“…Several approaches have been proposed. For example, current steering, which involves passing current through several electrodes simultaneously in customized patterns, has been used in a range of neural structures from the cochlea (Townshend and White, 1987;Firszt et al, 2007) to deep brain nuclei (Martens et al, 2011) to the retina (Jepson et al, 2013;Matteucci et al, 2013;Dumm et al, 2014; see Bareket et al, 2017). Similarly, the use of local returns (rather than distant returns) to limit current spread without customization has been investigated using subretinal stimulation (Palanker et al, 2005;Palanker, 2014;Habib et al, 2013;Flores et al, 2016), suprachoroidal stimulation (Wong et al, 2009;Cicione et al, 2012;Sinclair et al, 2016), epiretinal stimulation , non-biological experiments (Dommel et al, 2005), and simulations (Joarder et al, 2011).…”