What Is Pupillary Distance (PD) and Why Does It Matter?
What Is Pupillary Distance (PD) and Why Does It Matter?
If you're ordering prescription glasses online, one of the most important measurements you'll need is your Pupillary Distance, commonly known as PD.
Many people receive their glasses prescription but are unsure what PD means or why it's required. In this guide, we'll explain everything you need to know.
What Is Pupillary Distance?
Pupillary Distance (PD) is the distance, measured in millimetres, between the centres of your pupils.
This measurement ensures that the optical centre of your lenses lines up perfectly with your eyes. When the lenses are correctly aligned, you experience the clearest and most comfortable vision possible.
Why Is PD Important?
Even if your prescription is accurate, incorrect PD measurements can cause problems such as:
Blurred vision
Eye strain
Headaches
Difficulty focusing
Reduced comfort when wearing glasses
For this reason, PD is one of the most important measurements when ordering glasses online.
What Is a Typical PD?
Adult PD measurements usually range between 54mm and 74mm.
Children typically have smaller measurements.
Every person is different, which is why your PD should always be measured individually.
Single PD vs Dual PD
You may come across two different types of PD measurements:
Single PD
A single measurement from the centre of one pupil to the centre of the other.
Example:
PD = 64mm
Dual PD
A separate measurement from the centre of your nose to each pupil.
Example:
Right PD = 32mm
Left PD = 32mm
Dual PD can provide slightly greater accuracy, particularly for stronger prescriptions.
How to Measure Your PD at Home
If your optician has not provided your PD, you can often measure it yourself.
Method 1: Use a Ruler
Stand in front of a mirror.
Hold a millimetre ruler against your brow.
Align the zero mark with the centre of one pupil.
Look straight ahead.
Measure the distance to the centre of the other pupil.
Repeat several times and calculate the average measurement.
Method 2: Ask Someone to Help
Having another person measure your PD can often improve accuracy.
Can I Order Glasses Without My PD?
Most online glasses retailers require a PD measurement to manufacture lenses correctly.
Without it, your glasses may not provide the best visual experience.
Does PD Change Over Time?
For most adults, PD remains stable once facial growth is complete.
Children's PD measurements can change as they grow and should be checked periodically.
Ordering Glasses Online with Confidence
At SpexNation, we make ordering prescription glasses online simple. Once you have your prescription and PD measurement, you can choose your frame, select your lenses, and complete your order in just a few steps.
Final Thoughts
Pupillary Distance may seem like a small measurement, but it plays a major role in the comfort and performance of your glasses.
Taking a few extra minutes to obtain an accurate PD can help ensure your new glasses provide the clearest possible vision from the moment they arrive.