Optimal incision sites to obtain an astigmatism-free cornea after cataract surgery with a 3.2 mm sutureless incision

Abstract

Purpose: To determine the optimal incision to eliminate astigmatism after cataract extraction. Setting: Hara Eye Hospital, Utsunomiya, Japan. Methods: Patients having cataract extraction through a 3.2 mm corneal limbal incision without limbal sutures were divided into 2 groups. Group 1 comprised 98 eyes of 80 patients without preoperative astigmatism and Group 2, 72 eyes of 62 patients with no astigmatism postoperatively. In Group 1, the incisions that caused postoperative corneal changes were retrospectively evaluated. In Group 2, the types of incisions that induced an astigmatism-free cornea postoperatively were retrospectively studied. Patients were examined preoperatively and 6 months postoperatively. Results: In Group 1, 23 of 40 eyes (57.5%) with an incision between 9 and 12 o’clock (BENT incision) and 10 of 58 eyes (17.2%) with an incision at 12 o’clock remained astigmatism free postoperatively ( P < .0001). One eye (2.5%) with a BENT incision and 17 (29.3%) with a 12 o’clock incision had astigmatism greater than 1.0 diopter (D) postoperatively ( P < .001). In Group 2, 72 eyes had less than 1.2 D of preoperative astigmatism. No eye with more than 1.2 D of astigmatism was astigmatism free postoperatively, even when the incision was made at the steepest meridian. Conclusions: The results indicate that to reduce astigmatism in eyes with preoperative astigmatism of 0.5 D or more, a limbal 3.2 mm BENT incision should be placed at 10:30 o’clock. To prevent astigmatism postoperatively, the incision should be placed at the steepest meridian in eyes with preoperative astigmatism greater than 0.5 D; for preoperative astigmatism greater than 1.2 D, a 3.2 mm incision at the corneal limbus is insufficient and a wider incision or an additional incision is required.