Refractive errors occur when the shape of the eye prevents light from focusing correctly on the retina, the light-sensitive tissue at the back of the eye. Nearsightedness, also called myopia, causes distant objects to appear blurry and is increasingly common in school-age children, particularly those who spend significant time on near work or screens.
Farsightedness, or hyperopia, may cause little difficulty at distance in young children who can compensate, but it often produces eyestrain, headaches, or inward eye crossing during close work. Astigmatism, caused by an irregular curvature of the cornea or lens, creates distorted or blurred vision that glasses or contact lenses can usually correct.