eye

eye The organ of sight. The eye has a number of components, including the cornea, iris, pupil, lens, retina, macula, optic nerve, and vitreous humor. The cornea is the clear front window of the eye that transmits and focuses light into the eye. The iris is the colored part of the eye, and regulates the amount of light that enters the eye. The size of the pupil, the dark aperture in the iris, determines how much light is let into the eye. The lens is the transparent structure inside the eye that focuses light rays onto the retina. The retina is the nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve to the brain. The macula is a small area in the retina that contains special light-sensitive cells and allows people to see fine details clearly. The optic nerve is the nerve that connects the eye to the brain. It carries the impulses formed by the retina to the visual cortex of the brain to interpret vision. The vitreous humor is a clear, jelly-like substance that fills the middle of the eye.