The Base Curve Calculator is to be used with the Tangential Curvature topography map with Sim Ks and 5mm zone included and numerical values displayed.
Insert Sim Ks and flattest & steepest values from the 5mm ring and click Calculate
Please choose diopter or mm from drop down box

Measurement in: Enter values in mm              * To be used with Tangential curvature map
Steep (Sim K)
Flat (Sim K)
Steep (5mm ring)
Flat (5mm ring)

Use correction factor 1.30 if K Reading is under 7mm and over 48.21D.
Use correction factor 0.8 if K reading is over 7mm and under 48.21D.