Changes in Corneal Biomechanical Properties After Small-Incision Lenticule Extraction and Photorefractive Keratectomy, Using a Noncontact Tonometer.

Abstract

The aim of this study was to evaluate and compare early corneal biomechanical changes after small-incision lenticule extraction (SMILE) and photorefractive keratectomy (PRK). The study comprised 74 patients eligible for refractive surgery, equally allocated to PRK (37 patients) and SMILE (37 patients). Corneal biomechanical properties were recorded and compared between the 2 groups at preoperatively and 3 months after surgery using a dynamic ultra-high-speed Scheimpflug camera equipped with a noncontact tonometer. Both procedures significantly affected corneal biomechanical properties at 3 months after surgery. Patients in the PRK group showed significantly better results for deformation amplitude ratio (DA ratio) ( P = 0.03), maximum inverse radius (InvRadMax) ( P = 0.02), and A2 time ( P = 0.03). The mean changes in DA ratio, HC radius, InvRadMax, and Ambrosio relational thickness were significantly higher in the SMILE group in comparison with those of the PRK group (all, P < 0.05). In both groups, change in CCT was significantly correlated with changes in DA ratio and InvRadMax ( P < 0.05). Both SMILE and PRK refractive surgeries significantly altered corneal biomechanical properties but the changes were more prominent after SMILE.