Measuring your PD

GlassesUSA.com is proud to be the one-stop-shop for our customers prescription eyeglasses, purchasing glasses online but we are also happy to be the place that customers go for information on all things vision-related. We pride ourselves on giving accurate information to all of our customers’ questions in our answers. On such question that came to us recently gave us the idea to revamp the concept of measuring your pupillary distance (PD).

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• So, what is your pupillary distance?
• Why have your pupillary distance measured?
• Where do you find out your pupillary distance?
• Measuring your pupillary distance on your own

So, what is your pupillary distance?

Well, it is the distance between the center of the pupil in your left eye to the center of the pupil in your right eye – or vice versa.

Why have your pupillary distance measured?

Prescription glasses are best made with a PD. Glasses are made so that the distance between your pupils matches the distance between the optical centers of the lenses in your glasses. If the centers are not matched up properly, eyeglass wearers can have a few optical problems like blurry vision and headaches can occur.

Where do you find out your pupillary distance?

You can have your PD measured at your local optical store although sometimes they charge a small fee for this if you just walk in off the street without an appointment for your prescription. Often times, your doctor will have it written somewhere on your prescription or it may be written on a past prescription. The good news is that your PD never changes once you are an adult! Once you’ve had it measured for the lenses of your eyeglass frames, the PD always stays the same. It is always best to check with your eye doctor to see if they have your PD written somewhere.

Measuring your pupillary distance on your own

Here is what you need:

• A friend to help with the measurement.
• A PD ruler or a measuring tape that can measure in millimeter (mm)
  
  Please note: measuring your PD by yourself is not recommended because it is not always as accurate as having a trained optician take your measurement.
  
  Start by taking off your eyeglasses – for an accurate reading, not wearing eyeglasses is best. It is also best for both you and your friend to be sitting about 45cm apart. Have your friend sit in front of you with the ruler – one eye of theirs should be closed. Have your friend place the ruler on your forehead and line up the side with the zero directly with the middle of your pupil on your left eye. Slowly follow the ruler and line it up with the middle of the pupil on your right eye. Make sure your head does not move during this process or the results will not be accurate! Be sure to take note of the measurement. You should also try this at least three times to ensure accuracy.
  
  For most people, the PD value generally ranges between 57mm and 65mm – the average PD is 63. If you measured your PD and it falls at 50 or below or at above 70- you may have measured wrong.
  
  While it really is not recommended to measure your own PD – it is a cost-effective alternative. Your best option is to call your optician or a previous optician who may have recorded the number.