A method comprises providing a lens blank, a precision positioning device, an illumination device, and a vision system, wherein the lens blank includes at least one feature whose position is known relative to a position of an optic center of the lens blank, and wherein the vision system comprises an image sensor and a processor； mounting the lens blank on the precision positioning device； illuminating the lens blank with the illumination device； viewing the lens blank with image sensor of the vision system； determining the position of the at least one feature using the processor； and determining the position of the optic center of the lens blank based on the position of the at least one feature using the processor.
