Method for manufacturing toric contact lenses

A method for manufacturing a toric contact lens, the method comprising the steps of:

• a. Injection molding to form an anterior mold section and a posterior mold section, wherein the posterior mold section or the anterior mold section has a toric portion and the other mold section has a prism ballast, wherein each mold has a tab or other locating features for facilitating a determination of orientation of the mold,
• b. measuring a cylinder axis angle error of the mold section having the toric portion by an interferometer apparatus, wherein the cylinder axis angle error is defined as a difference of measured cylinder axis angle by the interferometer apparatus and a reference cylinder axis angle defined by the tab position or other locating features,
• c. determining an actual amount of rotation angle by subtracting the cylinder axis angle error from a target axis angle,
• d. rotating one of the mold sections by the actual amount of rotation angle, while the other molding section is not rotated,
• e. introducing a lens forming material into the mold section being rotated or the other mold section being not rotated after step d of rotating one of the mold sections,
• f. assembling the anterior mold section and the posterior mold section to form a lens shaped cavity there between,
• g. curing the lens forming material in the lens shape cavity to form the toric lens.