title: Quantitative Analysis of Corneal Energy Dissipation and Corneal and Orbital Deformation in Response to an Air-Pulse in Healthy Eyes.
abstract: OBJECTIVE
  To examine and evaluate ocular biomechanical metrics and additionally derived corneal and orbital components using a noncontact Scheimpflug-based tonometer (CorVis ST) in a population of healthy eyes.
  
  
  METHODS
  A total of 152 eyes of 152 participants were examined by slit-lamp biomicroscopy, corneal tomography, and the CorVis ST (CST). This determined the distribution of outputs from the CST, such as deformation amplitude (DA), and additionally derived parameters, including maximum corneal deformation (MCD), maximum orbital deformation (MOD), and corneal energy dissipation (CED).
  
  
  RESULTS
  The mean age of participants was 35.88 ± 13.8 years. Deformation amplitude significantly correlated with age (r = 0.24, P = 0.002) but not sex or ethnicity (P > 0.05). Multiple linear regression analysis revealed significant correlations between DA and age (r = 0.19, P = 0.006) and DA and IOP (r = -0.59, P < 0.001). Age correlated with MCD (r = 0.20, P = 0.01), MOD (r = 0.18, P = 0.03), and CED (r = 0.39, P < 0.001). Males had a lower MOD than females (0.24 vs. 0.26 mm, respectively, P = 0.01); however, there were no differences in MCD or CED between sexes (P > 0.05). There were no significant differences between ethnicities for MCD, MOD, and CED (P > 0.05). Multiple linear regression analysis revealed significant correlations between MCD and IOP (r = -0.65, P < 0.001), CED and age (r = 0.41, P < 0.001), CED and IOP (r = 0.28, P = 0.001), and between CED and central corneal thickness (CCT) (r = -0.36, P < 0.001).
  
  
  CONCLUSIONS
  The isolation of the corneal component (MCD) should be used when analyzing deformation characteristics in diseases that only affect the cornea. This study establishes a baseline for a population of healthy eyes. Future publications will identify differences in MCD, MOD, and CED between healthy and diseased populations.
authors.affiliation: Department of Ophthalmology New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Hans R
authors.initials: HR
authors.lastname: Vellara
authors.affiliation: Department of Ophthalmology New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Noor Q
authors.initials: NQ
authors.lastname: Ali
authors.affiliation: Department of Ophthalmology New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Akilesh
authors.initials: A
authors.lastname: Gokul
authors.affiliation: School of Optometry and Visual Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: Jason
authors.initials: J
authors.lastname: Turuwhenua
authors.affiliation: Department of Ophthalmology New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Dipika V
authors.initials: DV
authors.lastname: Patel
authors.affiliation: Department of Ophthalmology New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Charles N J
authors.initials: CN
authors.lastname: McGhee
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D003315:Cornea / Q000502:physiology*; D004548:Elasticity / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D066167:Slit Lamp; D014065:Tonometry, Ocular; D055815:Young Adult