Vocabulary- The Eye

accommodation

normal adjustment of the eye to focus on objects from far to near. when this occurs, the ciliary body adjusts the lens (rounding it) and the pupil constricts. when the eye focuses from near to far, the ciliary body flattens the lens and the pupil dilates

anterior chamber

area behind the cornea and in front of the lens and iris; it contains aqueous humor

aqueous humor

fluid produced by the ciliary body and found in the anterior chamber

biconvex

consisting of two surfaces that are rounded, elevated, and curved evenly, like part of a sphere; the lens of the eye is a biconvex body

choroid

middle, vascular layer of the eye, between the retina and the sclera

ciliary body

structure surrounding the lends that connects the iris to the choroid; it contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor

cone

photoreceptor cell in the retina that transforms light energy into a nerve impulse; are responsible for color and central vision

conjunctiva

delicate membrane lining the eyelids and covering the eyeball up to the cornea

fovea centralis

tiny pit or depression in the retina that is the region of clearest vision

fundus of the eye

posterior, inner part of the eye; visualized with an ophthalmoscope

iris

pigmented( colored) layer that opens and closes to allow more or less light into the eye;

lens

transparent biconvex body behind the pupil of the eye; it bends (reflects) light rays to bring them into focus on the retina

macula

small oval region on the retina near the optic disc; contains the fovea centralis, which is the area of the clearest vision

optic chiasm

point at which optic nerve fibers cross in the brain

optic disc

region at the back of the eye where the optic nerve meets the retina; it is the blind spot of the eye because it contains only nerve fibers, no rods, or cones, and is thus sensitive to light

optic nerve

cranial nerve carrying impulses from the retina to the brain (cerebral cortex)

pupil

central opening of the eye, surrounded by the iris, through which light rays pass; it appears dark

refraction

bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina

retina

light-sensitive nerve cell layer of the eye containing photoreceptor cells (rods and cones)

rod

photoreceptor cell of the retina essential for vision in the low light and far peripheral vision

sclera

tough, white outer coat of the eyeball

thalamus

relay center of the brain; optic nerve fibers pass through the thalamus on their way to the cerebral cortex

vitreous humor

soft jelly-like material behind the lends in the vitreous chamber; helps maintain the shape of the eyeball; often referred to as the vitreous