Effect of astigmatism on visual acuity after multifocal versus monofocal intraocular lens implantation

Purpose: To determine whether there is a difference in how much residual astigmatism impacts uncorrected distance visual acuity (UDVA) after multifocal versus monofocal intraocular lens (IOL) implantation. Setting: Database study. Design: Retrospective data review. Methods: An online toric IOL back-calculator allows users to input preoperative toric planning information and postoperative IOL orientation and refractive results. These data are used to determine the optimal orientation of the IOL to minimize residual refractive astigmatism. Aggregate data were extracted from this calculator to investigate factors associated with UDVA and relative magnitudes of residual astigmatic refractive error up to 2.5 diopters (D) after implantation of toric IOLs. Results: Of 1919 pertinent records (455 multifocal toric IOLs and 1464 monofocal toric IOLs), a statistically significant difference by refractive cylinder category (P < .01) and a statistically significant difference by IOL type (P = .042) were noted. This difference was mostly driven by patients with residual refractive astigmatism of 1.5 D. The mean change in UDVA was 0.16 logarithm of the minimum angle of resolution per 1.0 D of astigmatism. Evaluating a more homogenous dataset with the same monofocal and multifocal IOL design, there was a statistically significant effect of refractive cylinder (P < .01) but no significant effect of IOL type (monofocal or multifocal, P = .45). The differences in UDVA at different refractive cylinder values was not statistically significantly different by orientation of the current astigmatism (P = .28). Conclusion: Residual astigmatism after toric IOL implantation impacts visual acuity similarly in patients who had multifocal and monofocal toric IOL implantation. (C) 2018 ASCRS and ESCRS