Molds for use in contact lens production

A mold for the production of a contact lens comprising a front mold half and a back mold half wherein:

• the front mold half comprises a first article having a central curved section with a concave surface, a convex surface and a circular circumferential edge, the central section of the concave surface suitable for imparting a curvature to the front curve of a contact lens;
• the first article also having an axis of symmetry about the concave surface, and an inner mating surface continuous with and extending outwardly from the circular edge in a plane about 5 to about 15 degrees below a plane normal to the concave surface axis of symmetry, an annular groove extending around the periphery of the inner mating surface, an outwardly tapering front wall extending upwardly from the annular groove, and an annular flange integral with and surrounding the outwardly tapering wall and extending radially outwardly from the concave and convex surfaces in a plane normal to the concave surface axis;
• the back mold half comprises a second article having a central curved section with a concave surface and a convex surface, the central section of the convex surface suitable for imparting a curvature to the back curve of a contact lens;
• and
• the second article also having an axis of symmetry about the convex surface, a shoulder extending outwardly from the convex surface, a fillet having a radius of curvature of about 10 μm to about 250 μm forming the junction between the outwardly extending shoulder and the convex surface, an outwardly tapering wall continuous with the shoulder and extending upwardly therefrom, and an annular flange integral with and surrounding the outwardly tapering wall and extending radially outwardly from the concave and convex surfaces in a plane normal to the convex surface axis.