the diffractive multifocal iol provides simultaneous bifocal imaging by utilizing both diffractive and refractive optics. in both distant and near vision, there is a clear highly focused image on the retina. the second image is highly defocused, providing only faint background illumination. a small amount of the light goes to the higher orders of diffraction which are not perceptible by eyes. t...

PURPOSE To present a bi-sign aspheric intraocular lens (IOL) and make theoretical comparisons with spherical and one-sign aspheric IOLs for retinal image quality in mesopic conditions and intermediate image capability in photopic conditions. METHODS Using ray-tracing in pseudophakic eye models, retinal image quality in terms of modulation transfer function was analyzed between the bi-sign asp...