Extended depth of focus intraocular lens: Chromatic performance

We describe a first-and-second-diffractive-order intraocular lens ((1^st,2^nd)DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0^th,1^st)DIOL) to (1^st,2^nd)DIOL of low addition. Compensation of LCA is experimentally assessed in optical bench through the through-focus energy efficiency of three Tecnis IOLs with red, green and blue illuminations: ZA9003 (monofocal), ZKB00 (bifocal (0^th,1^st)DIOL with + 2.75 D add) and Symfony ZXR00. We prove Tecnis Symfony ZXR00 IOL can be considered an example of (1^st,2^nd)DIOL design of low addition, with LCA compensation in both the distance and intermediate foci, whereas the bifocal (0^th,1^st)DIOL does not compensate in the distance focus. However, the energy efficiency of (1^st,2^nd)DIOL for wavelengths other than the design wavelength is markedly more asymmetric.