How to measure your pupillary distance (PD)

Single PD measures the distance between the centers of your pupils. It can be a distance PD (for most glasses) or a near PD (for reading glasses). Use distance PD for all prescription glasses except reading glasses.

Dual PD (or monocular PD) includes two measurements: from each pupil to the bridge of your nose. It's written as 32/30, where the first number is for the right eye (OD), and the second for the left eye (OS).