title: Big-bubble deep anterior lamellar keratoplasty using central vs peripheral air injection: a clinical trial.
abstract: OBJECTIVE
  To compare 2 sites of air injection to achieve Descemet membrane (DM) detachment in big-bubble deep anterior lamellar keratoplasty (DALK).
  
  
  METHODS
  In this prospective, randomized study, 48 eyes of 48 keratoconus-affected patients who underwent DALK by cornea fellows were enrolled. Each patient was randomly assigned into one of 2 groups. After trephination to approximately 80% of the corneal thickness, a 27-G needle was inserted into the stroma from the trephination site. The needle was moved radially inside the trephination site and advanced to the central or paracentral cornea in group 1. In group 2, the needle was inserted into the deep stroma from the trephination site and advanced into the peripheral cornea to approximately 1.5 mm anterior to the limbus. Air was gently injected into the deep stroma until a big bubble was formed. The rates of DM separation and complications were compared between the 2 groups.
  
  
  RESULTS
  Big-bubble formation was successful in 79.2% of the eyes in the study group. A bare DM was achieved by central injection in 68.0% of group 1 and by peripheral injection in 69.6% of group 2 (p = 0.68). This rate was increased to 80.0% and 78.3% in groups 1 and 2, respectively, after the injection site was shifted when injections failed. The study groups were comparable in terms of complications including DM perforation and bubble bursting.
  
  
  CONCLUSIONS
  Both injection sites were equivalent in their rates of big-bubble formation and complications. Less experienced surgeons are advised to initially inject air outside the trephination.
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran - Iran.
authors.forename: Sepehr
authors.initials: S
authors.lastname: Feizi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran - Iran.
authors.forename: Seyed-Hashem
authors.initials: SH
authors.lastname: Daryabari
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran - Iran.
authors.forename: Danial
authors.initials: D
authors.lastname: Najdi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran - Iran.|Central Eye Bank of Iran, Tehran - Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Javadi
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran - Iran.|Central Eye Bank of Iran, Tehran - Iran.
authors.forename: Farid
authors.initials: F
authors.lastname: Karimian
mesh_terms: D000293:Adolescent; D000328:Adult; D000388:Air; D016039:Corneal Transplantation / Q000379:methods*; D003886:Descemet Membrane / Q000601:surgery*; D005260:Female; D006801:Humans; D007267:Injections; D007640:Keratoconus / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009339:Needles; D011446:Prospective Studies; D055815:Young Adult