Study of changes in pre-existing against-the-rule astigmatism after temporal manual small-incision cataract surgery using frown, straight, and smile incisions.

Abstract

To assess the change in the amount of astigmatism caused by frown, straight, and smile incision in patients with pre-existing against-the-rule (ATR) astigmatism of more than and equal to 1 diopter. This is a prospective, comparative study conducted over 18 months on 60 patients. Twenty patients were allocated to each incision using simple random sampling. Demographic details, best-corrected visual acuity (BCVA), intraocular pressure (IOP), anterior and posterior segment evaluation, and A-scan were done. An average of three measurements of K horizontal (Khavg), K vertical (Kvavg), and difference between the two (Khavg - Kvavg) were taken using manual keratometry. All surgeries were performed by a single surgeon. All the data analyses were performed by using IBM Statistical Package for the Social Sciences (SPSS) version 20 software. Frequency distribution and cross tabulation were performed to prepare the tables. In frown incision, Khavg - Kvavg was significantly decreased on day 45 from the preoperative value (P < 0.001), followed by straight incision (P < 0.001), and smile incision (P < 0.001). Maximum decrease was observed in frown incision (49.15%) followed by straight (37.75%) and smile (28.57%) incisions. Our results are consistent with reduction of pre-existing ATR astigmatism with temporal incisions, and frown incision seems to be the best approach.