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

摘要

The spectacle lenses are shaped such that they are curved "concave" as seen from the wearer, and are thicker at the centre than the edges. The refractive index of the glass that is used to make objectives is arranged to vary in a defined manner from the centre point, to the edges of the lens. Thus, an extremely high dioptre lens may be made.