Multifocal Gas Permeable Contact Lenses

contact lenses
(Contact lens) A small plastic disc containing an optical correction that is worn directly on the cornea as a substitute for eyeglasses.
A thin plastic lens placed directly on the surface of the eye to correct visual defects
(contact lens) contact: a thin curved glass or plastic lens designed to fit over the cornea in order to correct vision or to deliver medication
(contact lens) A thin lens, made of flexible or rigid plastic, that is placed directly on to the eye to correct vision, used as an alternative to spectacles, or, if coloured, to change one's eye color cosmetically

gas permeable
(of a contact lens) Allowing the diffusion of gases into and out of the cornea
(Gas permeability) is the permeability of an insulating layer for gaseous substances. The gas flow requires a difference of pressure and is characterized by the permeability coefficient (DIN 53380, DIN 535536, ISO 1399).
(Gas Permeability) the ability of a gas or other volatile substance to penetrate a material. Materials that will allow significant passage of gases are said to be permeable, while materials that resist or stop the passage of gases are said to offer gas barrier properties.
(Gas Permeability) Amount of air that can go through a lens.

multifocal
Progressive spectacle lenses, also called progressive addition lenses (PAL), progressive power lenses, graduated prescription lenses, and varifocal or multifocal lenses, are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation.
Type of spectacle lens, intraocular lens (IOL) or contact lens design that includes more than one area through which the eye focuses. such as bifocals or trifocals. Examples are bifocals or trifocals. This enables sight at multiple distances, typically for people with presbyopia.
1 : having more than one focal length 2 : arising from or occurring in more than one focus or location
Having more than one focus