What does DPD and NPD mean?
Qualified optometrist Simon Kay BSc(Hons) MCOptom answers this question.
Distance Pupillary Distance and Near Pupillary Distance. This is the distance between the centre of your pupils at distance and at near. Your distance spectacle lenses should be glazed with the optical centres the same distance between them as your DPD, and your near vision spectacles at the NPD.