Nearsightedness (myopia), farsightedness (hypermetropia) and astigmatism are types of refractive errors, flaws that keep the eye from focusing light sharply on the retina. Fortunately, spectacles are all that are needed to focus the light to give a plain image and allow us to read and see clearly. Other alternatives include contact lenses and refractive surgery.
A short sided (or myopic) person has better near vision over far vision without glasses. A long-sighted (or hypertrophic) person has better far vision then near without glasses. With astigmatism, there is a blend of different magnitudes of refractive error in different clock orientations so that a lens to correct astigmatism has to have an appropriate orientation, whether it be by glasses, contact lenses, intraocular lenses or corneal refractive surgery.
In children, it is important to correct refractive errors early, to allow the brain to learn to use the image from each eye properly and to learn to merge the images from the two eyes to develop binocular vision and depth perception (link to children’s eye conditions)
In adults, surgery offers the promise, in suitable patients, of freedom from spectacles, either full-time or part-time.(link to refractive surgery).