Myopia, hyperopia and astigmatism are different types of eye'focusing' disorders, or refractive errors. In the normal eye, light enters through the front of the eye at the cornea and is directed to a single point at the back of the eye on the retina. In a 'short-sighted' eye with a refractive error, the light is not focused to a single point at the back of the eye but in front of the retina. This is known as myopia or near-sightedness. When the light is directed to a point behind the retina, the refraction error is known as hyperopia or far-sightedness. The refractive error known as astigmatism occurs when the light is sent to two or more points either behind, in front of or on the retina.