Your PD, or pupillary distance, is the measurement between the centre of your pupils. It’s measured in mm and very important if you have a strong prescription or are ordering varifocal lenses, so that the optical centre of the lenses can match the wearer's PD for best vision.⁣ In this episode of our "Ask the Optician" series, David Hutchfield, Head of Professional Services and Qualified Optician, explains how we obtain your PD from selfies and what's the best way for you to send them. bit.ly/3q4