Eye Structures

Optic Nerve

Axons of retinal neurons that leave the eye.

Iris

Colored, muscular portion of the eye that surrounds the pupil and regulates its size. Contains smooth and connective tissues and divides the anterior cavity.

Anterior Chamber

Division of the anterior cavity between the cornea and the iris.

Posterior Chamber

Division of the anterior cavity between the iris and the vitreous body that contains the lens.

Vitreous Body (Humor)

Fluid between the lens and the retina of the eye. It is transparent and jelly-like. Supports the internal parts of the eye and maintains its shape.

Retina

Inner layer of the eye wall that contains visual receptors.

Pupil

Opening in the iris, through which light enters the eye, that regulates light. Pathway for fluid circulation from posterior chamber.

Rod Cells

Photoreceptor cells with long, thin projections that provide black and white vision. 125 million / eye. One type.

Cone Cells

Photoreceptor cells with short, blunt projections that provide color vision. 6 million / eye. Three types.

Optic Disc

Region in the retina where nerve fibers exit, becoming part of the optic nerve.

Blind Spot

Region in the visual field that corresponds to the lack of light detecting cells on the optic disc of the retina where the optic nerve passes through.

Fovea Centralis

Region of the retina consisting of densely packed cones that provides greatest visual acuity.

Anterior Cavity

Smaller cavity of the eyeball's hollow interior that is subdivided into the anterior and posterior chambers.

Posterior Cavity

The space bounded by the lens, ciliary body, and retina. It is the largest compartment of the eye and filled with vitreous humor.

Sclera

The white, fibrous outer layer of the eyeball. Protects the eye and is a strong, tough attachment for the extrinsic muscles.

Cornea

Transparent anterior portion of the outer layer of the eye wall that helps focus entering light rays.

Lens

Transparent material that strengthens visual acuity, enables the eye to focus, and is double convex.

Choroid

Vascular, pigmented middle layer of the wall of the eye. Keeps the inside of the eye dark by absorbing excess light. Nourishes blood vessels.

Aqueous Humor

Watery fluid that fills the anterior cavity of the eye and maintains the shape of the eye.