Short-sightedness. Illustration of a cross section of an eye with short-sightedness. In short-sightedness, or myopia, the eyeball is longer than it should be, or the eye's lens (grey) is the wrong shape, and light (blue lines) is focussed in front of the retina. This causes difficulty focussing on a distant object (O), which appears blurred. It can be corrected by placing a concave lens in front of the eye.