Changes in the corneal epithelium after myopia correction by SMILE and FemtoLASIC methods

Purpose. To conduct a comparative analysis of the thickness and topographic distribution of the corneal epithelium at various stages of the postoperative period in patients with moderate myopia after refractive surgery performed by SMILE and FemtoLASIK methods. Material and methods. A total amount of 152 patients with moderate myopia were examined. Depending on the type of refractive surgery, two comparison groups were formed: group 1 – 68 patients with moderate myopia operated by the SMILE method; group 2 – 84 patients with moderate myopia operated by FemtoLASIK. Examinations were performed before surgery and in the postoperative period 1, 5 days, 3, 6, 12 months after surgery. Results. The total epithelial thickness index after SMILE surgery changed in general by the year from 52.41±8.45 to 55.21±9.01 (p>0.05). After FemtoLASIK surgery, there was a gradual increase in epithelial thickness from the first day to a year, without a clear tendency to stabilization, from 51.77±10.09 to 57.30±9.5 (p<0.001). The difference between the comparison groups was statistically significant (p<0.05). The topographic difference of the maximum indices of epithelial hypertrophy in different types of surgery was also noted. Conclusion.SMILE technology is accompanied by asymmetric hypertrophy of the epithelium in the temporal and lower temporal zones which is completed by the 3rd month of the postoperative period. Unlike FemtoLASIK is characterized by almost one and a half times excess of the thickness of the corneal epithelium and the absence of significant stabilization even 12 months after surgery, which indicates ongoing corneal remodeling and incomplete process of postoperative healing. Key words: myopia, SMILE, FemtoLASIK, epithelial hypertrophy, femtosecond laser