title: Biomechanical changes in the human cornea after transepithelial corneal crosslinking using iontophoresis.
abstract: OBJECTIVE
  To evaluate the corneal response to variable intraocular pressure (IOP) in human eye globes after ultraviolet-A (UVA) transepithelial corneal crosslinking using iontophoresis.
  
  
  METHODS
  Fondazione G.B. Bietti IRCCS, Rome, Italy.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Four human donor eye globes were treated with transepithelial crosslinking using iontophoresis and rapid UVA corneal irradiation, and 4 globes had standard crosslinking. Inflation experiments were performed on the globes before and after crosslinking. Topographic maps of the anterior and posterior cornea were acquired using Scheimpflug topography. Images were obtained using a mechanical regimen to analyze corneal strain in response to cyclic stress. Corneal shape changes were analyzed as a function of IOP, and corneal stress-strain curves were generated.
  
  
  RESULTS
  Before crosslinking, instillation of hypotonic riboflavin-5-phosphate sodium 0.1% solution using iontophoresis increased corneal thickness by 5% and instillation of dextran-enriched riboflavin 0.1% solution decreased corneal thickness by 13%. Five minutes after treatment, both crosslinking procedures reduced corneal thickness by 2%. Young's modulus (E) of the anterior cornea increased by a mean of 1.8 times (from 1.6 to 2.9 MPa) and 1.9 times (from 1.3 to 2.5 MPa) after transepithelial crosslinking using iontophoresis and standard crosslinking, respectively. The E value of the posterior cornea also increased after both procedures (mean 1.7 times versus 3.1 times).
  
  
  CONCLUSIONS
  Transepithelial crosslinking using iontophoresis increased the biomechanical strength of human corneal tissue in inflation testing of donor eye globes. The effect on corneal stiffness was almost comparable to that of standard crosslinking.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: From the Fondazione G.B. Bietti IRCCS (M. Lombardo, Serrao, Rosati, Ducoli), Vision Engineering Italy s.r.l. (G. Lombardo), Rome, and the CNR-IPCF Unit of Support of Cosenza (G. Lombardo), Rende, Italy. Electronic address: mlombardo@visioeng.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Lombardo
authors.affiliation: From the Fondazione G.B. Bietti IRCCS (M. Lombardo, Serrao, Rosati, Ducoli), Vision Engineering Italy s.r.l. (G. Lombardo), Rome, and the CNR-IPCF Unit of Support of Cosenza (G. Lombardo), Rende, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Serrao
authors.affiliation: From the Fondazione G.B. Bietti IRCCS (M. Lombardo, Serrao, Rosati, Ducoli), Vision Engineering Italy s.r.l. (G. Lombardo), Rome, and the CNR-IPCF Unit of Support of Cosenza (G. Lombardo), Rende, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Rosati
authors.affiliation: From the Fondazione G.B. Bietti IRCCS (M. Lombardo, Serrao, Rosati, Ducoli), Vision Engineering Italy s.r.l. (G. Lombardo), Rome, and the CNR-IPCF Unit of Support of Cosenza (G. Lombardo), Rende, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Ducoli
authors.affiliation: From the Fondazione G.B. Bietti IRCCS (M. Lombardo, Serrao, Rosati, Ducoli), Vision Engineering Italy s.r.l. (G. Lombardo), Rome, and the CNR-IPCF Unit of Support of Cosenza (G. Lombardo), Rende, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lombardo
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology*; D003094:Collagen / Q000378:metabolism; D003315:Cornea / Q000502:physiology*; D003319:Corneal Stroma / Q000187:drug effects* / Q000378:metabolism; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004548:Elasticity / Q000502:physiology; D019573:Epithelium, Corneal; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007478:Iontophoresis; D008875:Middle Aged; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use; D014019:Tissue Donors; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin