Another way of putting spectacles on a diet is to use what is known as aspheric grinding: In the case of conventional ground lenses – referred to in the trade as spherical lenses – the front and back surfaces of the lens are curved like a sphere. In contrast, aspheric lenses feature specially optimised surfaces. In order to avoid a pronounced, aesthetically unappealing curvature of the front surface of the lens while simultaneously achieving perfect visual quality, the front surface of an aspheric spectacle lens is optimised so that the surface flattens out from the center of the lens toward the edges. This makes it possible to make aspheric lenses thinner and significantly lighter while maintaining the same optical effect. In combination with the ZEISS high-index lens materials referred to above, aspheric lens design techniques can be used to create flat, thin and extraordinarily lightweight spectacle lenses – even for wearers with significant vision problems.
Another method of producing ultra-thin lenses is to use a computer-assisted method developed by ZEISS called OPTIMA. This makes it possible to reduce the edge and center thickness visible in the frame to a minimum at the production stage while taking all the frame specifications into account. Often OPTIMA enables the lens to be produced much more thinly. The eye care professional can use special recommendation programs from ZEISS to visualize these thickness differences.