Varifocal contact lenses work by having multiple prescriptions in a single lens, similarly to a varifocal spectacle lens; there’s one for close objects, one for objects viewed at a distance and one for intermediate.
There are two ways in which these different prescriptions are incorporated into a lens. The design most often fitted uses a set of concentric circles, each with its own a distinct lens power. The second blends these circles, replicating a natural viewing experience and providing a gradual transition between distances.