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| TABLE 1. PARTS OF THE EYE | | STRUCTURE | FUNCTION | | Aqueous humor | clear
watery fluid found in the anterior chamber of the eye; maintains pressure and nourishes the cornea and lens | | Vitreous
humor | clear, jelly-like fluid found in the back portion of the eye: maintains shape of the eye and attaches to the
retina | | Blind spot | small area of the retina where the optic nerve leaves the eye: any image falling
here will not be seen | | Ciliary muscles | involuntary muscles that change the lens shape to allow focusing
images of objects at different distances | | Cornea | transparent tissue covering the front of the eye:
does not have blood vessels; does have nerves | | Cones | photoreceptors responsive to color and in bright
conditions; used for fine detail | | Rods | photoreceptors responsive in low light conditions; not useful
for fine detail | | Fovea | central part of the macula that provides sharpest vision; contains only cones | | Iris | circular
band of muscles that controls the size of the pupil. The pigmentation of the iris gives "color" to the eye. Blue
eyes have the least amount of pigment; brown eyes have the most | | Lens | transparent tissue that bends
light passing through the eye: to focus light, the lens can change shape | | Macula | small central area
of the retina that provides vision for fine work and reading | | Optic nerve | bundle of over one million
axons from ganglion cells that carry visual signals from the eye to the brain | | Pupil | hole in the center
of the eye where light passes through | | Choroid | Thin tissue layer containing blood vessels, sandwiched
between the sclera and retina; also, because of the high melanocytes content, the choroid acts as a light-absorbing layer. | | Retina | layer
of tissue on the back portion of the eye that contains cells responsive to light (photoreceptors) | | Sclera | tough,
white outer covering of the eyeball; extraocular muscles attach here to move the eye |
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