title: Position, size and luminosity of phosphenes generated by direct optic nerve stimulation.
abstract: Pulses of low intensity current, delivered through a cuff electrode chronically implanted around the optic nerve of a blind retinitis pigmentosa patient generate visual sensations. These phosphenes are obtained at lower thresholds for a train of stimuli than for single pulses, which suggests the existence of a spatial and temporal integrating mechanism. The perceptions are much smaller than those predicted from model simulations. A set of equations are derived which show the effect of pulse current, duration, number and frequency on the position, size and, to some extent, luminosity of the resulting phosphenes.
authors.affiliation: Neural Rehabilitation Engineering Laboratory, Université Catholique de Louvain, 54, Avenue Hippocrate, Box UCL 54.46, B-1200, Brussels, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Delbeke
authors.forename: Medhy
authors.initials: M
authors.lastname: Oozeer
authors.forename: Claude
authors.initials: C
authors.lastname: Veraart
mesh_terms: D000328:Adult; D001766:Blindness / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D009900:Optic Nerve / Q000503:physiopathology*; D010719:Phosphenes; D019919:Prosthesis Implantation; D011601:Psychophysics; D012174:Retinitis Pigmentosa / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D012684:Sensory Thresholds