Light Enters the Eye
Light enters the eye through the transparent front surface called the cornea (kawr nee uh). The cornea protects the eye. It also acts as a lens to help focus light rays.
After passing through the cornea, light enters the pupil, the part of the eye that looks black. The pupil is an opening through which light enters the inside of the eye. In dim light, the pupil becomes larger to allow in more light. In bright light, the pupil becomes smaller to allow in less light. After entering the pupil, the light passes through the lens. The lens is a convex lens that refracts light to form an image on the lining of your eyeball. When the cornea and the lens refract light, an upsidedown image is formed on the retina. The retina is a layer of cells that lines the inside of the eyeball. (Cells are the tiny structures that make up living things.)
The retina is made up of tiny, light-sensitive cells called rods and cones. Rods are cells that contain a pigment that responds to small amounts of light. The rods allow you to see in dim light. Cones are cells that respond to color. They may detect red light, green light, or blue light. Cones respond best in bright light. Both rods and cones help change images on the retina into signals that then travel to the brain.
A Signal Goes to the Brain
The rods and cones send signals to the brain along a short, thick nerve called the optic nerve. The optic nerve begins at the blind spot, an area of the retina so called because it has no rods or cones.
Light enters the eye through the transparent front surface called the cornea (kawr nee uh). The cornea protects the eye. It also acts as a lens to help focus light rays.
After passing through the cornea, light enters the pupil, the part of the eye that looks black. The pupil is an opening through which light enters the inside of the eye. In dim light, the pupil becomes larger to allow in more light. In bright light, the pupil becomes smaller to allow in less light. After entering the pupil, the light passes through the lens. The lens is a convex lens that refracts light to form an image on the lining of your eyeball. When the cornea and the lens refract light, an upsidedown image is formed on the retina. The retina is a layer of cells that lines the inside of the eyeball. (Cells are the tiny structures that make up living things.)
The retina is made up of tiny, light-sensitive cells called rods and cones. Rods are cells that contain a pigment that responds to small amounts of light. The rods allow you to see in dim light. Cones are cells that respond to color. They may detect red light, green light, or blue light. Cones respond best in bright light. Both rods and cones help change images on the retina into signals that then travel to the brain.
A Signal Goes to the Brain
The rods and cones send signals to the brain along a short, thick nerve called the optic nerve. The optic nerve begins at the blind spot, an area of the retina so called because it has no rods or cones.
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