title: Interferometric technique to measure biomechanical changes in the cornea induced by refractive surgery.
abstract: OBJECTIVE
  To develop a technique to quantify biomechanical changes in the cornea after microkeratome incisions as would be performed in laser in situ keratomileusis.
  
  
  METHODS
  St Thomas' Hospital, London, and the Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, United Kingdom.
  
  
  METHODS
  Corneal displacements of whole sheep eyes were studied under hydrostatic loading using electronic speckle pattern interferometry before and after microkeratome incisions.
  
  
  RESULTS
  After hydrostatic loading, there was a 20.7% increase in corneal displacement in corneas with microkeratome incisions compared to unoperated corneas; this was statistically significant (P=.0068, unpaired t test).
  
  
  CONCLUSIONS
  Results show that in the formation of the microkeratome flap, collagen fibers are severed and minimal biomechanical loading is distributed through the flap. Corneal biomechanical integrity is compromised after microkeratome incisions.
authors.affiliation: Department of Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom. philipjaycock@hotmail.com
authors.forename: Philip David
authors.initials: PD
authors.lastname: Jaycock
authors.forename: Leon
authors.initials: L
authors.lastname: Lobo
authors.forename: Jamal
authors.initials: J
authors.lastname: Ibrahim
authors.forename: John
authors.initials: J
authors.lastname: Tyrer
authors.forename: John
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000502:physiology; D003315:Cornea / Q000502:physiology*; D019781:Corneal Topography; D003941:Diagnostic Techniques, Ophthalmological; D004547:Elastic Tissue / Q000502:physiology*; D004548:Elasticity; D006874:Hydrostatic Pressure; D007368:Interferometry / Q000379:methods*; D007429:Intraocular Pressure; D008027:Light; D012030:Refractive Errors / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012756:Sheep; D013524:Surgical Flaps
chemical_list: D003094:Collagen