Just imagine what life was like for millions of people before eyeglasses were invented! If you were near-sighted and you looked up at night you couldn’t see the stars. You couldn’t see clouds or distant mountains, or birds flying through the air.

Today near-sighted people can see as much as people with normal eyes, because eyeglasses can correct their vision. To begin very simply, we can see because light enters our eye and falls on the retina in the eye, which is like the sensitized plate of a camera. Obviously, if the light falls in back of the retina or in front of it, we won’t be able to see. So the eye has a lens to focus the light and make it fall in the right place.