Trifocal spectacle lens with cosmetic appearance - where there is no distortion of vertical lines viewed through the lens

摘要

A multifocus spectacle lens, esp. a trifocal lens uses a vertical meridional curve (C) dividing the lens into two halves and forming three horizontal zones with no unsightly jumps in the curve (C). The top zone is for viewing distant objects, whereas the other two zones are subdivided along their widths into =3 parts, curve (C) running down the centre of the middle part, the other parts being aspherical. The surface of each outer side part forms part of a surface of revolution with a vertical axis of rotation in the main meridional plane. A lens with a cosmetic appearance, and where observed vertical lines seen through the lens are unbroken over the entire field of view.