| 摘要 |
An ophthalmic lens having a progressively variable refracting power, includes a portion for distance vision which has a refracting power of a far scene along a principal meridional curve, a portion for near vision which has a refracting power of a near scene, and an intermediate portion defined between the portions for distance vision and near vision to connect these portions by continuously changing refracting power. Changes in curvature rho m along the principal meridional curve and curvature rho s along a direction perpendicular thereto are optimized on the principal meridional curve, thereby detecting an optimal shape. The curvature rho m along the principal meridional curve and the curvature rho s in a direction perpendicular to the principal meridional curve are maximum in an upper position in the portion for near vision on the principal meridional curve, decreased toward a periphery of the portion for near vision along the principal meridional curve, substantially satisfy condition rho m= rho s in an area from at least a lower position in the portion for distance vision to almost the center of the intermediate portion, and satisfy condition ¦ rho m- rho s¦ NOTEQUAL 0 in the area from the center of the intermediate portion to the portion for near vision. The ophthalmic lens has a shape which satisfies the above requirements.
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