title: Ocular pulse amplitude in healthy subjects as measured by dynamic contour tonometry.
abstract: OBJECTIVE
  To test whether dynamic contour tonometry yields ocular pulse amplitude (OPA) measurements that are independent of corneal thickness and curvature, and to assess variables of observer agreement.
  
  
  METHODS
  In a multivariate cluster analysis on 223 eyes, the relationship between central corneal thickness, corneal curvature, axial length, anterior chamber depth, intraocular pressure, sex, age, and OPA measurements was assessed. Intraobserver and interobserver variabilities were calculated from repeated measurements obtained from 8 volunteers by 4 observers.
  
  
  RESULTS
  The OPA readings were not affected by central corneal thickness (P = .08), corneal curvature (P = .47), anterior chamber depth (P = .80), age (P = .60), or sex (P = .73). There was a positive correlation between OPA and intraocular pressure (0.12 mm Hg/1 mm Hg of intraocular pressure; P<.001) and a negative correlation between OPA and axial length (0.27 mm Hg/1 mm of length; P<.001). Intraobserver and interobserver variabilities were 0.08 and 0.02 mm Hg, respectively, and the intraclass correlation coefficient was 0.89.
  
  
  CONCLUSIONS
  The OPA readings obtained with dynamic contour tonometry in healthy subjects are not influenced by the structure of the anterior segment of the eye but are affected by intraocular pressure and axial length. We found a high amount of agreement within and between observers.
authors.affiliation: Department of Ophthalmology and Horten Centre for Patient Oriented Research, University of Zürich, Zürich, Switzerland.
authors.forename: Claude
authors.initials: C
authors.lastname: Kaufmann
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: Yves C
authors.initials: YC
authors.lastname: Robert
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thiel
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000033:anatomy & histology*; D000886:Anthropometry; D003315:Cornea / Q000033:anatomy & histology*; D005123:Eye / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015588:Observer Variation; D014065:Tonometry, Ocular / Q000295:instrumentation / Q000379:methods*