- The term pseudentoptic phenomenon is indebted to the Greek words pseudos (untruthfulness), entos (inside), and opsis (seeing). It translates loosely as 'a visual phenomenon that is not truly derivative from inside the eye'. The term was introduced in or shortly before 1890 by the German ophthalmologist Ludwig Laqueur (18391909) to denote a visual percept that arises as a consequence of an object or stimulus that is projected on the outside of the corneal surface. An example of a pseudentoptic phenomenon is the *retinal shadow. The prefix pseudo refers to the fact that these phenomena are not attributable to a structure or process within the eye, as in *entoptic phenomena. Laqueur refers to a book published in 1767 by the French anatomist and surgeon Claude-Nicolas Le Cat (1700-1768) as the first reference to this phenomenon.ReferencesLaqueur, L. (1890). Ueber pseudentoptische Gesichtswahrnehmungen. Graefe's Archiv für Ophthalmologie, 36, 62-82. Le Cat, C.-N. (1767). Traité des sensations et des passions en général. Tome 1 et 2. Paris: Vallat-La-Chapelle.
Dictionary of Hallucinations. J.D. Blom. 2010.
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entoptic phenomenon — Also known as entoptic imagery, entoptic image, and entoptic form. All four terms are indebted to the Greek words entos (inside) and opsis (seeing). Traditionally the expression entoptic phenomenon is used to denote any member of a group of… … Dictionary of Hallucinations
retinal shadow — The term retinal shadow is indebted to the Latin noun retina (little net). It is used to denote a pseudentoptic phenomenon which is characterized by an inverted retinal image. A retinal shadow can be evoked experimentally by holding a pin… … Dictionary of Hallucinations