| 摘要 |
To provide a bi-aspherical type progressive-power lens which provides an excellent visual acuity correction for prescription values and a wide effective visual field with less distortion in wearing, by reducing a magnification difference of an image between a distance portion and a near portion. The lens is characterized in that when on a first refractive surface being an object side surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a far vision diopter measurement position F1, are DHf and DVf respectively, and on the first refractive surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a near vision diopter measurement position N1, are DHn and DVn respectively, relational equations, DHf+DHn<DVF+DVN, and DHn<DVN are satisfied, and surface astigmatism components at F1 and N1 of the first refractive surface are cancelled by the second refractive surface being an eyeball side surface so that the first and second refractive surfaces together provide a far vision diopter (Df) and an addition diopter (ADD) based on prescription values.
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