Accommodation reflex
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2008-05-30T14:13:57Z
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The '''accommodation reflex''' is a [[reflex action]] of the [[eye]], in response to [[focus (optics)|focusing]] on a near object, then looking at distant object (and [[vice versa]]), comprising coordinated changes in [[vergence]], [[lens (anatomy)|lens]] shape and [[pupil]] size. It is dependent on [[optic nerve|cranial nerve II]] ([[afferent limb]] of reflex), higher centres and [[oculomotor nerve|cranial nerve III]].
[[Image:Focus in an eye.svg|thumb|right|Light from a single point of a distant object and light from a single point of a near object being brought to a focus.]]
A near object (for example, a computer screen) appears large in the [[field of view|field of vision]], and the eye receives [[light]] from wide angles. When moving focus from a distant to a near object, the eyes converge. The [[ciliary muscle]] contracts making the [[lens (anatomy)|lens]] more convex, shortening its focal length. The [[pupil]] constricts in order to prevent diverging light rays from hitting the periphery of the [[retina]] and resulting in a blurred image.
==Pathway==
Light from each retina is taken to the [[occipital lobe]] via the [[optic nerve]] and [[optic radiation]], where it is interpreted as vision. The [[peristriate area 19]] interprets accommodation, and sends signals via the [[Edinger-Westphal nucleus]] and the [[Oculomotor nerve|3rd cranial nerve]] to the [[medial rectus]] muscle{{Fact|date=May 2008}}.
==See also==
*[[Accommodation (eye)]]
*[[Ciliary muscle]]
*[[Presbyopia]]
==External links==
*[http://hyperphysics.phy-astr.gsu.edu/hbase/vision/accom.html Accommodation] at [[Georgia State University]]
*{{MeshName|Ocular+Accommodation}}
{{Reflex}}
[[Category:Cranial nerves]]
[[Category:Eye]]
[[Category:Ophthalmology]]
[[Category:Reflexes]]
{{Neuroscience-stub}}
[[tr:Akomodasyon refleksi]]
[[uk:Акомодація ока]]