People use glasses or contact lenses for the same reason.
Click here to view all the video clips Myopia or nearsightedness - With myopia or nearsightedness, the curvature of the cornea is too steep. This causes light to focus in front of where it should, so the image on the retina is blurred. Hyperopia or farsightedness - With hyperopia or farsightedness, the shape of the eye causes light to focus too far back in the eye, behind the retina. Onset typically occurs between 40 and 45 years of age. Prior to that age, the lens moves to keep objects in focus as they get closer to the eye.