For proper vision, light must travel through the cornea and the eye’s lens, with rays converging at a point on the retina. Sometimes, eyes have irregularities that keep light from converging (focusing) where it should. When light is deflected to a different point, it is known as a refractive vision problem. The majority of people who cannot see clearly have refractive vision problems. This means that light may focus either in front of the retina (resulting in nearsightedness or myopia) or behind the retina (which results in farsightedness or hyperopia). In some cases, light does not focus at a single spot, which blurs all images (which occurs in astigmatism). Refractive vision problems are managed by using an artificial lens to bend light, bending light rays to the proper place. Most people with myopia, hyperopia, or astigmatism have used eyeglasses or contact lenses to bend light so that vision is clear and sharp. Other therapies can provide clear vision without using glasses or contact lenses, or with reduced need for them.
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