title: Measurement of corneal changes after collagen crosslinking using a noninvasive ultrasound system.
abstract: OBJECTIVE
  To determine the changes in corneal properties induced by riboflavin-ultraviolet A (UVA) irradiation using a noninvasive ultrasound (US) method in a porcine eye model.
  
  
  METHODS
  Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, USA.
  
  
  METHODS
  Fresh porcine globes acquired within 24 hours postmortem were divided into equal groups. In the collagen crosslinking (CXL) group, the globes were irradiated with UVA in combination with riboflavin application following the standard protocol. The control group had the same procedures as the CXL group but with no UVA irradiation. Corneal properties were measured before and after treatments in both groups using a quantitative US method. Changes in corneal thickness, density, and stiffness were examined and the difference between the changes in the CXL group and the control group was analyzed.
  
  
  RESULTS
  Each group comprised 14 porcine globes. After riboflavin-UVA treatment, there was a significant increase in corneal stiffness (mean 2.59 +/- 0.08 GPa before and 2.70 +/- 0.08 GPa after CXL) (P<.001) and in the speed of sound in corneal tissue (1557 +/- 23 m/s versus 1588 +/- 22 m/s) (P<.001). There was no significant change in corneal stiffness or in the speed of sound in the control group. Corneal thickness increased significantly after the treatment in both groups. No significant change in corneal density was observed in either group.
  
  
  CONCLUSIONS
  Corneal stiffness increased after riboflavin-UVA CXL, a finding detected using a noninvasive US technique.
  
  
  BACKGROUND
  Dr. Liu has filed a patent application for the general ultrasound technique used in the study. No other author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: Department of Biomedical Engineering, Ohio State University, Columbus, Ohio, USA.
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: He
authors.forename: Eberhard
authors.initials: E
authors.lastname: Spoerl
authors.forename: Junhua
authors.initials: J
authors.lastname: Tang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism*; D003319:Corneal Stroma / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D004548:Elasticity; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D012256:Riboflavin / Q000494:pharmacology*; D013552:Swine; D014463:Ultrasonography; D014466:Ultraviolet Rays
chemical_list: D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin