A method of making a contact lens comprising: providing first and second mold sections (152a, b), each mold section including a lens shaped surface and a flange region (161a, b) circumscribing the lens shaped surface, the first and second mold sections being structured such that when coupled together the mold sections define a lens shaped cavity between the lens shaped surface of one of the mold sections and the lens shaped surface of the other mold section and contact regions where surfaces of the flange regions of the assembled mold sections are in contact with one another; providing a polymerizable composition on the lens shaped surface of one of the mold sections; coupling together the first and second mold sections so that the flange region of the first mold section is in contact with the flange region of the second mold section; fusing the coupled mold sections between the flange regions such that the first and second mold sections are fused together along the contact regions of the interfacing flange surfaces; and causing the polymerizable composition in the lens-shaped cavity to polymerize; wherein: each flange region includes a plurality of circumferentially spaced apart recessed regions located radially outward from the lens shaped surface; and the fusing is such that the contact regions are spaced apart by gaps defined by the recessed regions, thereby forming one or more non-circumferential contact regions along the flange regions and one or more gaps separating the non-circumferential contact regions, CHARACTERISED BY allowing gases to escape from between the interfacing, unfused flange surfaces. providing first and second mold sections (152a, b), each mold section including a lens shaped surface and a flange region (161a, b) circumscribing the lens shaped surface, the first and second mold sections being structured such that when coupled together the mold sections define a lens shaped cavity between the lens shaped surface of one of the mold sections and the lens shaped surface of the other mold section and contact regions where surfaces of the flange regions of the assembled mold sections are in contact with one another; providing a polymerizable composition on the lens shaped surface of one of the mold sections; coupling together the first and second mold sections so that the flange region of the first mold section is in contact with the flange region of the second mold section; fusing the coupled mold sections between the flange regions such that the first and second mold sections are fused together along the contact regions of the interfacing flange surfaces; and causing the polymerizable composition in the lens-shaped cavity to polymerize; wherein: each flange region includes a plurality of circumferentially spaced apart recessed regions located radially outward from the lens shaped surface; and the fusing is such that the contact regions are spaced apart by gaps defined by the recessed regions, thereby forming one or more non-circumferential contact regions along the flange regions and one or more gaps separating the non-circumferential contact regions, CHARACTERISED BY allowing gases to escape from between the interfacing, unfused flange surfaces. each flange region includes a plurality of circumferentially spaced apart recessed regions located radially outward from the lens shaped surface; and the fusing is such that the contact regions are spaced apart by gaps defined by the recessed regions, thereby forming one or more non-circumferential contact regions along the flange regions and one or more gaps separating the non-circumferential contact regions, CHARACTERISED BY allowing gases to escape from between the interfacing, unfused flange surfaces.