Anatomy and Functionality
The eyes are our sensory organs that we need to see all sorts of visible things.
When rays of light enter the eye, they are focused onto the retina by the cornea
and the lens. The nerve impulses produced by the retina are sent along the optic
nerve to the brain to produce the image that we see. The eye consists of many complicated
parts, including supportive layers, optical components and neural components.
The anatomy of the eye, taken from http://www.eyemdlink.com/pop/eyeAnatomy.htm
The eyeball is coated by sclera which is the white, dense, fibrous layer from condensation
of the mesenchyme. The cornea is a transparent layer of the eyeball which covers
the iris and pupil. The light rays pass to the lens through the pupil, which is
an opening in the centre of the iris. The iris is the colored diaphragm in the anterior
chamber of the eyeball which contracts and expands to control light intensity. The
lens is a dual-convex clear crystalline organ which focuses light rays onto the
retina. The vitreous fluid is a clear jellylike substance filling the posterior
chamber of the eyeball, normally attached to the retina. The retina is the membrane
on the inner wall of the eyeball divided into two developmental layers, the pigment
layer and the neural layer which receives the rays of light from the lens and converts
it into nerve impulses. These impulses travel along the optic nerve to the brain,
where they are converted to images.
There are two types of photoreceptors contained in the retina: rods and cones. With
their central location, cones are responsible for bright light and colors, while
the rods are responsible for peripheral and night vision. The macula refers to the
important centre of the retina, 5mm in diameter, which is responsible for central
vision. The fovea is the central area of macula which is responsible for sharp vision
and is the region of highest visual acuity and cone cell density.
The optic disc is the area where the optic nerve is connected to the retina and
can be seen as a bright yellow disc. All of the blood vessels supplying the retina
enter and exit via the optic disc. Its diameter is often used as a standard to measure
distances and sizes in the fundus image.