Measuring Pupillary Distance (PD)
The PD or Pupillary Distance is the distance between the pupils of the eyes, center to center, in millimeters. Most people have a PD between 54mm and 74mm. If you received two values, such as 31/31.5, then the values are the distance from the center of your nose to each pupil center. A PD should be provided as part of your prescription.
If you received two values, click on Dual PD and select your values - Note the RIGHT is on the left side, and LEFT is on the right. If you received a single value, then click on Single and select this value.
You may have received two PD numbers that differ by a value of 3mm (such as 62/59). The larger value represents the distance PD, which is what you will normally need for our site. The smaller value is used only for ordering single-vision reading glasses.
If your most recent eye exam did not include the PD value, but a previous one did, you can use the previous value. It does not change over time (except for children, of course).
While an optometrist's PD value is always recommended, you can determine the measurement with a friend or family member's help. Have your assistant hold a ruler just below your eyes and measure the distance in mm from pupil center to pupil center. Focus straight ahead at a distant object, and keep your eyes steady. Take a few measurements for consistency.
Do not ever guess your PD value. Also, do not try to use your current glasses to measure PD, since that is not an accurate method.