ABSTRACT
Objective To evaluate the changes in epithelial thickness profile and its relationship with diopter following small incision lenticule extraction (SMILE) for moderate and high myopia.Methods Together 46 myopia or myopic astigmatism (92 eyes) who underwent SMILE were included under the informed consent from January 2016 to March 2017 and were decided into 2 groups according to the diopter:moderate myopia group (58 eyes)and high myopia group (34 eyes).Epithelial thickness profile was measured using spectral-domain optical coherence tomography at different corneal zones (0-2 mm,＞ 2-5 mm and ＞ 5-6 mm cornea) preoperatively before surgery and 1 month and 6 months after surgery for observing the changes in epithelial thickness and its correction with diopter.Results The mean epithelial thickness in the central zone was (55.68 ± 3.61) μm before surgery,and,6 months after surgery,it was thickened by (3.85-±3.99),(3.46 ±3.29) and (2.85 ±3.18) μm in the 0-2 mm,＞2-5 mum and ＞5-6 mm cornea respectively,and the difference was statistically significant among the three zones (P ＜ 0.01).After surgery for 6 months,the epithelial thickness in the high myopia group was thickened more obviously compared with the moderate myopia group (t =1.440,P =-0.047).And no correlation was found between changes in the epithelial thickness at 0-2 mm cornea and diopter after surgery(moderate myopia group:r =0.219,P=0.633;high myopia group:r =0.197,P =0.585).Conclusion Significant epithelial thickening was observed after SMILE,presenting the thickened epithelium.The higher the diopter was,the more thickened the epithelium was.The epithelial changes does not appear to affect the diopter after SMILE.