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

Objective: To evaluate the effect of superior and temporal scleral incision s on regular and irregular astigmatism in small incision cataract surgery. Designs Prospective, randomized, comparative clinical trial. Participants: One hundred seventy-four eyes of 87 patients with bilateral c ataracts scheduled to undergo routine cataract surgery. Methods: One eye of each patient was randomly assigned to the superior inci sion group, and the contralateral eye was allocated to the temporal incisio n group. Phacoemulsification and intraocular lens implantation were perform ed through an unsutured 4.1-mm scleral incision. Patients were examined 1 d ay and 1, 3, and 6 months after surgery. Main Outcome Measures: Surgically-induced regular astigmatism calculated wi th vector analysis method, irregular astigmatism obtained by Fourier analys is 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 astigm atism and absolute value of length of the induced vector did not differ sig nificantly between groups (P > 0.05, paired t test). In both groups, irregu lar astigmatism 1 day after surgery was significantly greater than the preo perative levels (P < 0.001), but not thereafter. No significant intergroup difference was observed in the amount of irregular astigmatism at any posto perative visits (P > 0.05), There was no significant difference in uncorrec ted and corrected visual acuity between groups postoperatively (P > 0.05, c hi-square test). Conclusions: In small scleral incision cataract surgery, superior and tempo ral approaches are comparable in terms of visual rehabilitation and inducti on of regular and irregular astigmatism. Ophthalmology 2000;107: 2049-2053 (C) 2000 by the American Academy of Ophthalmology.