SMILE and FS-LASIK produced distinct changes in anterior corneal shape evident in different postoperative corneal curvatures and power measurements between the two groups. Postoperative HOAs were much lower after SMILE as compared to FS-LASIK.

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Ray tracing calculations based on Scheimpflug imaging accurately assessed the change in manifest refraction due to corneal laser surgery.

Almost 25% of the variation after small-incision lenticule extraction for myopic astigmatism might be explained by the size of the attempted cylinder correction and ATR/WTR astigmatism. Incorporating these parameters in preoperative planning might produce more consistent results in high cylinder corrections.

Purpose: To investigate whether postoperative-induced refractive astigmatism after small-incision lenticule extraction (SMILE) could be predicted by preoperative objective astigmatism measured with autorefraction, keratometry, and Scheimpflug tomography. Setting: University eye clinic. Design: Retrospective case series. Methods: Only eyes without preoperative subjective astigmatism treated with SMILE for myopia were included. Postoperative subjective astigmatism was compared with preoperative objective astigmatism. Examinations were performed before SMILE and 3 months postoperatively and included subjective refraction, keratometry, autorefraction, and Scheimpflug tomographer measurements. Astigmatism was analyzed using double-angle plots and multivariate statistics. Results: A total of 358 eyes of 358 patients were included. The mean preoperative sphere was −7.33 diopter (D) ± 1.46 (SD). The postoperative spherical equivalent was −0.30 ± 0.49 D. Postoperatively, 79.6% and 98.9% of patients had a subjective cylinder ≤0.50 D and ≤1.00 D, respectively. Preoperative objective astigmatism measured with keratometry, autorefraction, and Scheimpflug tomography was significantly different (P < .05) from postoperative subjective refraction when all patients were analyzed; for patients with postoperative refractive astigmatism ≥0.50 D, preoperative astigmatism with keratometry and Scheimpflug tomography was not significantly different from postoperative refractive astigmatism. Preoperative objective astigmatism ≥0.50 D increased the risk ratio of postoperative subjective astigmatism ≥0.50 D by 2.2 (P < .001). Conclusions: Preoperative objective astigmatism could not be directly interchanged with postoperative subjective astigmatism, but the presence of preoperative astigmatism ≥0.50 D doubled the risk of inducing a postoperative subjective astigmatism ≥0.50 D. Extra care when performing subjective refraction should be taken in the presence of high objective astigmatism.