Patent ID: 6712467
Filing Date: 2004-03-30
Classification: G02C

Abstract:
Progressive-power lens groups comprising at least one group for correcting hyperopia and at least one group for correcting myopia wherein for each lens of the lens groups, said lens comprises:a distance portion formed in the upper region of the lens; a near portion formed in the lower region of the lens; and an intermediate portion formed in an intermediate region between said distance portion and near portion; said lens having a refractive power distribution in which the refractive power of each portion changes progressively going from said distance portion through the intermediate portion to the near portion along a principal sight line that is a center reference line dividing the lens into substantially left and right portions; and said lens having a predetermined range of addition; and said distance portion corresponding to the prescription for correcting hyperopia or that for correcting myopia, wherein: when said lens is for correcting hyperopia, said distance portion has a positive refractive power, and correction is made by optimizing transmission astigmatism parameters so as to minimize the transmission astigmatism at each point on said principal sight line; and when said lens is for correcting myopia, said distance portion has a negative refractive power, and correction is made by optimizing transmission average refractive power error parameters so as to minimize the transmission average refractive power error at each point on said principal sight line.