Corneal Changes In Eyes After Laser Refractive Surgery

The aim of this study is to determine whether there is an increase in corneal epithelial thickness after laser myopia correction and whether there is a shift in posterior or anterior corneal surface elevation. We correlate these values with the amount of ablation and compare them between the SMILE and Femto-LASIK procedures. 

Lexum eye clinic, Brno, Czech Republic, Optegra group 

Masaryk University, Faculty of Medicine, ​Department of Optometry and Orthoptics​, Brno, Czech Republic

The retrospective study was conducted from June 2024 to February 2025 at the Lexum Eye Clinic in Brno. The study involved 50 eyes. An epithelial map divided into 25 segments is created on the MS-39 device (ASOCT; CSO) and compared preoperatively and postoperatively. Postoperative results are recorded one month and three months after the procedure. Posterior corneal surface elevation is recorded preoperatively and one month postoperatively using a Scheimpflug system (Pentacam; Oculus, Inc). These instruments also analysed the ratio of refraction of the posterior to anterior corneal surface, relative pachymetry and keratometry. 

The mean difference between preoperative and postoperative epithelial thickness values in each segment is -1.1 (central), -2.8 (2-0), -0.8 (2-90), -2.5 (2-180), -1.7 (2-270), -3.1 (3-23), -2.3 (3-68), -3.1 (3-113), -3, 8 (3-158), -2,7 (3-203), -2,9 (3-248), -3,6 (3-293), -3,1 (3-338), -3,0 (4-0), -3 (4-30), +1,0 (4-60), +0,3 (4-90), -3.5 (4-120), -3.7 (4-150), -2.7 (4-180), -1.7 (4-210), -1.1 (4-240), -1.1 (4-270), -1.9 (4-300), and -3.4 µm (4-330). The results show that as early as one month after laser refractive surgery, there was an increase in epithelial thickness (p < 0.05). At one month, there was also an increase in elevation of the anterior and posterior corneal surfaces (p < 0.01 and p = 0.02, respectively). 

The results of the study suggest that there are statistically significant changes after laser vision correction procedures, namely an increase in corneal epithelial thickness and an increase in elevation of the anterior and posterior corneal surfaces. Keratometry of the posterior corneal surface did not change statistically significantly.