title: Determining in vivo biomechanical properties of the cornea with an ocular response analyzer.
abstract: OBJECTIVE
  To study the results of an ocular response analyzer (ORA) to determine the biomechanical properties of the cornea and their relationship to intraocular pressure (IOP).
  
  
  METHODS
  Reichert Inc., Depew, New York, USA.
  
  
  METHODS
  The ORA (Reichert) makes 2 essentially instantaneous applanation measurements that permit determination of corneal and IOP effects.
  
  
  RESULTS
  Measurements of several populations indicate that corneal hysteresis, a biomechanical measure, varied over a dynamic range of 1.8 to 14.6 mm Hg and was only weakly correlated with corneal thickness (r(2)=0.12); this is related to the observation that some subjects with relatively thick corneas have less-than-average corneal hysteresis. Corneal hysteresis changes diurnally, presumably as a result of hydration changes. Keratoconus, Fuchs' dystrophy, and post-LASIK patients demonstrated low corneal hysteresis.
  
  
  CONCLUSIONS
  The corneal hysteresis biomechanical measure may prove valuable for qualification and predictions of outcomes of refractive surgery and in other cases in which corneal biomechanics are important.
authors.affiliation: Reichert Inc., Depew, New York, USA. dluce@reichert.com
authors.forename: David A
authors.initials: DA
authors.lastname: Luce
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003315:Cornea / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005642:Fuchs' Endothelial Dystrophy / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007640:Keratoconus / Q000503:physiopathology; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D012030:Refractive Errors / Q000503:physiopathology