When light enters the eye it first enters through your cornea, the transparent protective coating over your eye. Next it will pass through the pupil which is the small opening in the middle of your iris, or colored part of your eye. The muscles in the iris help to protect the eye by expanding and contacting based on the brightness of the light in your environment helping you see much clearer in bright and dim light. In side the pupil the light will then move through the lens which focuses the light and displays and image onto the retina, the light-sensitive inner lining of the back of the eyeball. …