Q&A: How is corneal hysteresis measured?

Ahead of his technology article in the July 2022 issue of Optometry Times®, Thomas A. Wong, OD, FNAP, associate clinical professor of SUNY Optometry, and his co-authors Elise Regina, OD, and Kelly Armstrong, OD, both members of the SUNY Optometry class of 2022, discuss corneal hysteresis.

Related: Q&A: What is corneal hysteresis?

This transcript has been lightly edited for clarity:

How is corneal hysteresis measured?

Kelly Armstrong, OD:

So corneal hysteresis is measured with the ORA. It's a machine that uses applied force displacement, and it does this by using an air puff, but it's not like the infamous air puff that the NCT has used in the past a lot less aggressive.

And it's taking two measurements. So the first one flattens the cornea and applies pressure to the cornea and then the second one is the cornea kind of regaining its shape. And the difference between those two numbers is the corneal hysteresis.

Related: Corneal hysteresis and biomechanics growing in diagnostic importance