Regular and irregular astigmatism after superior versus temporal scleral incision cataract surgery

Abstract

Objective To evaluate the effect of superior and temporal scleral incisions on regular and irregular astigmatism in small incision cataract surgery. Design Prospective, randomized, comparative clinical trial. Participants One hundred seventy-four eyes of 87 patients with bilateral cataracts scheduled to undergo routine cataract surgery. Methods One eye of each patient was randomly assigned to the superior incision group, and the contralateral eye was allocated to the temporal incision group. Phacoemulsification and intraocular lens implantation were performed through an unsutured 4.1-mm scleral incision. Patients were examined 1 day and 1, 3, and 6 months after surgery. Main outcome measures Surgically-induced regular astigmatism calculated with vector analysis method, irregular astigmatism obtained by Fourier analysis of videokeratography data, and uncorrected and corrected visual acuity. Results Postoperatively, the superior incision group showed slight against-the-rule astigmatic changes, whereas slight with-the-rule astigmatism was seen in the temporal incision group. The amount of against-the-wound astigmatism and absolute value of length of the induced vector did not differ significantly between groups ( P > 0.05, paired t test). In both groups, irregular astigmatism 1 day after surgery was significantly greater than the preoperative levels ( P < 0.001), but not thereafter. No significant intergroup difference was observed in the amount of irregular astigmatism at any postoperative visits ( P > 0.05). There was no significant difference in uncorrected and corrected visual acuity between groups postoperatively ( P > 0.05, chi-square test). Conclusions In small scleral incision cataract surgery, superior and temporal approaches are comparable in terms of visual rehabilitation and induction of regular and irregular astigmatism.