| 摘要 |
Methods for determining a progressive ophthalmic lens are described, the lens comprising a near and a far vision area, a main meridian separating the lens into a nasal and a temporal area. The method includes determining a first and a second surface of the lens, determining the second surface to provide, in combination with the first surface, vision correcting properties, and determining a spherical area on the first surface of the lens having a constant sphere value and including a far vision diopter measurement position. The far vision diopter measurement position and a near vision diopter measurement position have substantially the same mean sphere value. The method also includes determining the first surface to reduce the lens distortion by defining a toric area extending outside the spherical area on the first surface in at least one of the nasal and the temporal area, in which characteristics of the toric area are related to the lens astigmatism. |
| 主权项 |
1. A method implemented by computer means, for determining a progressive ophthalmic lens with vision correcting properties related to a prescription of an individual wearer and enabling reduction of lens distortion of a lens, the lens to comprise a near vision area, a far vision area, and a main meridian separating the lens into a nasal area and a temporal area, the method comprising:
providing a misalignment error (Tx) in an X axis direction of the lens due to a manufacturing process to be used to manufacture the lens, providing a misalignment error (Ty) in a Y axis direction of the lens due to the manufacturing process to be used to manufacture the lens, determining a first surface and a second surface of the lens; determining the second surface to provide, in combination with the first surface, all vision correcting properties related to the prescription of the individual wearer; determining a spherical area on the first surface of the lens having a substantially constant sphere value, and including within the spherical area a far vision diopter measurement position of the individual wearer, the far vision diopter measurement position (“FV position”) and a near vision diopter measurement position (“NV position”) of the individual wearer having substantially a same mean sphere value; and determining the first surface to reduce the lens distortion by defining a toric area extending outside the spherical area on the first surface in at least one of the nasal area and the temporal area, such that characteristics of the toric area are related to astigmatism, the spherical area having a first part and a second part, with the first part including the FV position and the second part including the NV position, said first part being separated from or continuous with the second part, the size of each of the first part and the second part of the spherical area being defined by a reference width ‘a’ and a reference height ‘b’, the FV or NV position being centered at its respective part of the spherical area defined by the reference distance ‘a’ and the reference distance ‘b’, whereby for the first part of the spherical area including the FV position, the reference distance ‘a’ is set to be greater than two times the misalignment error (Tx) in the X axis direction of the lens due to the manufacturing process, and the reference distance ‘b’ is set to be greater than two times the misalignment error (Ty) in the Y axis direction of the lens due to the manufacturing process, and for the second part of the spherical area including the NV position, the reference distance ‘a’ is greater than two times the misalignment error (Tx), and the reference distance ‘b’ is greater than two times the misalignment error (Ty). |
