In order for our eyes to be able to see, light rays must be bent or refracted by the cornea and the lens so they can focus on the retina, the layer of light-sensitive cells lining the back of the eye. The retina receives the picture formed by these light rays and sends the image to the brain through the optic nerve. A refractive error means that due to its shape, your eye doesn’t refract the light properly, so the image you see is blurred. Although refractive errors are called eye disorders, they are not diseases.
A myopic eye is longer than normal or has a cornea that is too steep. As a result, light rays focus in front of the retina instead of on it. Close objects look clear but distant objects appear blurred.
Hyperopia is a common type of refractive error where distant objects may be seen more clearly than objects that are near.
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.
Astigmatism is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens.
