What is This Funny Looking Ruler?

You’ve just picked up your mail and you can’t be more thrilled to see your EyeQue Personal Vision Tracker has arrived! You tear into the package with anticipation and find not only your new miniscope, but a funky looking ruler. What in the???



Here’s the story.

It’s called a PD ruler and it’s used to measure your pupillary distance. Like the name suggests, pupillary distance is the distance between your pupils, the black center dots in your eye, measured in millimeters (mm). Most adults have a pupillary distance of 54mm to 74mm, center to center.


Why do I need to know my pupillary distance?
Your PD measurement is an important part of ordering glasses, online or in person.

How do I use it?
Place the PD ruler over your nose, resting it gently against your face, and add up the distance from both sides.




There are several ways to measure your PD:

  1. If you have a friend, hold the ruler against your face, touching your nose bridge, and have them read off the two numbers at the center of your pupils.
  2. Hold the ruler gently against your face and take a selfie! Make sure that you use flash to see where your pupils are.
  3. Use the back side of the ruler, hold it up gently against your face, and look into the mirror. You will notice that the back side of the ruler is printed backwards for this purpose.
  4. For more instructions, watch this video by clicking here or copy & pasting this link: https://www.youtube.com/watch?v=qk3YzucfVl4

The good news is, once you’ve measured your PD once, you won’t need it for a while. Alternative uses include book marker, ruler in mm, and superhero mask.

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Pupillary Distance: One Little Number That Can Make or Break Your Glasses?