refraction (Rfx)

The deflection in electromagnetic radiation (light) when it passes from one medium to another of different optical density. In passing from a medium of greater optical density to one of less optical density the light is deflected away from a line perpendicular to the surface of the refracting medium. In passing in the reverse direction, it is deflected towards this perpendicular line. The diopter is the unit of refracting power of lenses.

Related

diopter (D) refractive error; ametropia refractive index

References

Stedman's Medical Dictionary 27th ed, Williams & Wilkins, Baltimore, 1999