Lens blocking and constant center thickness system

A blocking member for mounting a lens blank in which a posterior surface a contact lens or intraocular lens and an annular reference surface at a known depth surrounding said posterior surface have been formed including:

• a central portion having a forward surface and a rearward surface;
• a spindle engaging member rigidly connected to and extending rearward from said central portion;
• a lens blank support member having a front curved surface complementary to and axially located on said posterior surface, extending forward from and separable from said forward surface;
• means for securing said lens blank support member to said forward surface during shaping of the front surface of the lens blank including a cavity formed in said forward surface and shaft means connected to the rear of the lens blank support member, a second end received in said cavity, said shaft means including means for fixedly securing said shaft in said cavity;
• and
• said shaft means including a cylindrical side wall between said front curved surface and the forward surface of the central portion having a diameter smaller than the forward surface whereby an annular portion of the forward surface surrounds said cylindrical side wall and further including a cylindrical ring formed of synthetic resin, having a first end wall and a second end wall, said ring being snugly received on said side wall with the first end wall being seated on the annular portion of the forward surface of the central portion and the second end wall, said side wall having a height less than said ring And said second end wall, said side wall and curved surface of the lens blank support member forming a cavity for receiving the posterior surface of the lens blank and said second end wall in complementary to and engaging said annular reference surface of the lens blank when said blank is mounted on said blocking member.