Optimization method for freeform progressive addition lenses using the coincident degree of weight distributions for power deviation and astigmatism

Abstract This study proposed an optimization method for freeform progressive addition lenses (PALs) based on the coincident degree of weight distributions (WD) for power deviation and astigmatism. Compared with the existing methods which were limited in optimizing WDs for power deviation and astigmatism, our proposed approach offers a more refined optimization. In the design phase, the power deviation and astigmatism of these lenses were evaluated using the existing surface shape. Compared with the prescriptions of the patients, the coincident degrees between the obtained distributions and prescriptions of the PAL power and astigmatism were calculated in the multi-view axis condition. Normalization processing of coincident degrees was performed, yielding the corresponding threshold value of WDs and optimizing the allocated coincident degrees. Based on a minimization error function model, two PALs were designed, simulated, machined, and evaluated using a commercial software. The optimized method reduced peripheral astigmatism and improved the optical properties of PALs. The proposed approach optimizes the freeform PALs and enhances their design optimization in optometry.