Outcomes of One Dioptre Toric IOL Correction in Low Corneal Astigmatism: A Comparison with Non-toric IOLs

Abstract

Toric intraocular lenses (IOLs) effectively correct astigmatism, but their benefit at low levels of corneal astigmatism remains uncertain. We compared visual and refractive outcomes between non-toric and toric IOLs in patients with low corneal astigmatism. This was a real-world comparative cohort study. We analysed 804 eyes undergoing cataract surgery for which the Barrett Toric Calculator recommended an IOL with 1 dioptre (D) of toricity. Postoperative uncorrected distance visual acuity (UDVA), refractive astigmatism and corrected distance visual acuity (CDVA) were compared between non-toric and toric IOL groups, with pre-specified subgroup analyses by astigmatism magnitude and axis. Baseline corneal astigmatism was lower in the non-toric group than in the toric group (median 0.4 versus 0.7 D; P < 0.001), reflecting surgeon selection within the Barrett-recommended 1 D toric population. Postoperative refractive astigmatism was lower in the toric group (mean 0.31 versus 0.36 D; P = 0.022), a difference smaller than the 0.25 D increment in which subjective refraction was recorded, but UDVA was comparable overall (median 79 versus 78 letters; P = 0.122) as was CDVA (median 85 versus 85 letters; P = 0.235). In the with-the-rule (WTR) astigmatism subgroup, UDVA was better with non-toric IOLs (median 80 versus 77 letters; P = 0.002); against-the-rule and oblique subgroups showed no UDVA differences. In eyes with low corneal astigmatism, 1 D toric IOLs reduced postoperative refractive astigmatism, particularly in eyes with against-the-rule (ATR) astigmatism and at higher levels of baseline corneal astigmatism, but did not improve uncorrected or corrected visual acuity overall. In eyes with WTR astigmatism, non-toric IOLs achieved better uncorrected vision. These findings suggest a statistically significant refractive benefit of low-power toric IOLs that is most evident in ATR eyes, while the functional visual benefit in this population remains uncertain and axis-dependent.