| 摘要 |
A progressive multifocal ophthalmic lens having a far vision region, an intermediate vision region and a near vision region, a main meridian of progression passing through said three regions, and a power addition equal to a difference in mean sphere between a near vision region control point and a far vision region control point is provided. The lens has a progression length less than 12 mm, defined as the vertical distance between a mounting center and a point on the meridian where mean sphere is greater than mean sphere at the far vision control point by 85% of the power addition value. To ensure good visual characteristics not only around the meridian, but also in regions of extra-foveal vision, the ratio between the integral of the product of cylinder times the norm of sphere gradient, on a 40 mm diameter circle centered on the center of the lens, and the product of the area of this circle, power addition and a maximum value of the norm of sphere gradient over that part of the meridian comprised within this circle is less than 0.14.
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