Chromatic aberration and polychromatic image quality with diffractive multifocal intraocular lenses

Purpose To evaluate the impact of target distance on polychromatic image quality in a virtual model eye implanted with hybrid refractive–diffractive intraocular lenses (IOLs). Setting School of Optometry, Indiana University, Bloomington, Indiana, USA. Design Experimental study. Methods A pseudophakic model eye was constructed by incorporating a phase-delay map for a diffractive optical element into a reduced eye model incorporating ocular chromatic aberration, pupil apodization, and higher-order monochromatic aberrations. The diffractive element was a monofocal IOL with a +3.2 diopter (D) diffractive power or 2 types of bifocal IOLs (nonapodized or apodized) with a +2.92 D addition (add) power. Polychromatic point-spread functions and image quality for white and monochromatic light were quantified for a series of target vergences, wavelengths, and pupil diameters using modulation transfer functions and image-quality metrics. Results Ocular longitudinal chromatic aberration was largely corrected by the monofocal design and by both bifocal designs for near targets. In the bifocal design, add power and the ratio of distance:near image quality changed significantly with wavelength and pupil size. Also, image quality for distance was better with the apodized design. Conclusions Achromatization by the diffractive IOL provided significant improvement in polychromatic retinal image quality. Along with apodization and higher-order aberrations, it can significantly affect the near–distance balance provided by a diffractive multifocal IOL. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.