Normal vision (emmetropia)

In the eye with normal vision, clear images are formed on the retina. The optical system of the eye (cornea, lens and vitreous body) deviates incoming light rays so that they are brought to a focus exactly on the visual center (macula) of the retina. If this is not the case, a blurred image is formed – this is called an error of refraction or ametropia. Today, most errors of refraction can be successfully treated by refractive surgery.