Dynamic current steering

Delivering weighted current to two or more neighboring electrodes at once to place a percept between the physical contacts, creating a virtual electrode and, in principle, more distinct phosphene locations than there are electrodes. Borrowed from cochlear-implant current steering, it trades electrode count for finer analog control of the stimulation field.

Its benefit is limited by current spread and by the physics of overlapping fields: steered phosphenes can merge or distort rather than cleanly interpolate, and gains in effective resolution are modest. Still, with sparse arrays it is one of the few knobs for pushing spatial resolution past the electrode pitch.