The eye can be thought of as three
spheres, one within the other. The protective outer
layer of the eye includes the Sclera and the clear
Cornea at the front of the eye. The middle layer
of the eye is the vascular layer which nourishes
the eye; it consists of the Choroid, the Ciliary
Body, and the Iris. The ciliary body has the dual
function of altering the focus of the lens and
making aqueous humor (see below). The innermost
layer of the eye consists of the Neural Retina
which covers the entire inside of the eye with
the exception of ciliary body and the iris. The
retina ends at the Ora Serrata. The Pupil is the
central opening in the iris and controls the amount
of light which enters the back of the eye. The
Anterior Chamber is the space between the cornea
and the iris and is filled with a clear fluid called
Aqueous Humor. The Lens is held in position behind
the iris by the Zonular Fibers. The lens focuses
light on the Neural Retina (or simply the Retina)
at the back wall of the eye. Nerve fibers from
the retina travel along the Optic Nerve to the
brain. The Vitreous Body (also called the Vitreous
Gel) is a clear gel which fills the relatively
large space between the lens and the retina.
The Macula is the central portion of the retina. The macula has specialized
cells (cones) which are responsible for color vision and for sharp, reading
vision.
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