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PD MEASUREMENT


Pupillary Distance (PD) is the distance between the center of one pupil to the center of the other pupil, measured in millimeters. Your PD values can be written as one number (known as Binocular PD) if the left and right side have been added together or two numbers (known as Monocular PD) if they are different. E.g. 65 or 32/33

Adding the two Monocular PD values together will always equal the Binocular PD. However, Monocular PD values cannot be reliably achieved by dividing the Binocular PD in half. Faces are rarely perfectly symmetrical, and it is common for one eye to be further from the nose bridge than the other. Because Monocular PD values are more precise, they are required for Progressive and Bifocal lenses.

Why Pupillary Distance (PD) measurement is so important is that every eyeglasses prescription has an optical center. The optical center of your eyeglass lenses is the part that gives you the best vision, and it should be directly in front of your pupils. So how to tell where is the optical center that is specifically for you, that's customized for your eyes? That's when your PD comes in place and your eyeglasses laboratory would need to know it.

So how to measure your PD? Now it's easier than ever! Simply use our 3D Try On feature, real time! You get your PD measurement right away, any day, any time. This is a special feature Glasses Gallery innovatively created for you. We'd like to furnish your optical needs with our state-of-the-art technology, from PD measurement to frames picking, you can count on us to give you the best support.

However, if you like to measure it manually, the most common way is shown below.



Steps to measure your PD

STEP 1

Facing the mirror with the measuring distance of about 50cm, place the ruler on the bridge of your nose. Remember the start of the ruler (the zero scale) should be placed directly below the center of one eye's pupil.

STEP 2

Looking straight into the mirror, hold the ruler and mark the location on the ruler the center of the other eye's pupil.

STEP 3

Measure the distance in millimeters between the two marks. This is your PD.

STEP 4

Repeat the process two or three times for accuracy.

STEP 5

Record your results.

Remember you always need to keep your ruler steady and parallel to the floor using this method. If you have a friend to help, this will be much easier. You only need to stand still and let your friend do the measurement.

There's another PD measurement method which is claimed to be very accurate. Posted here also for your reference:

  1. Wear your glasses. (Any glasses will do)
  2. Have a marker ready.
  3. Focus on a single object at least 20 feet away.
  4. Use your marker, on your right lens, precisely put a dot directly over the distant object.
  5. Repeat for your left eye.
  6. This is the important step. Now with both eyes open, the two dots should overlap into one single dot. If not, repeat steps 4 and 5 until you get one overlapped dot.
  7. Then, measure the distance between the two dots on your lenses with a ruler.
  8. That's your distance PD!
  9. For those who need a near PD for reading or computer glasses, simply do the same but the object you choose is exactly the one you will be looking at, say, a newspaper, or a computer screen.

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