title: Outcomes of deep anterior lamellar keratoplasty for keratoconus:  learning curve and advantages of the big bubble technique.
abstract: OBJECTIVE
  To evaluate retrospectively the outcomes of a case series of deep anterior lamellar keratoplasties by air dissection (DALK-AD) using the big bubble (BB) technique, in the surgical treatment of keratoconus (KC).
  
  
  METHODS
  Forty-four consecutive keratoplasties of 42 patients for KC were performed at the French National Reference Center for KC from January 2008 to June 2010 by the same surgeon with the aim of systematically performing DALK-AD with the BB technique. The outcomes of the DALK-AD not converted to penetrating keratoplasty were analyzed, and a learning curve was established to successfully achieve the DALK-AD using the BB technique.
  
  
  RESULTS
  Thirty-two DALK-AD procedures were successfully performed among 44 consecutively operated keratoplasties, with 12 being converted to penetrating keratoplasty during the surgical procedure. At 12 months, the mean best-corrected logarithm of the minimum angle of resolution visual acuity was 0.88 ± 0.14 with 93.3% seeing best-corrected visual acuity ≥ 20/30 and 100% seeing best-corrected visual acuity ≥ 20/40. The mean gain of visual acuity in logarithm of the minimum angle of resolution lines at 6 and 12 months was 6.12 ± 3.97 (P < 0.0001) and 6.94 ± 4.18 (P < 0.005), respectively. The rate for intraoperative and postoperative complications was 31.8% and 4.5%, respectively.
  
  
  CONCLUSIONS
  Despite a learning period needed to successfully perform deep lamellar anterior keratoplasty with the BB technique, this approach is safe and provides very good visual outcomes when adequate baring of Descemet membrane is achieved. The learning curve showed that complications related to this technique decrease significantly after the first 10 cases.
authors.affiliation: National Reference Center for Keratoconus, Bordeaux University Hospital, Bordeaux, France. davidsmadj@hotmail.fr
authors.forename: David
authors.initials: D
authors.lastname: Smadja
authors.forename: Joseph
authors.initials: J
authors.lastname: Colin
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Krueger
authors.forename: Glauco R
authors.initials: GR
authors.lastname: Mello
authors.forename: Anne
authors.initials: A
authors.lastname: Gallois
authors.forename: Bruno
authors.initials: B
authors.lastname: Mortemousque
authors.forename: David
authors.initials: D
authors.lastname: Touboul
mesh_terms: D000293:Adolescent; D000328:Adult; D016039:Corneal Transplantation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007431:Intraoperative Complications; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult