An ophthalmic lens for providing a plurality of foci has an optic including an anterior surface, a posterior surface, and an optical axis. The ophthalmic lens further includes a central phase plate, an intermediate phase plate surrounding the central phase plate, and an outer refractive region. The central...http://www.google.de/patents/US7922326?utm_source=gb-gplus-sharePatent US7922326 - Ophthalmic lens with multiple phase plates
