Refractive Error
Refractive errors are eye disorders in which the light is not properly refracted to a point focus on the retina and instead a blurred image is perceived.
Normal Eye
Light rays enter the eye through the cornea where they are refracted (bent) and pass through the pupil to finally form a sharp focus or image on the innermost sensitive layer of the eye, the retina, just like in the camera. The retina then sends this information to the brain via the optic nerve and the brain perceives the final image. When the image is exactly formed on the retina and there is no power in the eyes, it is called Emmetropia.