METHOD OF DESIGNING BOTH-PLANE ASPHERICAL PROGRESSIVE REFRACTIVE POWER LENS GROUP AND BOTH-PLANE ASPHERICAL PROGRESSIVE REFRACTIVE POWER LENS GROUP

摘要

There is provided a group of bi-aspherical type progressive-power lenses for which the processing costs are reduced. In a bi-aspherical type progressive-power lens (es), the relationships DHf + DHn < DVf + DVn and DHn < DVn or further, DVn - DVf > ADD/2 and DHn - DHf < ADD/2 are satisfied; DHf and DVf are designated respectively as a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction at a far vision power measurement position F1 on a first refractive surface that acts as an object-side surface; with DHn and DVn are designated respectively as a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction at a near vision power measurement position N1 on the first refractive surface; a surface astigmatism component at F1 and N1 of the first refractive surface is canceled by a second refractive surface of the eye-side surface; and the first and second refractive surfaces are combined to provide a far vision power (Df) and an addition (ADD) on the basis of a prescription; wherein the same first refractive surface is used for at least two or more kinds of different addition power.