title: Effect of femtosecond laser setting on visual performance after small-incision lenticule extraction for myopia.
abstract: OBJECTIVE
  To compare the effect of the two femtosecond laser settings on visual performance after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism.
  
  
  METHODS
  Forty-four eyes of 22 consecutive patients who underwent SMILE with an energy level of 140 nJ (spot distance 3.0 µm) in one eye, and with an energy level of 170 nJ (spot distance 4.5 µm) in the other eye, the eyes being randomly assigned. Preoperatively, 1 week, and 1 and 3 months postoperatively, the values of the modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI) and Optical Quality Analysis System (OQAS) values (OVs) for these eyes were quantitatively assessed using an Optical Quality Analysis System (Visiometrics).
  
  
  RESULTS
  No significant differences were detected between the two groups in the visual and refractive outcomes, or in the MTF cutoff frequency, the Strehl ratio, the OSI, the OV 100%, the OV 20% or the OV 9% at any time point before or after surgery.
  
  
  CONCLUSIONS
  SMILE with energy settings of 140 and 170 nJ was effective for the correction of myopia and myopic astigmatism. It is indicated that the differences in laser setting (140 nJ, spot distance 3.0 µm vs 170 nJ, spot distance 4.5 µm) did not significantly affect the optical quality including the intraocular scattering of eyes undergoing SMILE.
  
  
  BACKGROUND
  The protocol was registered with University Hospital Medical Information Network Clinical Trial Registry (UMIN000016241).
authors: Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan.
authors: Kazutaka
authors: K
authors: Kamiya
authors: Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan.
authors: Kimiya
authors: K
authors: Shimizu
authors: Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan.
authors: Akihito
authors: A
authors: Igarashi
authors: Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan.
authors: Hidenaga
authors: H
authors: Kobashi
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular; D014792:Visual Acuity
keywords: Treatment Lasers