In a normal eye, light rays project an image directly ON your retina. But if the eye is too long, or if the cornea bends light rays too much, then the image is focused in FRONT of the retina. In this case, the person is said to have myopia, or near-sightedness, which means they can see clearly up close, but need corrective lenses to see clearly at a distance. Corrective lenses bend the light in a way that causes it to be focused directly onto the retina again.