Position, size and luminosity of phosphenes generated by direct optic nerve stimulation.
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.
Delbeke
Jean
J
Neural Rehabilitation Engineering Laboratory, Université Catholique de Louvain, 54, Avenue Hippocrate, Box UCL 54.46, B-1200, Brussels, Belgium.
Oozeer
Medhy
M
Veraart
Claude
C
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