In the production of progressive lenses, a special freeform generator transfers the newly computed power design to the semi-finished lenses or casting dies.
Complex production trials are required to manufacture the first usable prototypes: the entire progressive surface is measured using special measuring machines, allowing adjustment of the measured values to the mathematical data of the specified progressive surface. Not until this often difficult adjustment procedure is complete is it possible to obtain the first usable prototypes for wearing trials.
In wearing trials it is possible to test the degree of wearer tolerance for the new progressive. If the tolerance rate for the new lens is low, the design is modified and the development cycle starts from the beginning again.