Optimizing Stimulation Strategies for Retinal Electrical Stimulation: a Modelling Study.

In this research, a continuum multi-compartmental model of retinal electrical stimulation was utilized to find the best strategy for activating retinal ganglion cells (RGCs). Two types of return electrodes configuration placed suprachoroidally were used: monopolar and hexapolar. The current was delivered either simultaneously or sequentially with two kinds of waveforms: biphasic symmetric charge-balanced cathodic and anodic first pulses. Our results revealed there is no significant difference in current threshold between single monopolar and hexapolar stimulation regardless of the applied current stimulus waveform. Moreover, sequential stimulation for both monopolar or hexapolar was more effective in reducing current threshold than simultaneous stimulation when biphasic cathodic first pulses were used. Concurrent monopolar stimulation was significant in reducing the current threshold compared to single monopolar whereas concurrent hexapolar did not alter the current threshold. Overall, concurrent monopolar stimulation was efficacious in reducing current threshold regardless of the stimulus waveforms and sequential stimulation was more useful only with biphasic cathodic first pulses.