Optically normal eye (Emmetropia) can be defined as a state of refraction, where in the parallel rays of light coming from infinity are focused at the sensitive layer of retina with the accommodation being at rest.A condition of refractive error (Ametropia) is defined as a state of refraction, when the parallel rays of light coming from infinity (with accommodation at rest), are focused either in front or behind the sensitive layer of retina, in one or both the meridians.
The refractive error includes
1.Myopia
3.Astigmatism.
