Farsightedness, also known as hyperopia, is an error of refraction that initially causes difficulty in seeing near objects and then affects distance vision. It is caused by the eye being too short from front to back, so that images are not clearly focused on the retina. When blurred vision occurs, an ophthalmologist may prescribe glasses or contact lenses, with convex lenses to reinforce focusing power. A convex lens is rounded outward, like the outer surface of a globe.