Pupillary light reflex
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The pupillary light reflex or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity of light that falls on the retinal ganglion cells of the retina in
Variation in the size of the pupil in bright (left) and dim (right) environments. In this case the pupil is 3 mm in diameter on the left, and 9 mm on the right
Schematic diagram of pupillary light reflex neural pathway
A medical halogen penlight used to observe pupillary light reflex.
Eye
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An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons. It is part of an organism's visual system.
Pupillary light reflex
…the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness. A greater intensity of light causes the pupil to constrict…
Compound eye of an Antarctic krill
Eye of a European bison
Human eye
The eyes of a mantis shrimp (here Odontodactylus scyllarus) are considered the most complex in the animal kingdom.