AIM: To investigate the changes of corneal epithelial thickness following small incision lenticule extraction(SMILE), and its relationship with the ablation depth, spherical equivalent and optical zone.

METHODS: Sixty-one myopic patients with or without astigmatism who underwent SMILE in our hospital from August 2017 to November 2017 were selected. RTvue-OCT was performed before surgery, 1wk, 1mo and 6mo after surgery, respectively, and the corneal epithelial thickness of patients were measured. The changes of corneal epithelial thickness following small incision lenticule extraction(SMILE), and its relationship with the ablation depth, spherical equivalent and optical zone were studied.

RESULTS: There was no statistically significant difference in the thickness of corneal epithelium among the three regions(central corneal region, para-central corneal region and peripheral region)before surgery(P>0.05). Compared with the baseline values before surgery, the thickness of corneal epithelium in the three areas was significantly thickened 1wk, 1mo and 6mo after surgery(P<0.05). The changes of corneal epithelium thickness in the three areas showed a significant decreasing trend from the central corneal area to the peripheral area, that is, the corneal epithelium thickened in the shape of a convex lens. The values of corneal epithelium thickness in the central and para-central areas were positively correlated with the equivalent sphericity and ablation depth, but there was no significant correlation with the optical zone.

CONCLUSION: The corneal epithelial thickness increases after SMILE in different regions, and the thickening value was positively correlated with the spherical equivalent, ablation depth.