How to Measure Your PD(Pupillary Distance)?
What Is Pupillary Distance(PD)?
PD is the medical abbreviation for Pupillary Distance. It is the distance that measures from the center of the pupil of one eye to the center of the pupil of the other eye. PD is measured on a millimeter scale.
• An average adult's Pupillary Distance ranges between 54-74 mm.
• The range of Pupillary Distance for kids varies from 43 to 58 mm.
Pupillary Distance of a person is an essential component that tells about where the person is looking through the lens of the eyeglasses, and it must be as exact as possible. It helps the lens maker and provides guidance on where to put the optical center on each lens in order to make customized eyewear.
3 Ways to Write a Pupillary Distance (PD)
1. Binocular PD (Single PD)
Binocular Pupillary Distance or (Single PD) refers to the measurement in a single number. It represents the single number measurement.
For example: "63" or “64” means the pupillary distance or PD between the center of one pupil to the center of the other pupil. It can also show a distance PD measurement or near PD measurement.
2. Monocular PD (DUAL PD)
Monocular Pupillary Distance or (DUAL PD) refers to the measurement in double numbers. It consists of two numbers that show the distance between the center of one eye pupil to the bridge of the nose (nasal bridge).
For example, The distance between the left eye pupil to the nasal bridge or vice versa. Dual Pupillary Distance is generally scripted in the following expression i.e., 32/30. The prior or foremost number always expresses the right eye (OD) measurement, while the latter number represents the left eye (OS).
3. Reading PD
Sometimes Pupillary Distance is also represented in the following notation, i.e., "61/58".
- The first number, 61, shows the distance of PD that can be used whenever a person needs to use any kind of eyewear, i.e., a single vision distance eyeglasses, bifocal specs, or progressive glasses.
- While the second number, 58, expresses the reading Pupillary Distance. It is prescribed to only be used whenever a person is needed to have single-vision reading glasses.
Normally, the reading Pupillary Distance is always meant to be 3mm less than the distance Pupillary Distance. Because whenever a person reads, the eyes will get closer to that object.
If you are using a Monocular or Dual Pupillary Distance to calculate the near PD, then subtract 1.5mm from each of the eye‘s measurements.
For example: If the Dual PD is 33/31mm. Then subtract 1.5mm from both of the numbers i.e., 33-1.5=31.5mm and 31-1.5=29.5mm. So the near PD would express in the following manner 31.5/29.5mm.
How To Measure Your PD at home?
Step No.1- Make Your Position:
First thing first, align yourself and make a position at an arm's length distance from your friend/partner or yourself at approximately 8 inches or 20cm away from a mirror.
Take measurements of your Pupillary Distance 2-3 times to make sure that you get an accurate result.
Step No.2- Start Measuring On One Eye:
After adjusting your position the second step is to close one of your eyes. For example: Close your right eye and then put the scale on your left eye and place 0 mm over the center of your left pupil.
Step No.3- Repeat the Process For The Second Eye:
Now, repeat the above-mentioned process on the right eye. For example: Close your left eye and then note the reading directly over your right pupil. This will show your Total Pupillary Distance PD.
Step No.4- Ensure Your Results:
In the end, you also have to measure the individual distance from both of the pupils to the center of the nose bridge. To make sure that if you have two Pupillary Distances i.e.
Oculus Sinister (OS): This means the left eye
Oculus Dextrus (OD): This means the right eye
A Few Things to Note:
- Measure your PD 3-4 times to ensure it's accurate and consistent.
- Range of Adult PD: 54-74 mm
- Range of Child PD: 43-58 mm