Vector analysis of astigmatic changes after small-incision lenticule extraction and wavefront-guided laser in situ keratomileusis

PURPOSE: To evaluate and compare the efficacy of the astigmatic correction after wavefront-guided laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) and in myopic eyes. DESIGN: Prospective case series. SETTING: Horus Vision Correction Center and Ellite Vision Correction Center, Alexandria, Egypt. METHODS: Myopic eyes with astigmatism up to 4.00 diopters (D) had wavefront-guided LASIK or small-incision lenticule extraction. Visual and refractive changes were evaluated during a 6-month follow-up. The astigmatic changes were evaluated using the Alpins method. RESULT: The study evaluated 107 eyes (55 patients), 52 eyes having wavefront-guided LASIK and 55 eyes, small-incision lenticule extraction. No statistically significant differences were found in the 6-month postoperative sphere between the 2 groups (P = .652). The postoperative manifest cylinder and spherical equivalent were significantly lower in the wavefront-guided LASIK group (P < .001). The 6-month postoperative cylinder was 0.50 D or less in all eyes in the wavefront-guided LASIK groups and in 79.8% in the small-incision lenticule extraction group (P < .001). Vector analysis showed a significantly higher difference vector (P < .001) and angle of error (P = .021) and a significantly lower correction index (P = .001) in the small-incision lenticule extraction group. The mean magnitude of error was -0.07 ± 0.20 (SD) and -0.20 ± 0.35 in the wavefront-guided LASIK group and small-incision lenticule extraction group, respectively (P = .012). CONCLUSION: Wavefront-guided LASIK and small-incision lenticule extraction were safe and effective for the correction of myopic astigmatism, although there was a trend toward undercorrection with small-incision lenticule extraction.