| 摘要 |
A progressive multifocal ophthalmic lens having a refractive lens surface divided into a far vision viewing zone, an intermediate viewing zone and a near vision viewing zone and defining a substantially vertical principal meridian curve. The optical center of the far vision viewing zone is at the lower end of the principal meridian curve in the far vision viewing zone and an optical center of the near vision viewing zone is at the upper end of the principal meridian curve in the near vision viewing zone. The curvature of the principal meridian curve changes between the optical center of the far vision viewing zone and the optical center of the near vision viewing zone in accordance with a prescribed law to define the additional power of the lens. At each point on the principal meridian curve in at least one of the far vision viewing zone and near vision viewing zone, the difference between the curvature along the principal meridian curve and the curvature along the vertical direction with respect to the principal meridian curve at each point on the principal meridian curve is not zero in any part of the at least one zone.
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