Transmissibility of contact lenses
In the atmosphere there is 20.9% of oxygen. The cornea is an avascular tissue and needs the oxygen of the atmosphere to be able to perform its physiological functions. With what reaches it through the limb vessels and the aquaous humour is not enough.
For this reason, when a person is a contact lens user it is very important that they let the oxygen pass through. This is done through the mechanisms of diffusion (measured as how fast the oxygen passes through the material) and the solubility (measured as how much oxygen contains the material).
The transmissibility is the value that results from studying the diffusion and solubility of a material taking into account its thickness. That is, the slimmer a contact lens is, the better transmissibility.
The current materials of silicone hydrogel and the semi-rigid permeable gas lens meet the physiological demands of the cornea.