Regional Optimal Design of Astigmatism for Progressive Addition Lenses
A regional optimization design method is proposed to reduce the astigmatism of progressive addition lenses(PAL).This method is used to optimize the near vision and astigmatic zones of PAL.First,the least squares method is used to find the spherical patch that best fits the superposed region.Subsequently,the progressive surface and spherical patch are combined proportionally to reduce the astigmatism of PAL.Finally,the Zernike polynomial regional fitting method is used to smooth the lens surface at the boundary of the superposed region,thereby reducing unnecessary astigmatism due to surface mutations.The test results of the initial design and optimized lens samples demonstrate that the maximum astigmatism of PAL after optimization decreases by 14.3%,area of maximum astigmatism decreases by 30.5%,and range with astigmatism less than 0.06 D in the near vision area increases by 30.4%.This optimization design method significantly reduces astigmatism while maintaining a relatively unchanged focal power distribution,expanding the effective visual range in near vision areas and improving visual experience for wearers.
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