Astigmatism correction and corneal aberrations variability between two locations of cap side-cut after small incision lenticule extraction: a randomized study

Purpose: To investigate astigmatism correction and the effect on corneal aberrations between two locations of the cap side-cut (CSC) after small incision lenticule extraction(SMILE) surgery. Methods: In this randomized, prospective research, 91 eyes of 49 patients were investigated after SMILE. The eyes were randomized into two groups with different CSC locations. The location was set at 120° for group 1 and 90° for group 2. Uncorrected distant vision acuity (UDVA) and corrected distant vision acuity measurements, manifest refraction, and imaging were performed before and after surgery. Results: At the 3-month follow-up, all eyes in both groups had a postoperative UDVA ≥ 20/20. There was no significantly difference in the refraction data nor in the safety and efficacy indices between the two groups (P=0.343 and P=0.738, separately) . The effects on corneal astigmatism, corneal root mean square high-order aberration, corneal spherical aberration, and corneal coma aberration at 0º and 90º showed no difference between the two groups. Conclusions: Astigmatic correction was not influenced by two locations of the CSC in SMILE surgery. No significant difference was found in visual and corneal optical quality results with two different CSCs in SMILE surgery.