title: Factors influencing intermethod agreement between goldmann applanation, pascal dynamic contour, and ocular response analyzer tonometry.
abstract: OBJECTIVE
  To examine factors that influence intraocular pressure (IOP) measurement agreement between Goldmann applanation (GAT), Ocular Response Analyzer (ORA), and Pascal Dynamic Contour tonometers (DCT).
  
  
  METHODS
  In subjects who were diagnosed with primary open-angle glaucoma, ocular hypertension, glaucoma suspect, and normal, we used ORA, DCT, and GAT to obtain corneal hysteresis (CH), corneal resistance factor (CRF), ocular pulse amplitude, and 4 IOP values (ORA-IOPcc; ORA-IOPg; DCT-IOP; and GAT-IOP.) We also obtained corneal curvature, corneal thickness, axial length, retinal nerve fiber layer thickness, visual field parameters, diabetes diagnostic status, and topical IOP-lowering treatment data. Analysis of variance, Bland-Altman, and regression analyses were used to examine IOP agreement and associated factors.
  
  
  RESULTS
  In 243 eyes of the 243 subjects, mean DCT-IOP (18.73±4.92) was not different from mean ORA-IOPcc (18.96±5.41) but both were significantly higher than ORA-IOPg (16.97±5.49) and GAT-IOP (16.37±4.97). In multivariate regression models, intermethod differences between IOPg, IOPcc, and DCT-IOP were explained almost completely by variations in CH, CRF, and level of IOP (r(2)=0.98 to 0.99); conversely, intermethod variability between GAT-IOP and the other 3 IOP metrics was only partially explained by the factors evaluated in this study (r(2)=0.31 to 0.65).
  
  
  CONCLUSIONS
  Consistent with other studies, we found that the 4 IOP variables examined in this study are not interchangeable. The most consistent confounders of IOP measurement agreement were the ORA-measured corneal parameters, CH and CRF. Thus, accounting for these factors may be important in efforts to obtain accurate transcorneal estimates of IOP.
authors.affiliation: Albuquerque VA Medical Center, Albuquerque, NM 87108, USA. Michael.Sullivan-Mee@va.gov
authors.forename: Michael
authors.initials: M
authors.lastname: Sullivan-Mee
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Lewis
authors.forename: Denise
authors.initials: D
authors.lastname: Pensyl
authors.forename: Gretchen
authors.initials: G
authors.lastname: Gerhardt
authors.forename: Kathy D
authors.initials: KD
authors.lastname: Halverson
authors.forename: Clifford
authors.initials: C
authors.lastname: Qualls
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005123:Eye / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis* / Q000503:physiopathology; D011446:Prospective Studies; D015203:Reproducibility of Results; D013997:Time Factors; D014065:Tonometry, Ocular / Q000379:methods*; D014794:Visual Fields