improved contact lens compositions are achieved through incorporation of a fluorine containing mono or diester of itaconic acid in siloxane polymeric contact lens compositions . copolymers include components which modify contact lens mechanical , optical and transport properties as well as surface characteristics to achieve at least some compositions having an oxygen permeability of at least dk35 with a refractive index of from 1 . 35 to 1 . 5 and a percent hydration below 2 percent of total weight . contact lenses made of materials of this invention are highly permeable to oxygen and resistant to the deposition of tear components providing extended wear capability through improved biocompatibility .