Nearsightedness (myopia) is a kind of disproportionate refraction, in which parallel rays of light, refracted by the optical system of the eye, gather in focus in front of the retina.
Clinical refraction characterizes the proportionality of the optical power of the eye and its anteroposterior axis (distance from the apex of the cornea to the central fovea of the retina). Clinical refraction is the position of the main focus of the eye relative to the retina.
