Effect of Residual Astigmatism on Visual Acuity Following Bifocal, Trifocal, and Extended Depth-of-Focus Intraocular Lens Implantation: A Retrospective Cohort Study

This study aimed to evaluate the effects of residual astigmatism magnitude and axis on visual outcomes after simultaneous vision intraocular lens (SVIOL) implantation. This retrospective cohort study reviewed medical records of cataract patients who underwent implantation of bifocal, trifocal, or extended depth-of-focus (EDOF) IOLs. Patients were stratified by residual astigmatism magnitude (mild [0–0.50 D], moderate [0.75–1.00 D], high [1.25–1.50 D]) and axis (with-the-rule [WTR], against-the-rule [ATR], oblique). Uncorrected distance, intermediate, and near visual acuities (UDVA, UIVA, UNVA) and corrected distance visual acuity (CDVA) recorded at the 1-month postoperative visit were extracted for analysis. A total of 879 eyes from 879 patients were analyzed (bifocal: 497 [56.5%]; trifocal: 166 [18.9%]; EDOF: 216 [24.6%]). In the bifocal group, UDVA, UIVA, and UNVA worsened with increasing astigmatism (all P < 0.05), whereas CDVA declined only in the high-astigmatism subgroup ( P < 0.05). In the trifocal group, mild astigmatism yielded better UDVA, UIVA, and UNVA than moderate or high astigmatism (all P < 0.05) and better CDVA than the high-astigmatism subgroup ( P < 0.05). In the EDOF group, mild astigmatism outperformed moderate and high astigmatism in UDVA and UIVA (both P < 0.05) and high astigmatism in UNVA and CDVA (both P < 0.05). Trifocal IOLs with mild or moderate astigmatism achieved better intermediate and near vision than other IOL types, whereas EDOF IOLs outperformed bifocal IOLs in the high-astigmatism subgroup (all P < 0.05). Astigmatic axis did not independently predict visual acuity in stratified multiple linear regression (all P > 0.05). Mild-to-moderate astigmatism primarily impairs intermediate and near vision, with trifocal IOLs exhibiting greater tolerance, whereas high astigmatism degrades vision at all distances, a setting in which EDOF IOLs perform better. Astigmatic axis appears to exert little influence.