How to measure your Pupillary Distance (PD)
What is Pupillary Distance?
Pupillary distance (PD) measures the distance between the centres of your pupils when you are looking at an object far away.
Most VR devices move the headset lenses to correctly align with your eyes, so a PD measurement is not required.
You only need to provide PD information for specific VR devices when we clearly indicate it is required on the order entry page. If it is required, this measurement is used to determine where you look through the lens and should be as accurate as possible, as it will help your eyes align to the centre of the lens. The average adult’s PD is between 54-74 mm.
What is the most accurate way of measuring my PD?
The most accurate way of measuring your PD would be to contact your optician to get them to measure your PD for you.
Single PD vs Dual PD
SINGLE PD is the pupillary distance between the centre of one pupil to the other, which can be a Distance PD or Near PD. Distance PD can be used to order any type of prescription glasses (including VR Lenses) except reading glasses. Read below to learn how to calculate Near PD for reading glasses.
DUAL PD, or monocular PD, consists of two numbers and is the distance between the centres of each pupil to the bridge of the nose. Dual PD is usually written in the following notation: 32/30. The first number is always the right eye (OD) measurement, and the second number is the left eye (OS).
How do I measure my own PD?
Your prescription may tell you your PD. However if your PD measurement is not available, follow the guide below.
Step-by-step guide on how to measure your PD with the help of a friend:
- Keep both eyes open.
- Look at an object straight ahead, but far away from you (over 3 metres).
- Have your friend put the zero on the millimetre ruler over the centre of one pupil.
- Measure the distance to the centre of the other pupil.
Tips to get an accurate measurement:
• Have them crouch/sit while you stand so they are out of your field of vision.
• Keep your eyes as still as possible.
• Look above his/her head at something approx 10-20 ft. away.
• Do not look at the person measuring!
• Take 2-3 measurements to check the accuracy.
Alternatively there are some online apps and phone apps (e.g. PDCheck AR) that will calculate your PD for you.
How do you calculate Near PD For reading glasses?
VR headsets make you focus on something as if it were far away from you, so you use the method above to calculate the ‘Distance PD’. Reading glasses are different as they require your ‘Near PD’. You can calculate ‘Near PD’ for reading glasses by subtracting 3mm from your Distance PD. For example, if your Distance PD is 63mm, then your Near PD is 60mm.