Comparison of the effects of single and opposite incision techniques on with-the-rule astigmatism in cataract surgery

PURPOSE: To compare the effects of single clear corneal incision (CCI) and opposite clear corneal incision (OCCI) techniques on corneal and total astigmatism in patients undergoing phacoemulsification cataract surgery. METHODS: This retrospective comparative study included 285 eyes of 285 patients with preoperative total astigmatism of 0.75-3.0 diopters and corneal astigmatism of 0.50-2.0 diopters. Patients were divided into two groups: OCCI (141 eyes) and CCI (144 eyes). All surgeries were performed by the same surgeon using a standardized phacoemulsification technique with 2.4-mm clear corneal incisions placed on the steep meridian. In the OCCI group, a second identical incision was created 180° opposite the primary incision. Corneal astigmatism, total astigmatism, spherical equivalent, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and intraocular pressure were evaluated preoperatively and during a minimum 12-month follow-up. RESULTS: Preoperative demographic and ocular characteristics were comparable between groups (all p > 0.05). Postoperatively, corneal astigmatism was significantly lower in the OCCI group compared with the CCI group (- 0.71 ± 0.48 D vs. -1.01 ± 0.56 D; p = 0.001). Total astigmatism was also significantly reduced in the OCCI group (- 1.19 ± 1.20 D vs. -1.51 ± 0.71 D; p = 0.004). Spherical equivalent and intraocular pressure did not differ significantly between groups. BCVA outcomes were comparable at all follow-up visits (p > 0.05). However, UCVA was significantly better in the OCCI group at 3 months (p = 0.047) and 12 months (p = 0.031). CONCLUSIONS: Opposite clear corneal incisions provide a stronger astigmatic corrective effect than single clear corneal incisions and result in superior uncorrected visual acuity at mid- and long-term follow-up. OCCI represents a simple, safe, and effective technique for correcting mild to moderate astigmatism during routine cataract surgery.