Effects of preoperative corneal astigmatism orientation on results with a low-cylinder-power toric intraocular lens

PURPOSE: To evaluate refractive results with a low-cylinder-power toric intraocular lens (IOL) and the effect of preoperative corneal astigmatism orientation on results. SETTING: Private practice, Jackson, Michigan, USA. DESIGN: Comparative case series. METHODS: This retrospective review of clinical records comprised patients with 0.75 to 1.38 diopters (D) of preoperative corneal astigmatism who had uneventful cataract surgery and AcrySof T3 toric or AcrySof 110 spherical monofocal IOL implantation. Surgically induced astigmatism (SIA) was calculated for eyes with postoperative keratometry results. Postoperative refractive astigmatism between groups and subgroups was compared based on the orientation of preoperative corneal astigmatism. RESULTS: Of the eyes, 185 had a toric IOL and 138 had a spherical IOL. The mean preoperative corneal astigmatism was 1.06 D, with no significant difference between IOL groups or by axis of astigmatism. The mean SIA was 0.25 D, with no significant difference between IOL groups. The mean postoperative refractive astigmatism was statistically significantly lower in the toric IOL group than in the spherical IOL group (0.31 D versus 1.06 D; P<.001). The axis of preoperative corneal astigmatism was not a significant factor in the toric IOL group. In the spherical IOL group, the residual astigmatism was slightly higher for with-the-rule than for against-the-rule astigmatism (1.07 D versus 0.70 D; P<.001). CONCLUSIONS: The mean refractive astigmatism after cataract surgery in patients with 0.75 D to 1.38 D of corneal astigmatism was significantly lower when a toric IOL was implanted. Postoperative refractive astigmatism with the toric IOL was independent of preoperative corneal astigmatism axis orientation.