- convergence phosphene
- A term used to denote a *phosphene (i.e. 'seeing stars') arising physiologically in association with convergence of the eyes. In 1978 the American neuroscientist Christopher W. Tyler proposed a distinction between two types of convergence phosphene: one mediated by rapid convergence movements, and one mediated by prolonged convergence movements. Phenomenologi-cally, the type of phosphene which follows rapid convergence movements is characterized by two large rings that can be seen best in a dark environment. This type is also referred to as the fiery rings of Purkinje, after the Bohemian physiologist Johannes Evangelista Purkyne (1787-1869), who described the phenomenon in his textbook of 1823. The mediation of the fiery rings of Purkinje is attributed to stretching of the optic nerves and the region of the papillae, followed by peripheral neuronal discharges. The second type of convergence phosphene, occurring after sustained convergence of the eyes, can be best perceived with eyes closed against an illuminated background. This type is characterized by a red dumbbell-shaped form that extends horizontally from the region of the fovea to the periphery. Because of its shape, this type of phosphene is also referred to as a dumbbell phosphene or dumbbell-shaped phosphene. Convergence phosphenes are classified either as *entoptic phenomena or as * physiological illusions. The term convergence phosphene is used in opposition to the terms *flick phosphene, *movement phosphene, and *sound phosphene.ReferencesPurkyne, J.E. (1823). Beobachtungen und Versuche zur Physiologie der Sinne I. Prague: Calve.Tyler, C.W. (1978). Some new entoptic phenomena. Vision Research, 18, 1633-1639.
Dictionary of Hallucinations. J.D. Blom. 2010.
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phosphene — Also known as unstructured photopsia. The term phosphene comes from the Greek words phos (light) and phainein (to shine). It is used to denote a transient flash or spark of light, commonly referred to as seeing stars . Phosphenes are * visual… … Dictionary of Hallucinations
dumbbell phosphene — Also known as dumbbell shaped phosphene. Both terms are used to denote a type of phosphene (i.e. seeing stars ) that may arise after sustained convergence of the eyes, especially with closed eyes against an illuminated background. The name… … Dictionary of Hallucinations
flick phosphene — Also known as eye movement phosphene. The term flick phosphene was introduced in or shortly before 1957 by the American ophthalmologist Bernard R. Nebel, who had observed the concomitant phenomenon in himself. The term is used to denote a type … Dictionary of Hallucinations
movement phosphene — A term introduced in or shortly before 1976 by the American neurologists Floyd A. Davis et al. to denote a type of * phosphene (i.e. a transient flash or spark of light) that may be evoked by eye movement. Etiologically, movement phosphenes… … Dictionary of Hallucinations
sound phosphene — A term used to denote a type of synaesthesia characterized by a transient flash or spark of light (i.e. a *phosphene) which is triggered by a sudden sound. Sound phosphenes are typically perceived in a dark environment. A special variant is… … Dictionary of Hallucinations
fiery rings of Purkinje — The eponym fiery rings of Purkinje refers to the Bohemian physiologist Johannes Evangelista Purkyne (1787 1869), who is credited with being the first to describe the concomitant phenomenon in his textbook of 1823. The phenomenon consists of… … Dictionary of Hallucinations
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