Author: Matt Jaskulski, University of Murcia
The modern MPlus intra-ocular lenses (IOL's) (Oculentis®, http://www.oculentis.com/lentis-mplus-x.html) offer to the wearers an expanded depth of focus thanks to their multi focal design. However some (about 6% according to the manufacturer) users wearing them express discontent regarding their vision quality. Within the AGEYE network we developed a novel computational method based on simulations of retinal images that aims to answer the question "why".
Our custom simulator program allows the computation of polychromatic smulated retinal images from experimental aberrometric data. The software uses a novel implementation of Fourier and geometrical optics and the Indiana Eye Model to calculate polychromatic PSF's (pointspread functions) and simulated retinal images. It can perform through-focus simulations and image quality estimation. It has been used to perform analyses of 5 presbyopic eyes with implanted IOL's (3.0D of addition). The optical design of this family of lenses, where the power varies continuously along the surface, allows us to perform aberrometric measurements using commonly available aberrometers.
Our analysis confirmed that most of the subjects have two zones of distances with better image quality. The dioptric range between the two points of maximum IQ was 2.2 ± 0.3D. In the "content" group of eyes that meant that a decent visual acuity (VA) of at least 0.4 - 0.5 logMAR was achieved within this range of distances. The IQ in the "discontent" was 2 to 3 times lower and the simulated images either exhibited double "ghost" images or no bifocality at all. And so the two possible causes of discontent: lack of bi-focality or double "ghost" images. We believe that in the future it will be possible to find the required change of optical aberrations that will optimize the IQ for each particular eye without the need to extract the lens from the eye.