title: Clinical evaluation of multiparameter correction equations for Goldmann applanation tonometry.
abstract: OBJECTIVE
  To evaluate and compare the multiparameter equations in correcting intraocular pressure (IOP) measurements obtained using the Goldmann applanation tonometer (IOPG) for the effects of central corneal thickness (CCT), corneal curvature (R), and age in different ethnic populations.
  
  
  METHODS
  Data of IOPG, CCT, R, and age were collected from three clinical centers. The sample size consisted of 945 eyes of 945 glaucoma patients or suspects (669 Europeans, 127 African Americans, and 149 Indians). The 'corrected IOP' was calculated using five multiparameter equations to decrease the association of CCT, R, and age with measured IOP. Regression analyses were performed to calculate variance (r(2)) and determine the association of CCT, R, and age with IOPG and corrected IOP (residual association).
  
  
  RESULTS
  Overall, CCT accounted for the majority of variance in IOPG, while R and age had a much smaller effect, with the combined effect on IOPG ranging from 4.7 to 7.5% in the three data sets. The residual association of CCT, R, and age with corrected IOP in the three groups ranged from 0.2 to 1.3% and 0.5 to 1.8% with the application of the Elsheikh and the Chihara equations, respectively. The residual association of CCT, R, and age with corrected IOP calculated using the Ehlers, Orssengo and Pye, and Shimmoyo equations were 7-11.5, 1.8-11.7, and 4.6-8.3%, respectively.
  
  
  CONCLUSIONS
  The Elsheikh and the Chihara equations better decreased the association of CCT, R, and age with measured IOP than the Ehlers, Orssengo and Pye, and Shimmoyo equations.
authors.affiliation: College of Optometry, Western University of Health Sciences, Pomona, CA 91766, USA. contact@pinakin-gunvant.com
authors.forename: P G
authors.initials: PG
authors.lastname: Davey
authors.forename: A
authors.initials: A
authors.lastname: Elsheikh
authors.forename: D F
authors.initials: DF
authors.lastname: Garway-Heath
mesh_terms: D000328:Adult; D000367:Age Factors; D003315:Cornea / Q000502:physiology*; D019781:Corneal Topography; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000706:statistics & numerical data*