Prototype Hardware for Closed-loop Stimulation of the Retina.

Since the first human trial demonstrated the potential of retinal prostheses in 1956, research on retinal stimulation for vision restoration has been intensive. Compared to the advancements in stimulating electrodes and electronics, relatively less progress has been made in stimulation strategies. Current devices largely rely on manually tuned stimulation generated solely from camera inputs. As electrode pitch continues shrinking to improve visual acuity, manually tuning stimulation parameters becomes increasingly impractical. Moreover, the manual approach fails to account for time-dependent physiological variations. This limitation compromises visual acuity and highlights the need for more adaptive solutions.A closed-loop stimulation strategy that evaluates neural responses and adaptively optimizes stimulation in real-time could address these limitations. Developing such a strategy requires a hardware platform capable of chronic operation, simultaneous multi-electrode stimulation, and neural recording.In this work, we present an implantable hardware platform based on commercially available neural stimulating application-specific integrated circuits (ASICs), designed to electrically evoke and capture neural responses of the retina. We evaluated a benchtop prototype in an in vivo pilot study (N=1), confirming its functionality and neural recording capability.Clinical relevance: This platform lays the groundwork for training and evaluating closed-loop strategies, paving the way for more advanced and adaptive retinal prostheses that can deliver improved bionic vision, thereby enhancing outcomes for end-users.