Comparison of corneal biomechanical changes after LASIK and F-SMILE with CorVis ST

Abstract

Purpose: To evaluate changes in corneal biomechanics after LASIK and F-SMILE. Setting: Elite Eye Center, Tanta, Egypt. Design: Prospective, randomized, unmasked, interventional comparative case series. Patients and methods: A total of 60 eyes were equally divided into two groups; group A: received LASIK and group B: received F-SMILE. Pentacam and CorVis ST parameters were compared before and 6 months after procedures. P ⩽ 0.05 was used for significance of results. Results: bIOP decreased by 0.762 ± 1.211 mmHg in group A ( p = 0.092), and by 2.52 ± 1.389 mmHg in group B ( p < 0.001) and the difference between groups became significant ( p = 0.001). A1 increased significantly in group A only ( p = 0.036); while A2 decreased insignificantly in both groups. DAR increased significantly in both groups ( p < 0.001, p = 0.022), but the difference between groups remained insignificant ( p = 0.461). IR increased significantly in group A only ( p < 0.001) and the difference between groups became significant ( p = 0.026). ARTH decreased in both groups ( p = 0.245, p = 0.695) and the difference remained insignificant ( p = 0.928). SP-A1 decreased in group A by 8.89 ± 1.38 mmHg/mm ( p = 0.637), and by 32.6 ± 4.39 mmHg/mm in group B ( p < 0.001) and the postoperative difference between groups was significant ( p = 0.013). CBI increased significantly in group A ( p < 0.001), but insignificantly in group B ( p = 0.098) and postoperative difference between groups was highly significant ( p < 0.001). A significant correlation was found between change in CCT and corresponding changes in DAR, IR, and ARTH after surgery in both groups. Conclusion: The significant differences between groups postoperatively as regards bIOP ( p = 0.001), IR ( p = 0.026), SP-A1 ( p = 0.013), and CBI ( p < 0.001) indicate stiffer corneas after F-SMILE and suggest less influence on corneal biomechanics than LASIK.