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 hallucinations of a * simple or * unformed nature. They are classified either as a type of *photopsia or as a type of *positive spontaneous visual phenomenon (PSVP). Phosphenes have been described in the medical literature since at least the fifth century BC. Ancient texts on phosphenes tend to focus on the alleged capacity of the eye to generate light for the purpose of vision. During the 19th century, the Bohemian physiologist Johannes Evangelista Purkyne (1787-1869) was among the first to make a significant contribution to the modern conception of phosphenes. Today the terms * deformation phosphene and * pressure phosphene are used interchangeably for a type of phosphene that can be provoked under physiological conditions through pressure onto the eyeball. Such types of phosphene may take the shape of a darkening of the visual field, of diffuse colour patches, of changing, scintillating, and deforming light-grids with occasional dark spots, and of fields with sparse, but intense blue points of light. Brief, recurrent, vertical phosphenes occurring in the temporal field of one eye are referred to as * Moore's lightning streaks. When phosphenes can be provoked by horizontal movement of the eyes, they are called * movement phosphenes. When they follow rapid eye movements (* REMs), especially in a dark environment, they are called * flick phosphenes. When they occur in reaction to a sudden sound, they are called * sound phosphenes. Phosphenes occurring in reaction to convergence of the eyes are designated as * convergence phosphenes. Phosphenes presenting as * formed hallucinations are sometimes referred to as * imagistic phosphenes. Pathophysiologically, phosphenes are associated with the random firing of neurons within any part of the *visual system, i.e. ranging from the retina to the lateral geniculate and stri-ate cortex. They can be provoked artificially by means of mechanical, electrical, and magnetic stimulation. Pathological causes of phosphenes include retinal detachment, optic neuropathy, and occipital haemorrhage. Movement phosphenes are associated primarily with optic neuritis. When phosphenes are attributed to intraocular mechanisms, they are classified as *entoptic phenomena.
   References
   Grüsser, O.-J., Hagner, M. (1990). On the history of deformation phosphenes and the idea of internal light generated in the eye for the purpose of vision. Documenta Ophthalmologica, 74, 57-85.
   Purkinje, J. (1819). Beiträge zur Kenntniss des Sehens in Subjectiver Hinsicht.Prague: Calve.
   Purkinje, J.E. (1819). Beobachtungen und Versuche zur Physiolgie der Sinne: Beiträge zur Kennt-niss des Sehens in subjectiver Hinsicht. Prague: Calve.

Dictionary of Hallucinations. . 2010.

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  • Phosphene — is also a common alternative spelling of Phosphine, PH3, a toxic and explosive gas. rightA phosphene is an entoptic phenomenon characterized by the experience of seeing light without light actually entering the eye. The word phosphene comes from… …   Wikipedia

  • phosphène — [ fɔsfɛn ] n. m. • 1838; du gr. phôs « lumière » et phainein « briller » ♦ Méd. Sensation lumineuse qui résulte de l excitation des récepteurs rétiniens par un agent autre que la lumière (choc, compression externe ou interne du globe oculaire,… …   Encyclopédie Universelle

  • Phosphene — Phosphène Un phosphène est un phénomène interne à l œil qui se traduit par la sensation de voir une lumière ou par l apparition de taches dans le champ visuel. Les phosphènes peuvent être causés par une stimulation mécanique, électrique, ou… …   Wikipédia en Français

  • Phosphene — Phos phene, n. [Gr. ? light + ? to show.] (Physiol.) A luminous impression produced through excitation of the retina by some cause other than the impingement upon it of rays of light, as by pressure upon the eyeball when the lids are closed. Cf.… …   The Collaborative International Dictionary of English

  • phosphene — [fäs′fēn΄] n. [< Gr phōs, light (see PHOSPHORUS) + phainein, to show (see FANTASY)] a sensation of light produced by mechanical or electrical stimulation of the retina, as by pressure on the eyeball through the closed eyelid …   English World dictionary

  • Phosphène — Un phosphène est un phénomène qui se traduit par la sensation de voir une lumière ou par l apparition de taches dans le champ visuel. Les phosphènes peuvent être causés par une stimulation mécanique, électrique, ou magnétique de la rétine ou du… …   Wikipédia en Français

  • phosphene — /fos feen/, n. Physiol. a luminous image produced by mechanical stimulation of the retina, as by pressure applied to the eyeball by the finger when the lid is closed. [1870 75; < F phosphène, irreg. < Gk phôs light (contr. of pháos) + phaínein to …   Universalium

  • phosphene — phos•phene [[t]ˈfɒs fin[/t]] n. oph a luminous visual image produced by mechanical stimulation of the retina, as when pressing on closed eyelids • Etymology: 1870–75; < F phosphène, irreg. < Gk phôs light (contr. of pháos) +phaínein to show …   From formal English to slang

  • phosphene — noun Etymology: International Scientific Vocabulary phos + Greek phainein to show more at fancy Date: circa 1860 a luminous impression due to excitation of the retina …   New Collegiate Dictionary

  • Phosphene — Phosphäne (v. griech. φῶς „Licht“ und φαίνειν „erscheinen“) sind Lichtwahrnehmungen, die nicht durch Licht, sondern durch andere Stimuli erzeugt werden. Dies können Wahrnehmungen durch Halluzinationen, physikalischen Druck auf die Netzhaut,… …   Deutsch Wikipedia

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