Frequently Asked Questions

Measurement Parameters

  • What is Hysteresis?
  • What is the difference between viscous and elastic resistance?
  • How is Corneal Hysteresis measured?
  • What is Corneal Hysteresis
  • What is IOPg?
  • Is IOPg different from the IOP value presented by a traditional Non-Contact Tonometer (NCT)?
  • Is there a massage effect caused by repeated measurements with the Ocular Response Analyzer?
  • No. Due to the brief length of time the air-pulse is applied to the cornea, there is no massage effect.  Goldmann tonometers and other tonometers that require extended contact with the eye have been shown to have a significant massage effect.


  • What is IOPcc?
  • How is IOPcc measured?
  • What is CRF?
  • What is the range of Corneal Hysteresis in normal Subjects?
  • What is the range of Corneal Resistance Factor (CRF) in normal subjects
  • What is the average value of Corneal Hysteresis in normal subjects?
  • What is the average value of Corneal Resistance factor (CRF) in normal subjects?
  • Are CH and CRF Related to the “Modulus of Elasticity” of the cornea?
  • What is the acceptable repeat measurement variability for the corneal hysteresis measurement?
  • What is the acceptable repeat measurement variability for the corneal resistance factor (CRF) measurement?
  • Why is IOPg higher/lower than my Goldmann IOP value?
  • How do Corneal Hysteresis (CH) and Corneal Reistance Factor (CRF) differ?
  • Is Corneal Hysteresis (CH) related to Central Corneal Thickness (CCT)?
  • Interpreting results

  • What is the average value of Corneal Hysteresis in normal subjects?
  • What is the acceptable repeat measurement variability for the corneal hysteresis measurement?
  • What is the acceptable repeat measurement variability for the corneal resistance factor (CRF) measurement?
  • Why is IOPg higher/lower than my Goldmann IOP value?
  • What are the characteristics of a "good" measurement signal for a normal subject?
  • How can I tell a "bad signal" from a "good signal"?
  • Using the instrument

  • What is the acceptable repeat measurement variability for the corneal hysteresis measurement?
  • What is the acceptable repeat measurement variability for the corneal resistance factor (CRF) measurement?
  • Why is IOPg higher/lower than my Goldmann IOP value?
  • Why are the average values in the software different from the true mathematical average?
  • Where are the results saved when I use the pachymeter?
  • Should I use anesthesia before taking an Ocular Response Analyzer measurement?
  •  

    Updates

    Video - Ocular Response Analyzer Videos


    Article - The Role of Ocular Biomechanics in Glaucoma Management - Sullivan-Mee, M. (PDF)


    Webinar - Presentations are available to download


    Podcast - Gwyenth Morgan talks to Kirsten Hamilton of Cardiff University.


    © 2009 Reichert, Inc.