December 2015
Volume 56, Issue 13
Letters to the Editor  |   December 2015
Author Response: Dimensional and Flow Properties of the EX-PRESS Glaucoma Drainage Device
Author Affiliations
  • Arsham Sheybani
    Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, United States; and the
  • Iqbal Ike K. Arsham
    Department of Ophthalmology and Visual Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.
Investigative Ophthalmology & Visual Science December 2015, Vol.56, 8027. doi:
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Arsham Sheybani, Iqbal Ike K. Arsham; Author Response: Dimensional and Flow Properties of the EX-PRESS Glaucoma Drainage Device. Invest. Ophthalmol. Vis. Sci. 2015;56(13):8027. doi:

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements
We appreciate the comments by Lee et al.1 Our study is in agreement with the findings of the authors regarding the minimal outflow resistance provided by the EX-PRESS device. This is why it must be placed beneath a scleral flap. 
The authors are correct in pointing out that the Hagen-Poiseuille (HP) law is not applicable to the EX-PRESS device. We would like to point out that our original manuscript does not apply these laws to the device. We studied the device ex vivo and did not use the HP equation to calculate the resistance through the EX-PRESS device. 
The purpose of our flow studies was to compare valveless devices under the same conditions. The HP equation was used in the design of the gel stent as detailed in the manuscript. It was not used to comment on flow through the other devices tested. 
Lee RMH, Samsudin A, Bouremel Y, Brocchini S, Khaw PT. Dimensional and flow properties of the EX-PRESS glaucoma drainage device. Invest Ophthalmol Vis Sci. 2015; 56: 8026.

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.