Comparison of IOP measurements between ORA and GAT in normal Chinese

Kwok Cheung Andrew Lam, Davie Chen, Roger Chiu, Wan Sang Chui

Research output: Journal article publicationJournal articleAcademic researchpeer-review

75 Citations (Scopus)


PURPOSE. To compare intraocular pressure (IOP) obtained from the ocular response analyzer (ORA) and Goldmann applanation tonometer (GAT) on a group of normal Chinese. METHODS. One hundred twenty-five normal subjects were recruited, with one eye randomly selected for this study. Each eye was measured first with the noncontact tonometer ORA, followed by the GAT and ultrasound pachometry, in a randomized order. Four readings were obtained from the ORA, and three measurements were taken with the GAT. The mean was used for analysis. The ORA provided a Goldmann-correlated IOP (IOPg) and a corneal-compensated IOP (IOPcc). Three central corneal thickness (CCT) values were measured using an ultrasound pachometer, and the mean was used for analysis. RESULTS. IOP obtained from the ORA was similar to that from the GAT (IOPg minus GAT: mean difference = 0.33 mm Hg, 95% limits of agreement = 4.55 to -4.44 mm Hg; IOPcc minus GAT: mean difference = 0.24 mm Hg, 95% limits of agreement = 4.83 to -5.07 mm Hg). CCT was positively associated with corneal hysteresis (CH) (r = 0.30, p < 0.01), corneal resistance factor (r = 0.38, p < 0.01), GAT (r = 0.09, p < 0.01) and IOPg (r = 0.16, p < 0.01). IOPcc was not associated with CCT (r = 0.01, p = 0.33). CONCLUSIONS. Both IOPg and IOPcc have good agreement with GAT on normal subjects. The influence of CCT on IOPcc was insignificant.
Original languageEnglish
Pages (from-to)909-914
Number of pages6
JournalOptometry and Vision Science
Issue number9
Publication statusPublished - 1 Sept 2007


  • Corneal hysteresis
  • Corneal resistance factor
  • Corneal thickness
  • Intraocular pressure
  • Ocular response analyzer

ASJC Scopus subject areas

  • Ophthalmology


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