The Human Eye

The Eye

Most animals have light sensitive organs of some description these are generally classed as eyes. The eye takes many forms ranging from the simplest ones which are commonly found in invertebrates, which only consist of light sensitive cells on the surface of the body, to compound eyes which can see movement and finally to the most complex, the human eye, capable of forming complex images continuously.

The human eye consists of three main layers:
The scelera and cornea-the outer protective white coating of the eye
The uveal tract and choroid-the middle layer, which contains blood vessels that nourish the eye. It also contains the iris and the ciliray body.
And The Retina: the inner layer, which contains the nerves responsible for transmitting visual information to the brain for seeing.

The sclera and cornea give the eye protection and strength. The sclera covers five-sixths the eye and the cornea covers the rest. The scelera is the white part of the eye...