Anatomy of the Eye

Anatomy of the Eye

• The choroid layer forms the ciliary body and iris in the front of the eye.
• The iris is the pigmented and colored part of the eye, with a round opening in the center called the pupil.
• The pupil is controlled by the autonomic nervous system, with parasympathetic nerve fibers causing pupillary constriction and sympathetic fibers causing pupillary dilation.

Iris Muscles

• The iris contains circular muscle that constricts and radial muscle that dilates the pupil.
• The iris muscles act like a camera diaphragm, regulating the amount of light that enters the eye.

Ciliary Body

• The ciliary body is located behind the iris and produces aqueous fluid that fills the front part of the eye.
• The ciliary body has two major components: the ciliary muscle and the capillary network that produces the aqueous humor.

Crystalline Lens

• The crystalline lens is a transparent structure made up of transparent cells that lose their nucleus and organelles during development.
• The lens is attached to the ciliary muscle by suspensory ligaments (ciliary zonule).
• As a person grows older, the lens grows larger and thicker, becoming less elastic due to progressive denaturation of the lens proteins.

Lens Accommodation

• The ciliary muscle regulates the strength of the lens through accommodation.
• The strength of the lens depends on its shape, which is regulated by the ciliary muscle.
• When the ciliary muscle is relaxed, the suspensory ligaments pull the lens, making it slightly flat.
• When the ciliary muscle contracts, the lens becomes more spherical (convex), increasing its strength.