title: Correlations between corneal hysteresis, intraocular pressure, and corneal central pachymetry.
abstract: OBJECTIVE
  To analyze the correlation between corneal hysteresis (CH) measured with the Ocular Response Analyzer (ORA, Reichert) and ultrasonic corneal central thickness (CCT US) and intraocular pressure measured with Goldmann applanation tonometry (IOP GA).
  
  
  METHODS
  Bordeaux 2 University, Ophthalmology Department, Bordeaux, France.
  
  
  METHODS
  This study comprised 498 eyes of 258 patients. Corneal hysteresis, corneal resistance factor (CRF), and IOP corneal-compensated (IOPcc) were provided by the ORA device; CCT US and IOP GA were also measured in each eye. The study population was divided into 5 groups: normal (n = 122), glaucoma (n = 159), keratoconus (n = 88), laser in situ keratomileusis (LASIK) (n = 78), and photorefractive keratectomy (n = 39). The Pearson correlation was used for statistical analysis.
  
  
  RESULTS
  Corneal hysteresis was not strongly correlated with IOP or CCT US. The mean CH in the LASIK (8.87 mm Hg) and keratoconus (8.34 mm Hg) groups was lower than in the glaucoma (9.48 mm Hg) and normal (10.26 mm Hg) groups. The lower the CH, the lower its correlation with IOPcc and IOP GA. A CH higher than the CRF was significantly associated with the keratoconus and post-LASIK groups.
  
  
  CONCLUSIONS
  Corneal hysteresis, a new corneal parameter, had a moderate dependence on IOP and CCT US. Weaker corneas could be screened with ORA parameters, and low CH could be considered a risk factor for underestimation of IOP. The CCT US should continue to be considered a useful parameter.
authors: Department of Ophthalmology, Bordeaux 2 University, CHU Pellegrin, Place Amélie Raba-Léon, Bordeaux, France. toubould@gmail.com
authors: David
authors: D
authors: Touboul
authors: Cynthia
authors: C
authors: Roberts
authors: Julien
authors: J
authors: Kérautret
authors: Caroline
authors: C
authors: Garra
authors: Sylvie
authors: S
authors: Maurice-Tison
authors: Elodie
authors: E
authors: Saubusse
authors: Joseph
authors: J
authors: Colin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery / Q000648:ultrastructure; D004547:Elastic Tissue / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004548:Elasticity; D005260:Female; D005901:Glaucoma / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007640:Keratoconus / Q000503:physiopathology; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D014065:Tonometry, Ocular