If your prescription has Cylinder (CYL) and Axis numbers, copy them exactly; they do not change for reading glasses. 2. Adjust Your Pupillary Distance (PD) PD is the distance between your pupils in millimeters.
To buy reading glasses using a prescription, you must use your distance and Addition (ADD) values to calculate the correct lens power . 1. Calculate Your Reading Power
If SPH is +1.00 and ADD is +1.75 , your reading power is +2.75 .