In this presentation, we review the design principles and operational features for a multi-order diffractive singlet lens that brings a multiplicity of wavelengths to a common focus with high diffraction efficiency. This multi-order diffractive lens is used as an anterior-chamber, phakic intraocular lens to provide vision correction for both myopia (nearsightedness) and hyperopia (farsightedness). Initial human trials of the lens are extremely promising.