Tomographic analysis of anterior and posterior surgically induced astigmatism after 2.2 mm temporal clear corneal incisions in femtosecond laser–assisted cataract surgery

Purpose To evaluate surgically induced astigmatism (SIA) of temporal clear corneal incisions (CCIs) on anterior and posterior corneal curvature after femtosecond laser–assisted cataract surgery (FLACS) using Scheimpflug tomographic measurements. Setting Department of Ophthalmology, Goethe University, Frankfurt am Main, Germany. Design Prospective interventional case series. Methods This study enrolled patients who underwent FLACS from June 2013 to July 2014. All eyes were measured with a Pentacam HR preoperatively and at 1 month and 3 months postoperatively, had preoperative total corneal refractive power (TCRP) astigmatism (CATCRP) of 0.50 diopters (D) or less, and received a temporal 2.2 mm incision at 0 degrees and 180 degrees. Vector analysis, using the Holladay-Cravy-Koch formula and the Alpins method, determined astigmatic changes in anterior corneal astigmatism (CAant), posterior corneal astigmatism (CApost), and CATCRP. Student t and Wilcoxon tests were performed. A P value less than 0.05 was considered statistically significant. Results This study comprised 53 eyes of 38 patients. At 3 months postoperatively, the CAant, CApost, and CATCRP were significantly higher compared with the preoperative values (P = .015, P = .007, P = .008, respectively); however, CApost and CATCRP were significantly lower compared with the limit of 0.50 D (P < .001, P = .01, respectively), whereas CAant was not (P = .11). The mean SIA of CAant, CApost, and CATCRP was 0.25 D ± 0.15 (SD), 0.16 ± 0.11 D, and 0.28 ± 0.17 D, respectively. The angle of error was high (−1.98 ± 52.95 degrees, 1.64 ± 51.27 degrees, and −1.72 ± 48.79 degrees, respectively). Conclusion Femtosecond laser temporal CCIs induce minimal astigmatism in CAant, CApost, and CATCRP, but can be evaluated statistically as astigmatically neutral.