Blood Vessels of the Eye reveals to visitors the tiny blood vessels that carry nourishment to their retinas. Even though these vessels are always in your field of vision, you normally don’t see them because the brain, coupled with fatigue of the eye’s receptor cells, eliminates them from view. In this exhibit, visitors press a small penlight against their closed eyelid and move it around. Any light entering the eye must pass through the blood vessels to reach the retina. Dark reddish lines (like tree branches) that are actually the shadows of the eye's blood vessels.