Effect of cap thickness on corneal biomechanical stability following smile for myopia

Abstract

Background: SMILE is a minimally invasive flapless refractive surgery with superior preservation of stromal collagen architecture. Although cap thickness is standardized between 110-120 µm, its biomechanical impact remains incompletely reported. Aim: To evaluate the effect of SMILE cap thickness variation (100 µm vs 120 µm) on corneal biomechanical stability parameters. Methods: Prospective comparative clinical study including 60 myopic eyes (30 per group). All eyes underwent SMILE using VisuMax femtosecond laser (500 kHz). Corneal biomechanics were assessed preoperatively and 6 months postoperatively using CorVis ST parameters: deformation amplitude (DA) ratio, stiffness parameter at first applanation (SP-A1), and CorVis Biomechanical Index (CBI). Inter-group and intra-group changes were statistically analysed (p