title: Pentacam-based big bubble deep anterior lamellar keratoplasty in patients with keratoconus.
abstract: OBJECTIVE
  To describe the clinical results of Pentacam-based big bubble deep anterior lamellar keratoplasty (DALK) to achieve an intended 90% depth of initial lamellar trephination.
  
  
  METHODS
  Fifty consecutive eyes of 50 patients with keratoconus, keratoglobus, and anterior stromal scars were included. DALK was performed with the big bubble technique using a 90% intended depth for initial lamellar trephination based on preoperative pachymetry by Pentacam. Main outcome measures were success of surgery, best spectacle-corrected visual acuity, endothelial cell count, refractive astigmatism at 12-month follow-up, and rate of intra- and postoperative complications.
  
  
  RESULTS
  In 84% of the patients (n = 42), Pentacam-based big bubble DALK could be performed successfully. Successful big bubble formation could be achieved in 80% of the patients (n = 34). In case of macroperforation (n = 8), surgery was converted to standard penetrating keratoplasty representing a conversion rate of 16%. Intraoperative microperforation (n = 5) could be handled by an intracameral air injection at the end of operation with successful completion of the lamellar procedure. No allograft rejection was observed. Best spectacle-corrected visual acuity improved from 20/125 ± 20/160 preoperatively to 20/40 ± 20/80 at 12-month follow-up. Endothelial cell count was 2102 ± 318 cells per square millimeter preoperatively and 1735 ± 420 cells per square millimeter at 12-month follow-up. Refractive astigmatism was 7.09 ± 3.13 diopters preoperatively and decreased to 4.13 ± 2.41 diopters.
  
  
  CONCLUSIONS
  Pentacam-based big bubble DALK using a 90% intended depth of initial lamellar trephination seems to be a safe and effective procedure for anterior corneal stromal disorders such as keratoconus. We suggest that Pentacam-based depth assessment allows for reliably deep initial preparation and may allow more successful bubble formation in DALK surgery.
authors.affiliation: Department of Ophthalmology and Eye Hospital, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Riss
authors.forename: Ludwig M
authors.initials: LM
authors.lastname: Heindl
authors.forename: Bjoern O
authors.initials: BO
authors.lastname: Bachmann
authors.forename: Friedrich E
authors.initials: FE
authors.lastname: Kruse
authors.forename: Claus
authors.initials: C
authors.lastname: Cursiefen
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000503:physiopathology; D002452:Cell Count; D019781:Corneal Topography; D016039:Corneal Transplantation / Q000379:methods*; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006085:Graft Survival / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology