Complex sentence: There are three main varieties of expanders, which have all been derived from Fresnel prisms: the Gottlieb Visual Field Awareness System, the Chadwick hemianopsia lens, and the EP horizontal lens.
Split into simpler sentences: There are three main varieties of expanders, which have all been derived from Fresnel prisms. These include the Gottlieb Visual Field Awareness System, the Chadwick hemianopsia Lens, and the EP Horizontal Lens.