What Is Pupillary Distance?

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EyeQue Team

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May 22, 2019

Pupillary Distance

Have you ever heard your eye doctor use the term “pupillary distance” during an eye exam? Pupillary distance is also known as a PD or interpupillary distance, and the term refers to the distance between the pupils of your eyes.

Why Does Pupillary Distance Matter?

The Mayo Clinic explains that it is needed to create your eyeglasses. If you look at your eyeglasses, you’ll notice the lenses are not flat—they curve slightly so your prescription will work properly. Your PD measurement helps the eyeglasses manufacturer to align your prescription properly to your eyes.

Eyeglasses lenses
Eyeglasses lenses are curved based on your prescription.


Moreover, the American Optometric Association emphasizes that patients with myopia should be especially mindful of their PD. If eyeglasses are not properly fitted according to the PD measurement, the patient may experience something called “induced prism,” meaning the lenses will not focus light properly to the eyes. This can cause headaches and excessive eye strain. You will notice that your focus is off and that glasses just don’t fit right.

How Does PD Affect My Performance in Sports?

You probably won’t be surprised to learn athletes rely heavily on their vision to be successful in sports, as many sports require accurate depth perception. Studies have shown that changes in “binocular cues” directly impact your depth perception and athletic performance. Examples of binocular cues include tilting your head forward, looking over your shoulder, and your glasses’ or sports goggles’ response to your PD.

Is My PD Normal?

According to the American Academy of Ophthalmology, the average pupillary distance measures between 60 to 62 millimeters. If you have a pupillary distance which is longer than normal, you may have a condition called hypertelorism(also known as hypertelorbitism). Normally, this condition is only corrected for aesthetic reasons.

Where Can I Learn More About Pupillary Distance Measurements?

Baby Boomer Couple Using PDCheck
Measuring your pupillary distance is a snap using EyeQue’s PDCheck!


EyeQue offers PDCheck which is a pair of patented frames that you can use with a pupillary distance app so that you can measure your PD quickly and accurately. Find out more about PDCheck here!

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