These are long-life lenses that can be worn for up to a year, as long as they are removed each evening prior to going to bed. These gas permeable contacts are available both as soft or rigid lenses and require regular cleaning as well as sterilising.
The history of the contact lens dates all the way back to the 17th Century, but it took several hundred years before they could be put to practical use. It was not before 1971, that the first gas permeable lens came out on the market. It permits the eye to continue "breathing" oxygen - a pre-requisite for comfortable contact lens wear. The first gas permeable lenses were made from a compound known as hydrogel, although today there are both soft and hard lenses which are oxygen permeable.
Rigid gas permeable contact lenses admit oxygen to the eye while providing enhanced visual accuracy and improved ease of handling when it comes to extraction and insertion of the vial lenses. At the beginning of the 80s, a number of new inventions were introduced, including tinted lenses, extended-wear vial lenses and bi-focal lenses.