What Is your Pupillary Distance (PD)?
When buying eyeglasses online, most online vendors will require you to provide your pupillary distance (PD). So, what is the PD, and why is it important, you ask.
The pupillary distance is the distance between the centers of each pupil of your eyes. This measurement informs the optician or the lab technician where to place the optical center of every lens. The optical centers are determined where you look through the lens of your eyewear. The PD measurement should be as accurate as possible. Otherwise, you will experience discomfort wearing your new glasses. Incorrect PD measurement might cause headaches and eyestrains.
Adult PD measurements range from 54-74 mm, while those of kids range from 54-74mm.
How to get your PD
There are two ways you can get your PD. The most recommended way is to visit an eye doctor and measure it during the eye examination.
However, if you did not get your PD in your last eye exam, the second method of obtaining it would measure yourself.
How to Measure Your Pupillary Distance (PD)
Measuring your PD is an easy process. All you need is a ruler and a well-lit mirror. To do it, you can follow the following steps:
- Stand 20 cm away from the mirror and look straight ahead.
- Rest the ruler against the bridge of your nose.
- Close your right eye
- Align the ruler's zero to the center of your left pupil
- Close your left eye and now open your right eye
- Check the millimeter line that aligns with the center of your right pupil. The number you will read represents your PD.
- Repeat the process 3-5 times to get an accurate measurement.
Enlisting the help of a friend might be a better method of obtaining your PD. You might get a more accurate measurement when you request your friend to help. Here are the steps that you can follow:
- Stand at an arm's length from your friend (about 70 cm).
- Make sure your eyes are as stable. Look straight ahead (preferably 20 feet away). Your friend should not block your vision, and you should not look at the person measuring your PD.
- Your friend should rest the ruler against the bridge of your nose.
- Have your friend measure the distance between your pupils' centers (the black dots in the middle of your eyes).
The final method you can use to measure your PD is using your current pair of glasses. You will need a felt pen for this method of PD measurement. These are the steps to get your PD:
- Put on your glasses
- Focus on an object that is 20 feet away
- Mark over the object on your left lens
- Mark over the object on your right lens. Make sure that the two dots overlap into one dot when you look at the item that is 20 feet away
- Remove your eyeglasses
- Measure the distance between the dots that you just made
Single PD vs. Dual PD
Single PD is the distance between the centers of each pupil of your eyes. On the other hand, Dual PD has two sets of numbers. These are the distances from the centers of each pupil to the nose's bridge. The first number is the distance between the pupil's centers of the right eye (OD) measurement, while the second set of numbers is the left eye (OS) measurement.