What is refractive error?

Refractive error, also known as refraction error, is a problem with focusing of light on the retina due to the shape of the eye.  It generally occurs when the eye cannot focus images on the retina; the focus occurs before or after the retina. Refractive errors are corrected with eyeglasses, contact lenses, or surgery. Eyeglasses are the easiest and safest method of correction.