Light follows a complex, but not very long path from the cornea to the brain. First, of course, light hits the cornea, or the transparent section of the eye joined with the sclera. The sclera is the hard white section of the eye. Just beneath the cornea are two more sections: the iris and the pupil. The pupil is the hole through which light travels into the eye. The iris is the colored ring around it. The iris and other ligaments, or muscles, expand or contract the iris, varying the amount of light that enters. The light has now passed through all of the visible sectors of the eye and is now inside.
After the pupil is the lens. The lens is what focuses the light. Lenses are found everywhere and there are two main types: convex and concave. Convex lenses refract the beams closer to each other so each one eventually crosses in a focal point. Concave lenses refract the beams away from each other and never create a focal point. The lens in our eye is a convex lens. After the beams pass through the lens, they hit the retina, a section of light-sensitive cells. The image is then reflected along the optic nerve to the brain. Unfortunately, the image is upside down, because of the crossing, so the brain has to flip the image to make everything look right.
After the pupil is the lens. The lens is what focuses the light. Lenses are found everywhere and there are two main types: convex and concave. Convex lenses refract the beams closer to each other so each one eventually crosses in a focal point. Concave lenses refract the beams away from each other and never create a focal point. The lens in our eye is a convex lens. After the beams pass through the lens, they hit the retina, a section of light-sensitive cells. The image is then reflected along the optic nerve to the brain. Unfortunately, the image is upside down, because of the crossing, so the brain has to flip the image to make everything look right.
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