title: Bowman layer transplantation to reduce and stabilize progressive, advanced keratoconus.
abstract: OBJECTIVE
  To evaluate the clinical outcome of mid-stromal isolated Bowman layer transplantation, a new surgical technique to reduce and stabilize ectasia in eyes with advanced keratoconus, to postpone penetrating keratoplasty or deep anterior lamellar keratoplasty, and to enable continued daily contact lens wear.
  
  
  METHODS
  Prospective, nonrandomized cohort study at a tertiary referral center.
  
  
  METHODS
  Twenty-two eyes of 19 patients with progressive, advanced keratoconus not eligible for ultraviolet cross-linking.
  
  
  METHODS
  The mid-stroma was manually dissected and an isolated donor Bowman layer was positioned within the stromal pocket.
  
  
  METHODS
  Before and up to 36 months after surgery (mean follow-up, 21±7 months), best spectacle-corrected visual acuity (BSCVA), best contact lens-corrected visual acuity (BCLVA), Scheimpflug-based corneal tomography measurements, endothelial cell density, biomicroscopy, refraction, and intraoperative and postoperative complications were recorded.
  
  
  RESULTS
  Two surgeries were complicated by an intraoperative perforation of Descemet membrane; no other intraoperative or postoperative complications were observed. Maximum keratometry decreased on average from 77.2±6.2 diopters (D) to 69.2±3.7 D (P < 0.001) at 1 month after surgery and remained stable thereafter (P ≥ 0.072). Mean BSCVA improved from 1.27±0.44 logarithm of the minimum angle of resolution units before surgery to 0.90±0.30 logarithm of the minimum angle of resolution units 12 months after surgery (P < 0.001), whereas BCLVA remained stable (P = 0.105). Mean thinnest-point pachymetry increased from 332±59 μm before surgery to 360±50 μm at the latest follow-up (P = 0.012), and no change in endothelial cell density was found (P = 0.355).
  
  
  CONCLUSIONS
  With isolated Bowman layer transplantation, reduction and stabilization of corneal ectasia was achieved in eyes with progressive, advanced keratoconus. Given the low risk for complications, the procedure may be performed to postpone penetrating or deep anterior lamellar keratoplasty.
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Melles Cornea Clinic, Rotterdam, the Netherlands.
authors.forename: Korine
authors.initials: K
authors.lastname: van Dijk
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Melles Cornea Clinic, Rotterdam, the Netherlands.
authors.forename: Vasilios S
authors.initials: VS
authors.lastname: Liarakos
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Melles Cornea Clinic, Rotterdam, the Netherlands; Callahan Eye Hospital, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Jack
authors.initials: J
authors.lastname: Parker
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Melles Cornea Clinic, Rotterdam, the Netherlands; Amnitrans EyeBank, Rotterdam, the Netherlands.
authors.forename: Lisanne
authors.initials: L
authors.lastname: Ham
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Amnitrans EyeBank, Rotterdam, the Netherlands.
authors.forename: Jessica T
authors.initials: JT
authors.lastname: Lie
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Amnitrans EyeBank, Rotterdam, the Netherlands.
authors.forename: Esther A
authors.initials: EA
authors.lastname: Groeneveld-van Beek
authors.affiliation: Netherlands Institute for Innovative Ocular Surgery, Rotterdam, the Netherlands; Melles Cornea Clinic, Rotterdam, the Netherlands; Amnitrans EyeBank, Rotterdam, the Netherlands. Electronic address: research@niios.com.
authors.forename: Gerrit R J
authors.initials: GR
authors.lastname: Melles
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D050541:Bowman Membrane; D015331:Cohort Studies; D003315:Cornea / Q000503:physiopathology; D063171:Corneal Pachymetry; D019781:Corneal Topography; D016039:Corneal Transplantation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012029:Refraction, Ocular; D014019:Tissue Donors; D020858:Tissue and Organ Harvesting / Q000379:methods; D014792:Visual Acuity; D055815:Young Adult