title: A new tonometer--the Corvis ST tonometer: clinical comparison with noncontact and Goldmann applanation tonometers.
abstract: OBJECTIVE
  To compare intraocular pressure (IOP) measurements obtained using the Topocon noncontact tonometer (NCT), the Goldmann applanation tonometer (GAT), and the Corvis ST (CST), a newly developed tonometer with features of visualization and measurement of the corneal deformation response to an air impulse. A secondary objective was to assess the agreement among the devices.
  
  
  METHODS
  Fifty-nine participants, including glaucoma patients (36 cases) and control volunteers (23 cases), were enrolled. One eye was selected randomly for further study. IOP measurements were obtained with the CST, NCT, and GAT by two experienced clinicians. IOP values were compared. Intraobserver variability and interobserver variability were assessed by the coefficient of variation and intraclass correlation coefficient. Device agreement was calculated by Bland-Altman analysis.
  
  
  RESULTS
  Mean IOP for all examined eyes was 18.9 ± 5.8 mm Hg for CST, 21.3 ± 6.8 mm Hg for NCT, and 20.3 ± 5.7 mm Hg for GAT. There was no statistically significant difference in IOP measurements among the tonometers except between the CST and NCT. Correlation analysis showed a high correlation between each pair of devices (all P < 0.001). The CST displayed the best intraobserver variability and interobserver variability. Bland-Altman analysis revealed a bias between CST and GAT, CST and NCT, and GAT and NCT of -1.3, -2.4, and -1.1 mm Hg, with 95% limits of agreement of -6.2 to 3.5 mm Hg, -10.1 to 5.2 mm Hg, and -8.3 to 6.2 mm Hg, respectively.
  
  
  CONCLUSIONS
  The CST offers an alternative method for measuring IOP. IOP measurements taken with these devices may not be interchangeable.
authors: Department of Ophthalmology, Eye, Ear, Nose, and Throat Hospital, School of Shanghai Medicine, Fudan University, Shanghai, China.
authors: Jiaxu
authors: J
authors: Hong
authors: Jianjiang
authors: J
authors: Xu
authors: Anji
authors: A
authors: Wei
authors: Sophie X
authors: SX
authors: Deng
authors: Xinhan
authors: X
authors: Cui
authors: Xiaobo
authors: X
authors: Yu
authors: Xinghuai
authors: X
authors: Sun
mesh_terms: D000328:Adult; D000368:Aged; D004867:Equipment Design; D005260:Female; D005901:Glaucoma / 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; D012372:ROC Curve; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000295:instrumentation*; D055815:Young Adult