Neuromodulation of the retina from the suprachoroidal space: The Phoenix 99 implant

Visual neuroprostheses aim to modulate the activity of surviving neurons of the visual system in an effort to elicit meaningful, psychophysical percepts. These percepts aim to aid a blind recipient in the conduct of day-to-day tasks such as navigation of unfamiliar environments, avoidance of obstacles, etc. The system architecture must balance myriad engineering, safety, and performance requirements including biocompatibility, charge neutrality, and the sustained provision of physiologically relevant stimuli to the visual system. At the same time, the system must become part of the target anatomy in order to interact and co-exist with surviving neuronal tissue. Here we describe a 99 channel visual neuroprosthesis with an array of 98 electrodes placed within the suprachoroidal space of the eye and a distant monopolar return electrode. Accordingly, we have created a system architecture and implemented a set of specifications that may serve to compensate for the loss of vision.