A person with normal vision sees objects at all distances in good focus. Near objects far objects and objects in between all appear clear and sharp. A person's eye automatically adjusts to try to maintain focus. Many people have defects of the eye that interfere with the eyes ability to adjust. In most cases of near sightedness, distant objects of pure blurry, although near objects may remain sharp. In most cases of far sightedness close objects can appear blurred, but distant objects are sharp. All objects that can be seen are either emitting or reflecting rays of light. The cornea and lens of the eye can focus these rays on light sensitive cells in the retina. Light rays from distant objects are nearly parallel. When they reach the eye. In a normal eye, the cornea and lens bend the rays toward each other just the right amount to make them come together in a clear image. The lens is relaxed and relatively thin. Light rays from near objects are still spreading outward as they reach the eye. To bring these rays close enough together to focus properly on the retina, the lens must contract to become rounder and thicker. The contracted lens bends the spreading light rays.