[Effect of incision form and tunnel length on induced astigmatism with the no-stitch technique]

The frown incision with horizontal suture can induce minimal astigmatism. This method is also currently used with the no-stitch technique. We assess whether it is better than other incisions. Two prospective studies were conducted, altogether including 95 operations in 95 patients. Entry criterion was preoperative astigmatism < 0.75 D. Astigmatism was assessed at 1 week and 4 weeks postoperatively. First study: induced astigmatism with three incision types--frown (A), horizontal arc (B) and limbus-based (C). Second study: induced astigmatism with trapezoid incision--2-mm or 4-mm tunnel. The induced astigmatism did not differ significantly in the three incision types: A 0.82, B 0.67, C 0.8 D. Using the trapezoid incision with 2-mm and 4-mm tunnel the induced astigmatism was 0.3 and 0.38 D, respectively. This difference was also not significant. Thus, neither incision type nor preparation of a longer tunnel has any influence on postoperative induced astigmatism.