Multifocal intraocular lens providing optimized through-focus performance.

A widespread type of multifocal intraocular lens (MIOL) is based on expanding the depth of focus with specific amounts of spherical aberration. However, knowing the optimal wavefront aberration for multifocality does not directly provide a MIOL geometry. To overcome this issue, we present a new strategy to design MIOLs. The method optimizes directly the IOL surface geometries (aspheres with aspherical coefficients up to tenth order) using a multisurface pseudophakic eye model and a multiconfiguration approach, where the merit function jointly considers the optical quality at different object plane locations. An example of MIOL [22 diopters (D) far distance correction] was designed. For this design, the ocular modulator transfer function (MTF) at 50 cycles per millimeter remained above 0.47 for all object locations. The design provides high optical quality performance for far and intermediate distances and peak optical performance at near distances (MTF>0.57). Additionally, the design shows good performance against pupil changes (3-5 mm pupil diameter range). Finally, when the MIOL was tested on pseudophakic eye models with corneal spherical aberrations within a typical population range, the high multifocal performance was maintained in almost 40% of potential patients (ignoring asymmetric aberrations effects).