| 摘要 |
An object of the present invention is to improve the optical state of a progressive addition lens along a principal line of vision through which the line-of-sight of a wearer passes by making the displacement of a position at which the optical state on particularly the front near vision becomes the best to be the same as the amount of inward movement of line-of-sight, when the wearer moves his (or her) line-of-sight from the front far distance to the front near distance
an expression OI < DH is satisfied when: the principal line of vision L is an intersecting line of the line-of-sight of the wearer of the progressive addition lens from the distance vision to the near vision and a refractive surface of the progressive addition lens; a point F and a point ON in the principal line of vision respectively represent a position corresponding to the front distance vision of the wearer of the progressive addition lens and a position corresponding to the front near vision of the wearer of the progressive addition lens; the amount of inward movement of line-of-sight or represents a displacement of the point ON from the point F toward the nose side in the horizontal direction; a point DN is an intersection of a profile curve in horizontal direction H and a principal meridian curve M, in which the profile curve in horizontal direction H passes through the point ON and the principal meridian curve M passes through the point F of the front distance vision; and an amount of design inward movement DH is a displacement of the point DN from the point F toward the nose side in the horizontal direction.
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