eberhart Zrenner from the Institute for Ophthalmic Research at Tübingen University and the Natural and Medical Sciences Institute (NMI), also at Tübingen University. The second generation of the chip, the CE-certified RETINA IMPLANT Alpha AMS, is now being presented in studies and presentations.

Retinal surgeon Prof. Florian Gekeler, Medical Director of the clinic of ophthalmology at the Katharinenhospital Stuttgart, is one of the few specialists who carries out the chip implantation. As he explained during his talk titled “Subretinal implant update – surgery and function” at the 30th annual conference of the German Retina Society in Stuttgart, “It is one of the most challenging surgical procedures out there.” To demonstrate the challenges involved, Gekeler compared the microchip to a pacemaker. “In heart surgery, two electrodes have to be protected in the body. The subretinal implant, on the other hand, contains 1,600.” The chip is just 12 square millimetres in size and is placed directly below the fovea centralis, the small pit at the back of the eye responsible for sharp vision. The chip is attached to the sclera, the white outer layer of the eyeball. The 1,600 photodiodes then partially replace the photoreceptors destroyed by the retinitis pigmentosa. Gekeler described impressive cases of patients who were able to distinguish shades of grey or even, in some cases, identify 10-centimetre letters after lives spent in total darkness.