vision components
When light within the visible spectrum contacts the human eye, it first passes through the cornea, a transparent covering which assists in focusing the eye. The "white" of the eye is actually the sclera, or the whitish protective outer coating of the eye. The amount of light is regulated by the iris, or colored part of the eye, which contracts or expands to allow light in or restrict it. In the center of the iris is the pupil, which is the opening in the iris, through which the light passes. After that it comes into contact with the lens, another transparent covering which helps focus the eye, in a fashion similar to the cornea. However, the lens, with the assistance of muscles in the eye, can shift and change the focus of the eye to different areas, in a process known as accomodation.
In the retina, the large portion of the eye, are the rods and cones, photoreceptors which absorb the light. Both work similarly, though the rods are specifically meant for monochromatic purposes and the cones for color vision. Visual information passes from the rods and cones to bipolar cells, which then pass it to ganglion cells, which carry it to the brain.
