This page discusses only power issues where Rx-Universe is doing the calculations (non-digital jobs).
There are only 4 factors that affect the power of a lens:
1. front curve
back curve
index of refraction
thickness of the lens
All power issues are caused by one or more of the above factors.
Front Curve
Front curves are normally expressed in diopters, which means they are expressed in a particular index. In North America, the index most often used to express curves (front curves or tool curves) is “tool index”, which is 1.530. This is set in the material table, for each material, as follows:
