Purkinje images

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.

Purkinje-Sanson images are named after Czech anatomist Jan Evangelista Purkyně (1787-1869) and after French physician Louis Joseph Sanson (1790-1841).

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.

The first and fourth Purkinje images are used by some eye trackers, devices to measure the position of an eye.

ee also

*Red-eye effect

Brightness of Purkinje Images

The brightness of the Purkinje images can be determined using Fresnel's equation where theIntensity (Brightness)= (n'-n)^2/(n'+n)^2 Purkinje image I is the brightest of the four then PII, PIII and PIV (III and IV have about the same brightness).The Purkinje images can be used to assess the curvatures and separations of the surfaces in the eye.

External links

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


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Purkinje — is a name attributed to several biological features, so named for their discovery by Czech anatomist Jan Evangelista Purkyně: *Purkinje cells, located in the cerebellum *Purkinje fibers, located in the heart *The visual Purkinje effect *Purkinje… …   Wikipedia

  • Purkinje, Jan Evangelista — born Dec. 17, 1787, Libochovice, Bohemia died July 28, 1869, Prague, Czech. Czech experimental physiologist. He discovered the Purkinje effect (as light decreases, red objects appear to fade faster than blue ones), Purkinje cells (large branching …   Universalium

  • Purkinje-Sanson mirror images — Pur·kin·je San·son mirror images (pər kinґje sah sawґ) [J.E. Purkinje; Louis Joseph Sanson, French physician, 1790–1841] see under image …   Medical dictionary

  • Purkinje-Sanson mirror images — reflected images formed on the anterior surface of the cornea and the anterior and posterior surfaces of the crystalline lens. The images on the two anterior surfaces are virtual and noninverted, and the image on the posterior surface is real and …   Medical dictionary

  • Purkinje — Johannes E. von (Jan E. Purkyne), Bohemian anatomist and physiologist, 1787–1869. See P. conduction, P. images, under image, P. shift, subendocardial conducting system of heart, P. cells, under cell, P. corpuscles, under corpuscle, P. fibers,… …   Medical dictionary

  • Sanson images — Purkinje Sanson mirror i s …   Medical dictionary

  • Image Purkinje — Image Im age ([i^]m [asl]j; 48), n. [F., fr. L. imago, imaginis, from the root of imitari to imitate. See {Imitate}, and cf. {Imagine}.] 1. An imitation, representation, or similitude of any person, thing, or act, sculptured, drawn, painted, or… …   The Collaborative International Dictionary of English

  • imágenes de Purkinje-Sanson — Eng. Purkinje Sanson images Imágenes que se observan en la exploración de la pupila en el caso de transparencia del cristalino: la primera corresponde a la cara anterior de la córnea, la segunda a la cara anterior del cristalino y la 3ª invertida …   Diccionario de oftalmología

  • Sanson images — San·son images (sah sawґ) [Louis Joseph Sanson, French physician, 1790–1841] Purkinje Sanson mirror images; see under image …   Medical dictionary

  • image — 1. Representation of an object made by the rays of light emanating or reflected from it. 2. Representation produced by x rays, ultrasound, tomography, thermography, radioisotopes, etc. 3. To produce such representations. [L. imago, likeness]… …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”