Anatomy of the Eye

Glossary of Terms

Anterior chamber - the region of the eye between the cornea and the lens that contains aqueous humor.

Aqueous humor - the fluid produced in the eye.

Bruch's membrane - located in the retina between the choroid and the retinal pigmented epithelium (RPE) layer; provides support to the retina and functions as the 'basement' membrane of the RPE layer.

Ciliary body - part of the eye, above the lens, that produces the aqueous humor.

Choroid - layer of the eye behind the retina, contains blood vessels that nourish the retina.

Cones - the photoreceptor nerve cells present in the macula and concentrated in the fovea (the very center of the macula); enable people to see fine detail and color.

Cornea - the outer, transparent structure at the front of the eye that covers the iris, pupil and anterior chamber; it is the eye's primary light-focusing structure.

Drusen - deposits of yellowish extra cellular waste products that accumulate within and beneath the retinal pigmented epithelium (RPE) layer.

Fovea - the pit or depression at the center of the macula that provides the greatest visual acuity.

Iris - the colored ring of tissue behind the cornea that regulates the amount of light entering the eye by adjusting the size of the pupil.

Lens - the transparent structure suspended behind the iris that helps to focus light on the retina; it primarly provides a fine-tuning adjustment to the primary focusing structure of the eye, which is the cornea.

Macula - the portion of the eye at the center of the retina that processes sharp, clear straight-ahead vision.

Optic nerve - the bundle of nerve fibers at the back of the eye that carry visual messages from the retina to the brain.

Photoreceptors - the light sensing nerve cells (rods and cones) located in the retina.

Pupil - the adjustable opening at the center of the iris through which light enters the eye.

Retina - the light sensitive layer of tissue that lines the back of the eye.

Retinal Pigmented Epithelium (RPE) - a layer of cells that protects and nourishes the retina, removes waste products, prevents new blood vessel growth into the retinal layer and absorbs light not absorbed by the photoreceptor cells; these actions prevent the scattering of the light and enhance clarity of vision.

Rods - photoreceptor nerve cells in the eyes that are sensitive to low light levels and are present in the retina, but outside the macula.

Sclera - the tough outer coat that protects the entire eyeball.

Trabecular meshwork - spongy tissue located near the cornea through which aqueous humor flows out of the eye.

Vitreous - clear jelly-like substance that fills the eye from the lens to the back of the eye.

Further Information

The following medical illustrations can provide you with more information:

• Flow of Aqueous Humor
• Build Up of Aqueous Humor
• Progression of Glaucoma Symptoms

Last Review: 04/28/13