Anatomy of the Eye

Cornea

Window of the eye, transparent part that covers the iris and pupil

Sclera

Tough, white outer layer of the eyeball, provides protects and helps maintain eye shape

Iris

Controls the amount of light entering the eye, enough to allow a person to see, too much would damage the retina

Pupil

Hole in the middle where light continues its passage to the retina

Lens

Located BEHIND the pupil, helps bring light rays into focus on the retina; absence of lens reduces clarity of focus

Ciliary Body

Controls accommodation, changing lens shape to focus on near and distance vision

Ciliary Muscle

Located behind the ciliary body, helps hold the lens in place

Retina

Inner sensory nerve layer next to the choroid. Reacts to light and transmits electrical impulses to the brain. Photosensitive

Macula

Responsible for central vision

Fovea

Responsible for good visual acuity

Optic Nerve

Transmits visual information from the retina to the brain

Suspensory Ligament (Zonules of Zinn)

Helps hold the lens in position/place and allos it to change shape

Choroid

Nourishes the retina with oxygen and blood

Vitreous Humor

Hollow cavity filled with a jelly-like substance between the lens and the retina helps the eye maintain its shape of the posterior part of the eye

Aqueous Humor

Maintains the shape of the eyeball, maintains outside shape

Anterior Chamber

Filled with aqueous humor in the front of the eye

Posterior Chamber

Filled with vitreous humor in the back of the eye

Rods

Night/Low light vision and peripheral

Cones

Color, Contrast, Clarity

Hyperopic

Farsighted and Convex lens (+)

Myopia

Nearsighted and Corrective lens (-)

Emmetropic

Normal eyes

Eso

In

Exo

Out

Hyper

Up

Hypo

Down

Tropic/tropia

marked deviation; typically there

Phoric/phoria

A tendency; after a while

Legal Blindness

Visual acuity of 20/200 or worse in the better eye with the best correction and a visual field of 20 degress or less in the better eye