Prescriptions alternate throughout the lenses and the eye learns to compensate by using the right part of the lens when needed. The most popular type of multifocal, they are nearly always soft lenses, and are available in two designs:
Concentric ring designs – with alternating rings of distance and near powers.
Aspheric designs – progressive style, with many powers blended across the lens surface. Some aspheric lenses have the distance power in the center of the lens; others have the near power in the center.
Alternating vision (or translating) lenses:
Designed more like bifocals, the top part of the lens has the distance power for when you look straight ahead, and the bottom part of the lens contains the near power. When you look down, your lower lid holds the lens in place while your pupil moves (translates) into the near zone of the lens for reading. Commonly, these are manufactured as rigid gas permeable (GP) lenses, which are smaller.
Monovision Technique:
One eye wears a contact lens for distance-vision correction and the other eye wears a near-vision or multifocal lens. The visual system learns to automatically use the appropriate eye to focus at the right distance.
