Subjective and objective depth of field measures in pseudophakic eyes: comparison between extended depth of focus, trifocal and bifocal intraocular lenses

Abstract

Purpose: To evaluate different intraocular lens (IOL) designs and to determine whether extended depth of focus (EDOF) lenses provide a higher depth of field (DOF) than the rest considering both subjective and objective measurements.

Methods: A total of 100 eyes undergoing cataract surgery were divided into six groups depending on the IOL implanted: bifocal designs were Tecnis ZMB and ZLB (Abbott Laboratories, Illinois, USA), trifocal designs were Finevision (PhysIOL, Liège, Belgium) and AT LISA Tri (Carl Zeiss Meditec., Jena, Germany) and EDOF designs were Symfony (Abbott Laboratories, Illinois, USA) and MiniWell (SIFI MedTech, Catania, Italy). Subjective DOF was obtained from defocus curves for the range of vergences which provide a VA over 0.1 LogMAR and 0.2 LogMAR. Aberrometry was measured and Visual Strehl Optical Transference Function (90%) was used to quantify objectively the DOF.

Results: Symfony IOL group showed better subjective and objective DOF compared to the rest of IOL groups, with statistically significant differences (p < 0.001). Comparison between subjective and objective DOF showed that subjective measures were higher for all IOLs, being these differences statistically significant for all groups when compared with objective measures (p < 0.001).

Conclusion: Objective and subjective measures of DOF are not comparable due to differences in methodologies and criterions to define the level of degradation acceptance. Nevertheless, both objective and subjective measures demonstrate a greater DOF for EDOF designs compared to bifocal and trifocal IOLs, being the Symfony IOL the one providing higher levels of subjective and objective DOF.

Keywords: Aberrometry; Cataract surgery; Defocus curves; Depth of field; Depth of focus; Extended depth of focus IOL; Pseudophakic.