Video narration
How does light become something you can actually see? Think of a camera: it focuses incoming light onto a surface, and your eye has a similar first job. Light enters through the cornea, the clear front covering that helps bend and focus it. It passes through the pupil, an opening; the iris, the colored ring around it, changes the pupil's size to control how much light gets in. The lens then fine-tunes focus, directing light onto the retina at the back of your eye, where an image forms. Tiny muscles adjust the lens's shape so you can focus on near or distant things. But your eye is living tissue, and an image on the retina is not sight. The retina turns light into signals and sends them through the optic nerve, the pathway to your brain. Your brain interprets them as sight. That is how light becomes sight.