title: Possible Risk Factors and Clinical Effects of Opaque Bubble Layer in Small Incision Lenticule Extraction (SMILE).
abstract: OBJECTIVE
  To report the development of an opaque bubble layer (OBL) during small incision lenticule extraction (SMILE) and analyze its potential risk factors and the clinical outcome.
  
  
  METHODS
  A retrospective review of medical records was performed. The patients were divided into two groups in terms of OBL area following a posterior lenticule cut: OBL less than 5% of cornea and OBL greater than 5% of cornea. Preoperative parameters and clinical outcomes were compared. The association between amount of OBL and the various parameters was determined using a correlation analysis.
  
  
  RESULTS
  The study included 208 myopic eyes (106 patients). The incidence of OBL was 51.82% (108 eyes) and mean OBL area was 3.06% ± 4.62%. The OBL greater than 5% group (48 eyes, 23.08%) had a thicker cornea, a thinner lenticule, and a longer operation time than the OBL less than 5% group (160 eyes, 72.92%). Visual acuity, efficacy, and safety were similar between groups except for a slightly lower predictability value for the OBL greater than 5% group. The amount of OBL area presented a quantitative association with corneal thickness, lenticule thickness, and the relative vertical position of the posterior lenticular surface. Flap tear was observed in 8 eyes (3.84%), at which an extensive amount of OBL (9.76% ± 7.02%) developed.
  
  
  CONCLUSIONS
  Eyes with a thicker cornea or a thinner lenticule are more likely to develop OBL during SMILE. The OBL does not affect the overall clinical outcome. In eyes with extensive OBL, there is a higher incidence of flap tear and a lower predictability value. [J Refract Surg. 2017;33(1):24-29.].
authors.forename: Gisung
authors.initials: G
authors.lastname: Son
authors.forename: Junghyun
authors.initials: J
authors.lastname: Lee
authors.forename: Cheolwon
authors.initials: C
authors.lastname: Jang
authors.forename: Ki Yong
authors.initials: KY
authors.lastname: Choi
authors.forename: Beom Jin
authors.initials: BJ
authors.lastname: Cho
authors.forename: Tae Hyung
authors.initials: TH
authors.lastname: Lim
mesh_terms: D000328:Adult; D003318:Corneal Opacity / Q000209:etiology* / Q000503:physiopathology; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery; D048988:Corneal Surgery, Laser / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications; D008297:Male; D045423:Microbubbles; D009216:Myopia / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D012307:Risk Factors; D013524:Surgical Flaps; D014792:Visual Acuity / Q000502:physiology