This calculator is intended for calculation of correct Reduction (Dregression) of reader lenses, to offer customers best possible view on intermediate distance (monitor, work area, …) and near distance.
1. Distance prescription values and Addition.
2. Use one of two ways to determine the correct Reduction:
A. Enter Reduction to calculate the Intermediate viewing distance.
B. Enter Intermediate viewing distance to calculate the Reduction.
In each case you will get also prescription values for upper (intermediate distance) and lower (near or reading) part of lens.