A group of visual disorders due to refractive errors where light rays fail to focus on the retina leading to blurry vision. One of these disorders is myopia where the eye has excess power or is too long such that a point at infinity focuses in front of the retina. Hyperopia (far-sightedness) presents with weak eye power or a very short eyeball; hence a point at infinity focuses behind the retina. In astigmatism, refractive error changes with the meridian. All three conditions need glasses or contact lenses to refocus the incoming light.