Purkinje images are reflections of objects from the structure of the eye. They are also known as Purkinje reflexes and as Purkinje-Sanson images. At least four Purkinje images are usually visible. 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.
Read more about Purkinje Images: Brightness of Purkinje Images, See Also
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“What images are these
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