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.