Simultaneous Perception of Phosphenes Generated by Direct Stimulation of a Human Optic Nerve

This study aims at understanding the effect of multiple stimulations of a human optic nerve. Phosphenes (visual sensations) were obtained by electrical stimulation of a four contacts spiral cuff electrode previously implanted around the right optic nerve of a completely blind retinitis pigmentosa patient. When a stimulation was made through several contacts or repeated, the patient perceived several phosphenes whereas when the stimulation was made through only one contact, the patient usually perceived only one phosphene. Moreover, when comparing different types of multiple stimulations (synchronous, interlaced and sequential), the most efficient was the synchronous stimulation.