Astigmatism is an eye condition that affects a high percentage of the population. It results from an imperfect curvature of eye that causes refractive error. This means that, when light enters the eye, it is not focused evenly onto the retina. Instead, it is focused either in front of or behind the retina, often resulting in blurred vision.
Hyperopia, also known as farsightedness, is a condition of the eyes in which distant objects appear in clearer focus than do objects closer to the eye. As a result, nearby objects appear blurry. The eye is designed to focus images directly on the surface of the retina; with hyperopia, light rays focus behind the surface of the retina, producing a blurred image. Hyperopia occurs if the eyeball is abnormally short, the cornea has too little curvature, or the lens is situated too far back in the eye.
Myopia, also known as nearsightedness or shortsightedness, is a condition of the eyes in which nearby objects are clear and distant objects appear blurred. Almost a third of people in the United States experience some degree of nearsightedness.