The pupillary distance, orPD for short can be thought of as the width between your eyes and where light enters into vision. It’s important because it shows exactly what part on an eyeglasses lens you look through- which means this number will determine how clear images appear!

To find out the true power of your prescription, we use a mobile app that will measure it for you! It only takes about 30 seconds to get an accurate reading, so don’t worry if there is some uncertainty at first

You usually can’t find your PD number written on your eyeglasses. The numbers on the inside of the temple arms of some frames show the measurements for the frame itself. Your PD number should be written on your eyeglass prescription in the PD section.

Your PD should be exact. If your lenses aren’t centered correctly, they can cause discomfort and eye strain. A small margin of error might not cause problems, but it’s better to be as accurate as possible.

Your PD number will be in the ‘PD’ or ‘pupillary distance’ section of your eyeglass prescription. This is often separate from the ‘grid’ section of your prescription – where the doctor writes out the main prescription information.

If your eyeglass lenses aren’t properly centered based on your PD number they can cause dizziness, headaches or blurred vision. Your vision is centered on a small section of the lenses, so a PD number is needed to shape the lenses to perfectly suit your needs.

Your PD has no effect on the size of your eyeglass frame. The PD number influences the shape of your lenses, but not the frame.

A person’s pupillary distance will change when they are young as they are still physically growing. Once we reach maturity and stop growing, our pupillary distance will change very little, if at all.

The PD number indicates exactly which part of the lens you look through; therefore, the PD number is important for every type of prescription lens, including single vision glasses.

A ‘single’ pupillary distance number is the distance in millimeters between one eye’s pupil to the other eye’s pupil. A ‘dual’ pupillary distance number is the distance in millimeters from each eye’s pupil to the center of your nose. A single PD will be just one number, while a dual PD will have a number for each eye, marked ‘right’ and ‘left’. (Some prescriptions may have ‘OD’ for the ‘right’ eye, and ‘OS’ for ‘left’ eye.)