Rigid

A rigid lens is able to replace the natural shape of the cornea with a new refracting surface. This means that a spherical rigid contact lens can correct for astigmatism. Rigid lenses can also be made as a front-toric, back-toric, or bitoric. This is different from a spherical lens in that one or both surfaces of the lens deliver a toric correction. Rigid lenses can also correct for corneal irregularities, such as keratoconus. In most cases, patients with keratoconus see better through rigid contact lenses than through glasses. Rigid lenses are more chemically inert, allowing them to be worn in more challenging environments than soft lenses.