Now, just like the pupil can basically be controlled, the length can also be controlled by a set of smooth muscles known as the ciliary muscles found inside our section shown here. Now, the ciliary muscles are controlled by the autonomic system. And basically, by changing the shape of our lens, we're essentially changing the focal length of that lens. And that allows us to focus our image onto our retina at the back of our eyes. So remember, from physics, we should know that because the lens is a convex lens, that basically creates a real image found on the back of the eye on the retina. And that image is upside down, it's inverted.