A retinal implant technology based on flexible polymer electrode and optical/electrical stimulation

Retinal implant is aimed at electronic stimulation of remaining retinal neurons in patients with degenerated photoreceptors. The Korean group for retina implants started development in year 2000, aiming for the rehabilitation of patients suffering from photoreceptor loss due to diseases such as aged-related macular degeneration (AMD) and retinitis pigmentosa (RP). To minimize the damage during ophthalmic surgery and to get better contact to the retina, flexible polyimide is selected as the substrate material of microelectrode arrays. Both the subretinal and epiretinal approaches are investigated in the group. For stimulation, we have considered both direct optical stimulation using unbiased photodiodes, and ordinary electrical stimulation based on cochlear implant-like electronics. The implanted retina produces EEPs (electrically evoked potentials) with typical peaks present, but with smaller latencies. In this presentation, we will describe the neuron-microelectronics interface, the stimulation methods, and the results of in-vitro and in-vivo animal tests.