Editing Eye (section)

{{Short description|Organ that detects light and converts it into electro-chemical impulses in neurons}}
{{About|the organ present in many organisms|the human organ specifically|Human eye|the pupil|Pupil|the region of a cyclone|Eye (cyclone)|other uses|Eye (disambiguation)}}
{{Redirect-multi|3|Eyeball|Eyes|Ocular}}
{{pp-semi-indef|small=yes}}
{{EngvarB|date=October 2016}}
{{Infobox anatomy
| Name       = Eye
| Latin      = oculus
| System     = [[Nervous system|Nervous]]
| Image     = Krilleyekils.jpg
| Caption   = [[Compound eye]] of an [[Antarctic krill]]
| Image2      = Schematic diagram of the human eye en.svg
| Caption2    = Diagram of a [[human eye]]
}}

An '''eye''' is a [[sensory organ]] that allows an [[organism]] to perceive [[visual perception|visual]] information. It detects [[light]] and converts it into electro-chemical impulses in [[neurons]] (neurones). It is part of an organism's [[visual system]].

In higher organisms, the eye is a complex [[optics|optical]] system that collects light from the surrounding environment, regulates its intensity through a [[Iris (anatomy)|diaphragm]], [[Focus (optics)|focuses]] it through an adjustable assembly of [[Lens (anatomy)|lenses]] to form an [[image]], converts this image into a set of electrical signals, and transmits these signals to the [[brain]] through neural pathways that connect the eye via the [[optic nerve]] to the [[visual cortex]] and other areas of the brain.

Eyes with resolving power have come in ten fundamentally different forms, classified into [[compound eye]]s and non-compound eyes. Compound eyes are made up of multiple small visual units, and are common on [[insect]]s and [[crustacean]]s. Non-compound eyes have a single lens and focus light onto the retina to form a single image. This type of eye is common in mammals, including humans.

The simplest eyes are pit eyes. They are eye-spots which may be set into a pit to reduce the angle of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light.<ref name=Land1992>{{cite journal |first1=M.F. |last1=Land |first2=R.D. |last2=Fernald |year=1992 |doi=10.1146/annurev.ne.15.030192.000245 |title=The evolution of eyes |journal=[[Annual Review of Neuroscience]] |volume=15 |pages=1–29 |pmid=1575438|issn=0147-006X}}</ref>

Eyes enable several photo response functions that are independent of vision. In an organism that has more complex eyes, retinal [[photosensitive ganglion cell]]s send signals along the [[retinohypothalamic tract]] to the [[Suprachiasmatic nucleus|suprachiasmatic nuclei]] to effect circadian adjustment and to the [[pretectal area]] to control the [[pupillary light reflex]].