| 摘要 |
Toric contact or intraocular lenses having a correcting portion characterized by one or more novel constructions that each produce an optical path that improves angular misalignment tolerance. The lens (1) may be constructed with a "smooth atoric" aspect where the optical path through the correcting portion of the lens (5) corrects for both astigmatism and an axisymmetric aberration other than astigmatism, there being no sudden surface discontinuity between the regions that provide the different corrections (thus, "smooth"). In another embodiment, the lens (1) may be constructed with so-called "sectors" circumferentially arranged around the optical axis (2) such that an optical path through the correcting portion of the lens (5) varies as a function of the angular separation from the reference meridian plane (8), and the correcting portion is divided into at least two sectors (10, 11) having different astigmatism correction axes. In either embodiment, the correcting surface may be provided on either or both of the anterior(3) or posterior (4) faces of the l ens, and the optical performance of the lens in case of angular displacement (the "angular misalignment tolerance") is increased. Specifically, the angular misalignment tolerance is increased by at least 30% over a standard toric lens of the same class. Definition of the particular shape of the lens enables a mold die of that shape to be formed, or lens machining tools may be used. |
