INSTRUCTIONS
A good approximation of the First Choice Base Curve for KeraSoft THIN can be calculated using the Tangential map on a topography machine. For best results, use a Normalized map with
5mm zone included and numerical values displayed. (For more information, go to the Using Tangential Topography page.)

Once you have the map, insert the steepest and flattest central Sim Ks into the calculator and then the steepest and flattest Sim Ks on the 5 mm ring and click "Calculate".

The optimal correction factor results are highlighted in orange and the calculator gives the base curve to select based on whether this is a central or low cone.

This calculation does NOT work with the Axial (Sagittal) maps, as the mid periphery values are different, nor does it work with surgically changed corneas, as the natural relationship between areas of
the cornea has been altered.




                    Please choose diopter or mm from drop down box                                                             * To be used with Tangential curvature map

                                          Measurement in:                               Enter values in mm


                  Sim K                   5mm ring

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