title: Modified big-bubble technique compared to manual dissection deep anterior lamellar keratoplasty in the treatment of keratoconus.
abstract: OBJECTIVE
  To evaluate the clinical findings and results of manual dissection deep anterior lamellar keratoplasty (DALK) compared to a modified big-bubble DALK technique in eyes affected by keratoconus.
  
  
  METHODS
  Sixty eyes of 60 patients with keratoconus were treated with one of the two surgical techniques manual DALK (n = 30); big-bubble DALK (n = 30). The main outcomes measured were visual acuity, corneal topographic parameters, thickness of residual stroma and endothelial cell density (ECD). Patients were examined postoperatively at 1 month, 6 months, 1 year and 1 month after suture removal.
  
  
  RESULTS
  Final best spectacle-corrected visual acuity (BSCVA) measured 1 month after suture removal was 0.11 ± 0.08 LogMAR in the big-bubble group compared to 0.13 ± 0.08 in the manual DALK group (p = 0.227). In patients treated with the big-bubble technique without complications (Descemet's membrane completely bared), the stromal residue was not measureable. Mean stromal residual thickness in the manual DALK group was 30.50 ± 27.60 μm. Data analysis of the manual DALK group demonstrated a significant correlation between BSCVA and residual stromal thickness; lower residual stromal thickness correlated with better BSCVA values (Spearman ρ = 0.509, p = 0.018). Postoperative ECD was similar in both groups at all intervals, with no statistically significant differences. In both groups, ECD loss was only significant during the 1- to 6-month interval (p = 0.001 and p < 0.001 in the big-bubble DALK and manual DALK groups, respectively).
  
  
  CONCLUSIONS
  Manual DALK provides comparable results to big-bubble DALK. Big-bubble DALK permits faster visual recovery and is a surgical technique, which can be easily converted to manual DALK in cases of unsuccessful 'big-bubble' formation.
authors.affiliation: Department of Ophthalmology, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Karl Anders
authors.initials: KA
authors.lastname: Knutsson
authors.affiliation: Cornea and Ocular Surface Unit, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Rama
authors.affiliation: Cornea and Ocular Surface Unit, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Paganoni
mesh_terms: D000328:Adult; D002452:Cell Count; D003319:Corneal Stroma / Q000033:anatomy & histology; D019781:Corneal Topography; D016039:Corneal Transplantation / Q000379:methods*; D004210:Dissection / Q000379:methods*; D004728:Endothelium, Corneal / Q000166:cytology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
keywords: big bubble; deep anterior lamellar keratoplasty; keratoconus; keratoplasty