Comparison of modal and zonal wavefront measurements of refractive extended depth of focus intraocular lenses

Extended depth-of-focus (EDoF) intraocular lenses (IOLs) are typically evaluated using commercially available aberrometers. Given the intricate optical design of these IOLs, employing an appropriate wavefront reconstruction method with a sufficient sampling resolution of the aberrometer is crucial. A high-resolution Shack-Hartmann wavefront sensor was developed by magnifying the pupil aperture by a factor of five onto a lenslet array (pitch: 133 mu m) and utilizing a full-frame CMOS sensor (24 by 36 mm), resulting in a 26.6 mu m sampling resolution. Zonal wavefront reconstruction was used and compared with Zernike-based modal wavefront reconstruction to retain detailed local slope irregularities. Four refractive EDoF IOLs with a power of 20D were examined, and the wavefront difference between the zonal and modal methods, expressed as the root mean squared error (RMSE), remained significant for two of the IOLs up to the 16th-order Zernike spherical aberrations (SAs). Conversely, a negligibly small RMSE was observed for the other two IOLs, as long as the Zernike SAs were higher than the 6th order. The raytracing simulation results from the zonal wavefronts exhibited a stronger correlation with the results of recent optical bench studies than those from the modal wavefronts. The study suggests that certain recent refractive EDoF IOLs possess a complex optical profile that cannot be adequately characterized by limited orders of SAs.