Soft contact lens is made of ?
PMMA
HEMA
Cellulose acetate butyrate
Vinyl monomer
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).