title: Comparison of femtosecond laser small-incision lenticule extraction and laser-assisted subepithelial keratectomy to correct myopic astigmatism.
abstract: OBJECTIVE
  To compare the efficacy of correcting myopic astigmatism with femtosecond laser small-incision lenticule extraction (SMILE, Carl Zeiss Meditec AG) versus laser-assisted subepithelial keratectomy (LASEK).
  
  
  METHODS
  The study was conducted at the Ophthalmology Department, Eye and ENT Hospital, Shanghai, China.
  
  
  METHODS
  A retrospective, cross-sectional study.
  
  
  METHODS
  This study included patients who underwent small-incision lenticule extraction or LASEK for the correction of myopia and myopic astigmatism. Preoperative and 6-month postoperative astigmatism values were analyzed. The efficacies of the 2 surgeries to correct astigmatism were compared.
  
  
  RESULTS
  A total of 180 right eyes of 180 patients (small-incision lenticule extraction: n = 113, LASEK: n = 67) were included. No significant difference was found between the 2 groups in the preoperative astigmatism (small-incision lenticule extraction: 1.16 ± 0.85D, LASEK: 1.16 ± 0.83D, P > .05) or the postoperative astigmatism (small-incision lenticule extraction: 0.35 ± 0.37D; LASEK: 0.31 ± 0.42D, P > .05), determined by manifest refraction. No significant difference was found between the 2 groups in surgically induced astigmatism vector (small-incision lenticule extraction: 1.13 ± 0.83D, LASEK: 1.01 ± 0.65D, P > .05). The correction index was higher for the small-incision lenticule extraction group (1.05 ± 0.53) than for the LASEK group (0.95 ± 0.21, P = .045). The postoperative astigmatism was significantly higher for the small-incision lenticule extraction group when the preoperative astigmatism was 1.0 D or less (small-incision lenticule extraction: 0.26 ± 0.30D, LASEK: 0.12 ± 0.20D, P = .007) and lower for the small-incision lenticule extraction group when the preoperative astigmatism was more than 2.0 D (small-incision lenticule extraction: 0.48 ± 0.37D, LASEK: 0.89 ± 0.46D, P = .002).
  
  
  CONCLUSIONS
  An adjustment of nomograms for correcting low astigmatism (≤1.0 D) by small-incision lenticule extraction is suggested due to the tendency toward overcorrection, whereas a nomogram adjustment for tissue-saving ablation profile is needed for the correction of high astigmatism (>2.0 D) by LASEK due to the tendency toward undercorrection.
  
  
  BACKGROUND
  The authors declare that they have no competing financial interests.
authors.affiliation: From the Department of Ophthalmology (Qian, Huang, Zhou), Eye and ENT Hospital, Fudan University, Shanghai, China; Key Laboratory of Myopia of State Health Ministry (Qian, Huang, Zhou), China; Johns Hopkins University School of Medicine (Wang), Baltimore, Maryland, USA.
authors.forename: Yishan
authors.initials: Y
authors.lastname: Qian
authors.affiliation: From the Department of Ophthalmology (Qian, Huang, Zhou), Eye and ENT Hospital, Fudan University, Shanghai, China; Key Laboratory of Myopia of State Health Ministry (Qian, Huang, Zhou), China; Johns Hopkins University School of Medicine (Wang), Baltimore, Maryland, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Huang
authors.affiliation: From the Department of Ophthalmology (Qian, Huang, Zhou), Eye and ENT Hospital, Fudan University, Shanghai, China; Key Laboratory of Myopia of State Health Ministry (Qian, Huang, Zhou), China; Johns Hopkins University School of Medicine (Wang), Baltimore, Maryland, USA. Electronic address: jitong0512@163.com.
authors.forename: Xingtao
authors.initials: X
authors.lastname: Zhou
authors.affiliation: From the Department of Ophthalmology (Qian, Huang, Zhou), Eye and ENT Hospital, Fudan University, Shanghai, China; Key Laboratory of Myopia of State Health Ministry (Qian, Huang, Zhou), China; Johns Hopkins University School of Medicine (Wang), Baltimore, Maryland, USA.
authors.forename: Yutung
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D049451:Nomograms; D011184:Postoperative Period; D057234:Preoperative Period; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult