Visualization of Ray Propagation Through Extended Depth-of-Focus Intraocular Lenses

Extended depth-of-focus (EDoF) presbyopia-correcting intraocular lens (IOL) models differ in their optical design and performance. In the laboratory, we compared the ray propagation and light intensity profiles of four IOLs: the non-diffractive AcrySof IQ Vivity (Alcon Inc., Fort Worth, TX, USA) and two diffractive models, Symfony ZXR00 (Johnson & Johnson Vision, Jacksonville, FL, USA) and AT Lara 829 MP (Carl Zeiss Meditec, Berlin, Germany). A fourth lens, the monofocal AcrySof IQ SN60WF (Alcon Inc.) acted as the control. We projected a 520 nm laser light through each submerged lens in a bath of fluorescein solution. A camera mounted on a microscope captured the light that emerged from the IOL. We recorded the IOLs' point spread function (PSF) to determine the presence of unwanted visual effects. The ray propagation visualization and light intensity profile of the monofocal control showed one distinct focus, while the AcrySof IQ Vivity demonstrated an extended focus area. We observed two distinct foci with each diffractive IOL. We found a lower level of light spread beyond the PSF center for the AcrySof IQ Vivity compared to the diffractive IOLs. In conclusion, we could confirm the extended range of focus for all the EDoF IOL models. However, the non-diffractive AcrySof IQ Vivity appears to have a smoother transition from a far to an intermediate range. We discuss whether, in clinical use, the higher level of spurious light we found in the diffractive designs may translate into increased dysphotopsia.