What Is Pupillary Distance(PD)?
Pupillary Distance (PD) is the distance, in millimeters, between the center of one pupil to the center of the other. Your PD is an important factor inensuring that the center of each lens goes dirctly over your purpils. For people with hight-powered lenses, this is especially important.
We highly recommend checking your PD with your doctor, especially for bifocal or progressive lenses.
If you don't have it, here's how you can measure it yourself.
Here are the basic steps for measuring your PD:
Stand in front of a mirror (about 12 inches away).
Hold a millimeter ruler horizontally, just above your eyes and flat against your eyebrows.
Close your right eye.
With your left eye, align the ruler’s zero mark to the center of the pupil of your left eye.
Without moving the ruler, close your left eye and open your right eye.
Find the millimeter mark on the ruler that is aligned with the center of the pupil of your right eye. Record this measurement. This is your distance binocular PD.
For reading glasses, subtract 3 mm from your distance binocular PD. This is your near PD.
You may want to repeat these steps a few times to ensure you are consistent with your PD measurements.