I'm trying to create a SRAX attribute to help with keratoconus diagnosis. I've created a new attribute, called it SRAX, and have entered the formula:

abs ( Zone3mmSteep2Angle() -180- Zone3mmSteep1Angle() )

My problem is, I know the SRAX is the degrees of skew between the steepest meridians above & below the horizontal, but I suspect (know) my formula above is not the right formula to do that... can someone help with a formula to calculate SRAX please?