Contour prism lens with progressive power
A contour prism progressive lens has a position dependent optical power and a position dependent horizontal prism, and a distance-vision reference point and a near-vision reference point. It is characterized by a coordinate system with its vertical axis running through the distance-vision reference point and has an optical power at the near-vision power reference point that exceeds the optical power at the distance-vision reference point by a value between 0.25 diopter and 1.0 diopter. The horizontal prism on the vertical axis at a vertical coordinate of the near-vision reference point differs from the horizontal prism at the distance-vision reference point by more than 0.2 prism diopter base-in; and the optical power along a horizontal crosscut of the contour prism progressive lens through the near-vision reference point has a broad maximum where the region where the optical power is at least 85% of its peak is at least 5 mm wide.
1 . A contour prism progressive lens, having a position dependent optical power and a position dependent horizontal prism, and having a distance-vision reference point and a near-vision reference point, the contour prism progressive lens being characterized by a coordinate system with its vertical axis running through the distance-vision reference point, wherein:
the optical power at the near-vision power reference point exceeds the optical power at the distance-vision reference point by a value between 1.0 diopter and 2.5 diopters;
the horizontal prism on the vertical axis at a vertical coordinate of the near-vision reference point differs from the horizontal prism at the distance-vision reference point by more than 0.2 prism diopter base-in; and
the optical power along a horizontal crosscut of the contour prism progressive lens through the near-vision reference point has a broad peak where the region where the optical power is at least 85% of its peak value is at least 8 mm wide; wherein
the horizontal crosscut is oriented laterally in the coordinate system.
2 . The contour prism progressive lens of claim 1 , wherein:
the optical power along a horizontal crosscut of the contour prism progressive lens through the near-vision reference point has a broad peak where the region where the optical power is at least 85% of its peak value is at least 10 mm wide.
3 . The contour prism progressive lens of claim 1 , wherein:
the optical power along a horizontal crosscut of the contour prism progressive lens through the near-vision reference point has a peak where the region where the optical power is at least 75% of its peak value is at least 10 mm wide.
4 . The contour prism progressive lens of claim 1 , wherein:
the optical power along a horizontal crosscut of the contour prism progressive lens through the near-vision reference point has a peak where the region where the optical power is at least 75% of its peak value is at least 12 mm wide.
5 . The contour prism progressive lens of claim 1 , wherein:
a magnitude of a horizontal derivative of the optical power along the horizontal crosscut of the contour prism progressive lens through the near-vision reference point is less than 0.1 diopter/mm over a region more than 5 mm long, comprising the near-vision reference point.
6 . The contour prism progressive lens of claim 1 , wherein:
a magnitude of a horizontal derivative of the optical power along the horizontal crosscut of the contour prism progressive lens through the near-vision reference point is less than 0.1 diopter/mm over a region at least 7 mm long, comprising the near-vision reference point.
7 . The contour prism progressive lens of claim 1 , wherein:
a magnitude of a horizontal derivative of the optical power along the horizontal crosscut of the contour prism progressive lens through the near-vision reference point is less than 0.05 diopter/mm at the near-vision reference point.
8 . The contour prism progressive lens of claim 1 , wherein:
a magnitude of a horizontal derivative of the optical power along the horizontal crosscut of the contour prism progressive lens through the near-vision reference point is less than 0.03 diopter/mm at the near-vision reference point.