Eyelid

Upper and lower muscular folds of skin that move to cover and uncover the eyeball.

Cornea

Transparent front layer of the eye that covers the iris and the pupil. Provides most of the eye's optical power.

Iris

Flat, circular membrane forming the colored portion of the eye, with an adjustable circular opening, the pupil, in the center.

Pupil

Dark, circular opening in the center of the iris which varies in size to regular the amount of light reaching the retina.

Lens

Transparent, biconvex tissue that helps bring rays of light to focus on the retina.

Fovea

Small depression in the retina where visual acuity is highest.

Macula

Irregularly oval, yellow-pigmented area on the central retina that contains color-sensitive rods and the region sharpest vision acuity.

Retina

Cell layers, sensitive to light, receive images produced by the lens and triggers nerve impulses that pass via the optic nerve to the brain.

Optic Nerve

Pair or cranial nerves, consisting of sensory fibers that transmit sight impulses to the brain.

Vitreous

Transparent, gelatinous mass which fills two-thirds of the eye between the lens and the retina.