Refractive Error

Nearsightedness (Myopia) is a condition in which the length of the eye is longer and the cornea is steeper, causing the light rays to fall in front of the retina.
Farsightedness (Hyperopia) is a condition in which the light rays fall behind the retina and the cornea is too flat.
Astigmatism is caused by the irregular curvature of the front surface of the eye (cornea).