The Surface Design
The special benefit of ZEISS Single Vision Aphal 1.5 lenses is their aspheric front surface specially designed for high plus powers. It features a curved continuous transition zone between the aperture and the flattened margin (flattened margin asphere).
The aspheric surface design of the aperture provides the excellent visual quality also associated with the aspheric design of ZEISS single vision lenses.
Benefits of the Aspheric Design
The special aspheric design also makes the lens flatter. This reduces the "shape factor" or effective magnification of the lens, i. e. the wearer’s eyes look less magnified. Apart from its optical and cosmetic benefits, the asphere also results in a weight reduction compared to ZEISS Single Vision Sph 1.5 or glass lenses and hence also in enhanced wearing comfort. The thinner marginal zone allows standard frames to be glazed without difficulty.