Phacoemulsification With 3.0 and 2.0 mm Opposite Clear Corneal Incisions for Correction of Corneal Astigmatism.

Purpose: To compare the effect of 3.0 and 2.0 mm opposite clear corneal incisions (OCCIs) in phacoemulsification on reduction of preexisting corneal astigmatism, and their impact on corneal aberrations. Methods: This study is a prospective randomized controlled study that included 140 patients with age-related cataract and regular corneal astigmatism >= 0.75 diopter (D). Phacoemulsification was performed using on-meridian 3.0 or 2.0 mm corneal incision with or without an OCCI. Cases were divided into 4 groups: 3.0 mm OCCIs, 3.0 mm single clear corneal incision (3.0 mm SCCI), 2.0 mm OCCIs, and 2.0 mm SCCI. Keratometry and topography were performed at 3 months postoperatively. The variations in corneal astigmatism and aberrations were recorded. Surgically induced astigmatism was calculated using vector analysis. Results: The corneal astigmatism reduction was 0.61 +/- 0.38 D in the 3.0 mm OCCIs group, significantly higher than the other groups (P <= 0.004); and 0.29 +/- 0.29 D in the 2.0 mm OCCIs group. The mean surgically induced astigmatism was 1.07 +/- 0.51 D in the 3.0 mm OCCIs group, higher than 0.61 +/- 0.35 D in the 2.0 mm OCCIs group (P = 0.001). The root mean square values of corneal trefoil, spherical aberration, and total higher order aberrations increased at 3 months postoperatively, but there were no significant differences between OCCI and SCCI groups. Conclusions: On-meridian 3.0 mm OCCIs are effective for correcting mild-to-moderate corneal astigmatism during cataract surgery, exerting no additional impact on corneal aberration compared with SCCI.