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Encyclopedia > Purkinje images

Purkinje images are reflections of objects from structure of the eye. They are also know as Purkinje reflexes and as Purkinje-Sanson images. There are at least four Purkinje images that are visible on looking at an eye. The first Purkinje image (P1) is the reflection from the outer surface of the cornea. The second Purkinje image (P2) is the reflection from the inner surface of the cornea. The third Purkinje image (P3) is the reflection from the outer (anterior) surface of the lens. The fourth Purkinje image (P4) is the reflection from the inner (posterior) surface of the lens. Unlike the others, P4 is an inverted image. Look up reflection in Wiktionary, the free dictionary. ... This article or section does not cite its references or sources. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ... A lens is: a part of the eye an optical device that may be used in a camera or in a telescope; see lens (optics) or Category:Lenses. ...


Purkinje-Sanson images are named after Czech anatomist Jan Evangelista PurkynÄ› (1787-1869) and after French physician Louis Joseph Sanson (1790-1841). Greek anatome, from ana-temnein, to cut up), is the branch of biology that deals with the structure and organization of living things; thus there is animal anatomy (zootomy) and plant anatomy (phytonomy). ... Jan Evangelista PurkynÄ› (also written Johannes Evangelists Purkinje,  listen?) (1787 - 1869) was a Czech anatomist, patriot, and physiologist. ... Physician examining a child A physician is a person who practices medicine. ...


The third and fourth Purkinje images can be visible from within the eye itself. Light reflected away from the surfaces of the lens can in turn reflect back into the eye from the rear surface of the cornea. These images are, therefore, entoptic phenomena. Entoptic phenomena are visual effects whose source is within the eye itself. ...


The first and fourth Purkinje images are used by some eye trackers, devices to measure the position of an eye. An eye tracker is a device for measuring eye positions and eye movements. ...


See also

The red-eye effect in photography is the common appearance of red eyes on photographs taken with a photographic flash. ...

External links

  • Explanation of using purkinje images for eye tracking (http://www.diku.dk/~panic/eyegaze/node9.html).

  Results from FactBites:
 
Purkinje images - Wikipedia, the free encyclopedia (225 words)
The second Purkinje image (P2) is the reflection from the inner surface of the cornea.
The third Purkinje image (P3) is the reflection from the outer (anterior) surface of the lens.
The fourth Purkinje image (P4) is the reflection from the inner (posterior) surface of the lens.
  More results at FactBites »

 
 

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