Figure 1. Representative electroretinogram waveforms across flash stimuli recorded from implanted and contralateral eyes from each subretinal electrical stimulation (SES)–treated group and a naïve rat at 4 weeks post-op. Waveforms in the subretinal electrical stimulation (SES)–treated eyes were greater than in the opposite eyes in each group. Waveforms in the right and left eyes of the naïve rats were nearly identical. The large, fast, negative peak recorded from microphotodiode array (MPA)-implanted eyes is an “implant spike” caused by a rapid charge injection from the MPA in response to the brighter flash luminances.