Phosphenes are percepts in one modality induced by an inappropriate stimulus, e.g., when pressure is applied to the eyeball, the mechanical stimulus may induce the perception of light. The perception of flashes of light when the eyes are moved has been reported in optic neuritis, presumably reflecting the increased mechanosensitivity of the demyelinated optic nerve fibers; this is suggested to be the visual equivalent of Lhermitte’s sign. Eye gouging to produce phosphenes by mechanical stimulation of the retina is reported in Leber’s congenital amaurosis.
Noise-induced visual phosphenes have also been reported, and may be equivalent to auditory-visual synesthesia.
Davis FA, Bergen D, Schauf C, McDonald I, Deutsch W. Movement phosphenes in optic neuritis: a new clinical sign. Neurology 1976; 26: 1100-1104
Lessell JB, Cohen MM. Phosphenes induced by sound. Neurology
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