Poly(methyl methacrylate)

Perspex is the name given to the polymer of methyl methacrylate; the material is thermoplastic, and transparent.

It is often used in place of glass, though its softness leads to its being easily scratched. The material has a good degree of compatibilty with human tissue, and can be used for replacement lenses in the eye when the original lens has been removed in the treatment of cataracts. Hard contact lenses are frequently made of this material; soft contact lenses are often made of a related polymer, in which the acrylate monomers are used that contain one or more hydroxy groups to make them hydrophilic