title: Epithelial Thickness Profile Changes Following Small Incision Refractive Lenticule Extraction (SMILE) for Myopia and Myopic Astigmatism.
abstract: OBJECTIVE
  To evaluate the epithelial thickness profile changes following small incision refractive lenticule extraction (SMILE) and study their correlation with the amount of myopia corrected.
  
  
  METHODS
  Epithelial thickness was measured in nine zones with spectral-domain anterior segment optical coherence tomography (SD-OCT) across a 6-mm diameter preoperatively and at 1 day, 2 weeks, and 3 months postoperatively. The observed changes were correlated with the degree of myopia corrected.
  
  
  RESULTS
  The study included 100 eyes from 50 eligible patients (32 females, 18 males) with a mean age of 24.4 ± 2.8 years. Thirty-eight eyes underwent SMILE for low (spherical equivalent [SE] < -4.00 diopters [D]), 44 eyes for moderate (SE -4.00 to -6.00 D), and 18 eyes for high (SE > -6.00 to -10.00 D) myopia with 6.71 ± 1.65, 6.82 ± 0.21, and 6.44 ± 0.2 mm optical zones, respectively. At 3 months, a statistically significant epithelial thickness increase was observed in the central zone (6.83% for low, 9.26% for moderate, and 12.7% for high myopia, P < .05 for all groups) and superior zone (3.98% for low, 7.82% for moderate, and 9.87% for high myopia) across all three groups, which correlated positively with the degree of myopia corrected (r(2) = 0.723 for central zone, r(2) = 0.585 for superior zone, P < .001 for both zones). None of the other zones showed any statistically significant changes at 3 months. Four eyes of two patients with high myopia (SE > -8.00 D) had regression due to significant epithelial thickening.
  
  
  CONCLUSIONS
  Preliminary results suggest that epithelial thickness profile changes after SMILE may have an impact on the refractive outcome in the long-term postoperative period, especially in higher degrees of myopia. [J Refract Surg. 2016;32(7):473-478.].
authors.forename: Sri
authors.initials: S
authors.lastname: Ganesh
authors.forename: Sheetal
authors.initials: S
authors.lastname: Brar
authors.forename: Kirti J
authors.initials: KJ
authors.lastname: Relekar
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003319:Corneal Stroma / Q000601:surgery*; D048988:Corneal Surgery, Laser; D019781:Corneal Topography; D004847:Epithelial Cells / Q000473:pathology; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D041623:Tomography, Optical Coherence; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult