Rigid gas permeable lenses are rigid contact lenses made of oxygen-permeable polymers. Initially developed in the late 1970s, and through the 1980s and 1990s, they were an improvement over prior 'hard' lenses that restricted oxygen transmission to the eye.
Rigid lenses are able to replace the natural shape of the cornea with a new refracting surface. This means that a regular (spherical) rigid contact lens can provide good level of vision in people who have astigmatism or distorted corneal shapes as with keratoconus. However, they require a period of adaptation before full comfort is achieved.
Famous quotes containing the words rigid and/or gas:
“During our twenties...we act toward the new adulthood the way sociologists tell us new waves of immigrants acted on becoming Americans: we adopt the host culture’s values in an exaggerated and rigid fashion until we can rethink them and make them our own. Our idea of what adults are and what we’re supposed to be is composed of outdated childhood concepts brought forward.”
—Roger Gould (20th century)
“Man moves in all modes, by legs of horses, by wings of winds, by steam, by gas of balloon, by electricity, and stands on tiptoe threatening to hunt the eagle in his own element.”
—Ralph Waldo Emerson (1803–1882)