| 摘要 |
<p>An ophthalmic lens which is a multifocal, progressive lens, has a distance viewing zone (10) and an intermediate viewing zone (14) leading to a near zone (12). The shape of a surface of the lens is defined by a final surface function such that there is no change in height at the zone boundaries (16, 18) and at least the first three derivatives of the final surface function are continuous across those boundaries. The surface of the near zone (12) is defined by a function which is the sum of the surface function of the distance zone (10) extended over the entire lens, and a near zone surface function having a factor given by a fourth degree expression in cartesian coordinates.</p> |
