Oxygen permeability

Overview
Oxygen permeability, abbreviated Dk, is a parameter of a contact lens. Another parameter, the transmissibility level, abbreviated  DK/t; the Dk per thickness of the lens, is generally more used. Typical values are from 25 to 50. The Oxygen permeability expresses the ability of the lens to let oxygen reach the eye by diffusion. In soft contact lenses, it is dependent on the thickness of the lens and the material of the lens, especially concerning the water content.