<prompt> Soft contact lens is made of ?PMMAHEMACellulose acetate butyrateVinyl monomer  <response>: Ans. is b i.e., HEMA Types of contact lenses Depending upon the nature of the material used in their manufacturing, the contact lenses can be divided into three types : - i Hard lenses : - Made of polymethylmethacrylate PMMA. ii Rigid gas permeable RGP lenses : - Copolymer of PMMA, silicon containing vinyl monomer and cellulose acetate butyrate CAB are used to manufacture RGP lenses. iii Soft lenses : - These are made up of hydroxymethymethacrylate HEMA. 