If your PD is off, the “optical center” of your lenses will be, too, and your glasses won't be as effective as they should be. You also need your prescription. Lots of optometrists will give you a copy of your prescription but not include your PD.2017-03-21
Does pupillary distance really matter?
Pupillary distance is extremely important when fitting any kind of glasses – including single vision glasses. ... Glasses lenses are designed that way for maximum effect. If the measurement is not correct, this optical centre will still be at the centre of the lens, but it won't align with your pupil.2018-05-20
What if PD is off by 2mm?
If the PD measured was 2mm off initially, by using a millimeter rule, the net cumulative error might be 4.5mm or more.