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What is PD or Pupillary Distance ?


PD, refers to the distance in millimeters between one eye’s pupil to the other eye’s pupil. It's measured in millimeters and tells the optical lab where to put the optical center on each lens. You can ask your eye doctor to include your PD on your prescription, or we can show you how to measure it by yourself.


There are two primary methods for PD measurement:

Single PD (binocular PD) is the measurement from pupil to pupil between each eye.
Dual PD (monocular PD) is the measurement from your nose bridge to each eye.

HOW TO MEASURE SINGLE PD (PUPILLARY DISTANCE):

(You’ll need a ruler with millimeter measurements and a mirror)

Step 1. Stand about 20cm away from a mirror.

Step 2. Looking at yourself, hold a ruler up against your eyebrows.

Step 3. Close your right eye, line up the ruler’s zero with your left pupil.

Step 4. Look straight ahead again and then open your right eye and close your left eye.

Step 5. Without moving your head or the ruler, mark the ruler where it lines up with your right pupil. This number is your distance single PD.

NOTE: To ensure the accuracy of the measurement, we recommend repeating the above steps 3 times to obtain a more accurate number.

HOW TO MEASURE DUAL PD (PUPILLARY DISTANCE):

(You’ll need a ruler with millimeter measurements and a mirror)

Step 1. Stand about 20cm away from a mirror.

Step 2. Looking at yourself, hold a ruler up against your eyebrows.

Step 3. Line up the ruler’s zero at the center of your nose bridge.

Step 4. Without moving your head or the ruler, mark the ruler where it lines up with your Left pupil. This number is your left eye PD.

Step 5. Repeat the same procedure with your right pupil.

NOTE: To ensure the accuracy of the measurement, we recommend repeating the above steps 3 times to obtain a more accurate number.