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[[Image:Eyeball.jpg|right|thumb|Doctors performing an eye surgery.]]

In the human, and most mammals, the eye consists of several structures.  The cornea is a protective outer layer. The iris is an aperture through which light enters.  The lens is controlled by muscles to focus the light on the cornea - which is where the receptors for light are located.

 

The cornea has many specialized nerve endings that are able to react to light and send their signals via the optic nerve to the brain for interpretation.  There are receptors for subtle levels of light, which enable, at least, black and white vision in low-light environments.  There are also receptors that repsondf to higher levels of light that can perceive color.

The '''eye''' is the [[sensory organ]] that we see with. Typically they come in pairs, but [[spider]]s (for example) have eight eyes, and [[scallop]]s may have several dozen.

Typically eyes come in pairs, to allow binocular vision, which allows depth perception, but [[spider]]s (for example) have eight eyes, and [[scallop]]s may have several dozen.

== Diseases of the eye ==

== Diseases of the eye ==

The eye worm ''Loa loa'', a [[parasitism|parasitic]] [[nematode]] worm, inhabits the vitreous humour of the human eyeball in parts of Africa, and is often only detected when somebody sees the worm swimming across inside the eyeball. [http://www.paru.cas.cz/helminti/Nematoda/Loa_loa.gif]

The eye worm ''Loa loa'', a [[parasitism|parasitic]] [[nematode]] worm, inhabits the vitreous humour of the human eyeball in parts of Africa, and is often only detected when somebody sees the worm swimming across inside the eyeball. [http://www.paru.cas.cz/helminti/Nematoda/Loa_loa.gif]