title: Repeatability of ocular response analyzer metrics: a gender-based study.
abstract: OBJECTIVE
  To assess the repeatability of Goldmann-correlated intraocular pressure (IOPG), corneal-compensated IOP (IOPCC), corneal hysteresis (CH), and the corneal resistance factor (CRF) obtained with the Ocular Response Analyzer (ORA) in normal eyes and to determine whether any differences in corneal biomechanical parameters or their repeatability exist between the sexes.
  
  
  METHODS
  A prospective observational study assessing 100 normal adults (50 men and 50 women; median age, 54.5 years). Comparison of ORA parameters measured in both eyes in three sets of four consecutive readings by one examiner within a 30-minute period.
  
  
  RESULTS
  The mean values of the ORA parameters assessed, the intraclass correlation coefficient (ICC) and the coefficient of repeatability (CR), were as follows for the right eye (n = 100): IOPG, 16.2 ± 3.3 mm Hg (ICC, 0.96; CR, 6.37); IOPCC, 16.2 ± 3.2 (ICC, 0.94; CR, 6.29); CRF, 10.9 ± 1.9 (ICC, 0.91; CR, 3.62); CH, 10.6 ± 1.7 (ICC, 0.94; CR, 3.37). The ICC between the readings was excellent (>0.9) for all the ORA parameters in both sexes, with the exception of one group (female CRF ICC, 0.86). Coefficient of repeatability of the instrument satisfies the British Standards Institution criteria for repeatability. There were no significant differences between corneal biomechanical factors and IOP results for men and women.
  
  
  CONCLUSIONS
  Corneal biomechanical parameters measured by the ORA provide repeatable results in normal eyes, with no significant difference between the sexes.
authors.affiliation: Department of Ophthalmology, Nottingham University Hospitals NHS Trust, Queens Medical Centre, Nottingham, United Kingdom.
authors.forename: Vinoo Philip
authors.initials: VP
authors.lastname: David
authors.forename: Richard E
authors.initials: RE
authors.lastname: Stead
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Vernon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000502:physiology*; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012737:Sex Factors; D014065:Tonometry, Ocular / Q000379:methods; D055815:Young Adult