title: Ultraviolet A: Visible spectral absorbance of the human cornea after transepithelial soaking with dextran-enriched and dextran-free riboflavin 0.1% ophthalmic solutions.
abstract: OBJECTIVE
  To evaluate the stromal concentration of 2 commercially available transepithelial riboflavin 0.1% solutions in human donor corneas with the use of spectrophotometry.
  
  
  METHODS
  University of Calabria, Rende, Italy.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  The absorbance spectra of 12 corneal tissues were measured in the 330 to 700 nm wavelength range using a purpose-designed spectrophotometry setup before and after transepithelial corneal soaking with a 15% dextran-enriched riboflavin 0.1% solution (n = 6) or a hypotonic dextran-free riboflavin 0.1% solution (n = 6). Both ophthalmic solutions contained ethylenediaminetetraacetic acid and trometamol as enhancers. In addition, 4 deepithelialized corneal tissues underwent stromal soaking with a 20% dextran-enriched riboflavin 0.1% solution and were used as controls. All the riboflavin solutions were applied topically for 30 minutes. The stromal concentration of riboflavin was quantified by analysis of absorbance spectra of the cornea collected before and after application of each solution.
  
  
  RESULTS
  The mean stromal riboflavin concentration was 0.012% ± 0.003% (SD), 0.0005% ± 0.0003% (P < .001), and 0.004% ± 0.001% (P < .01) in tissues soaked with 20% dextran-enriched, 15% dextran-enriched, and hypotonic dextran-free solutions, respectively. The difference of stromal riboflavin concentration between the 2 transepithelial solutions was statistically significant (P < .01).
  
  
  CONCLUSIONS
  Dextran-enriched solutions required complete corneal deepithelialization to permit effective stromal soaking with riboflavin. Nevertheless, riboflavin in hypotonic dextran-free solution with enhancers permeates across stroma through an intact epithelium.
  
  
  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), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, 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), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Norberto
authors.initials: N
authors.lastname: Micali
authors.affiliation: From the Fondazione G.B. Bietti-IRCCS (M. Lombardo, Serrao), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Villari
authors.affiliation: From the Fondazione G.B. Bietti-IRCCS (M. Lombardo, Serrao), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Serrao
authors.affiliation: From the Fondazione G.B. Bietti-IRCCS (M. Lombardo, Serrao), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pucci
authors.affiliation: From the Fondazione G.B. Bietti-IRCCS (M. Lombardo, Serrao), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Barberi
authors.affiliation: From the Fondazione G.B. Bietti-IRCCS (M. Lombardo, Serrao), Vision Engineering Italy srl (G. Lombardo), Rome, Consiglio Nazionale delle Ricerche-Istituto per i Processi Chimico Fisici (Micali, Villari, G. Lombardo), Messina, and the Department of Physics (Pucci, Barberi), University of Calabria, Rende, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lombardo
mesh_terms: D000368:Aged; D001692:Biological Transport; D003319:Corneal Stroma / Q000378:metabolism* / Q000528:radiation effects; D003646:Debridement; D003911:Dextrans / Q000493:pharmacokinetics*; D019573:Epithelium, Corneal / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D009883:Ophthalmic Solutions; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000493:pharmacokinetics*; D012256:Riboflavin / Q000493:pharmacokinetics*; D014019:Tissue Donors; D014466:Ultraviolet Rays
chemical_list: D003911:Dextrans; D009883:Ophthalmic Solutions; D017319:Photosensitizing Agents; D012256:Riboflavin