Pupillary Distance

How To Measure Your Pupillary Distance
What is Pupillary Distance?
Pupillary distance (PD) is the distance between the centers of your pupils measured in millimeters. The average adult’s PD is between 54 – 74mm; children’s are between 43 – 58mm.
Why Is It Important?
Optical Center
The PD is used by the lens maker to align the “Optical Center” of each lens with your pupil. An inaccurate PD may cause headaches and eye strains.
Measuring Your Own Pupillary Distance
Before we get started, make sure you have the following handy:
1. Millimeter Ruler
2. Mirror
Now, follow these steps to measure your own PD:
Step 1. Stand 8 inches away from the mirror.
Step 2. With your face straight, hold the ruler against your eyebrow.
Step 3. Close your right eye and align the ruler’s zero to the center of your left pupil.
Step 4. While looking straight, close your left eye and open your right eye.
Step 5. Read the millimeter line that lines up with the center of your right pupil. This number is your PD.
Make sure you repeat this atleast 3 or 4 times to make sure that your PD is accurate. You can read the average PD of adults and children at the beginning of the article.
Having a Friend Measure Your Pupillary Distance
If a friend is measuring your PD;
Keep both eyes open and have your friend put the zero of the millimeter ruler over the center of one pupil. Then measure the distance to the center of the other pupil.
Make sure to keep your eyes still and don’t look at the person measuring. You can look above his/her head at something 10 – 20ft away.