Tutorial - Measuring your PD

Monocular PD versus Binocular PD

There are two primary methods for PD measurement: single PD and dual PD. 

Binocular PD (or single PD) is the measurement from pupil to pupil between each eye.  It is a single number, between 48-72 usually.

Monocular PD (or dual PD) is the measurement from your nose bridge to each eye. It is listed as two numbers, usually separated with slash (31/32 for example).

Monocular PD is believed to be the most accurate since many people may find their nose-to-pupil measurement is not equidistant on both sides. 

PD is especially critical when fitting glasses with progressive lenses (PAL), which requires precise lens-to-pupil alignment to ensure comfortable vision at all distances.

How to measure pupillary distance 

Your eye doctor typically measures PD as part of your eye exam using a pupillary distance ruler or pupillometer, calibrated specifically to each eye. 

Watch video of how to take the PD Measurement below.  If you need a pupillary ruler you can download here.