What is your pupillary distance?
The pupillary distance (PD) is the distance between the centre of one pupil to the centre of the other pupil. Prescription glasses are made so that the distance between the optical centres of the glasses’ lenses is the same as your PD.
Your PD varies from person to person but once you are an adult, your PD does not change. Therefore, as an adult, if you have had it measured, then it will still be the same, even if your spectacle prescription has changed. Once you know your PD, you do not need to measure it every time you buy prescription glasses.
PD is measured either during the eye test or when prescription glasses are ordered. Obviously we cannot measure your PD over the internet, so it is best to make sure your PD is included in your glasses prescription.
We strongly recommend that you get this from a trained professional before you buy glasses online. However, If you are not able to get your PD from an optician you can try the following method below:-
- Place a millimetre ruler on the bridge of your nose.
- Have somebody stand opposite you, both on the same level.
- Have them measure the distance between the centre of your pupils (the black dots on the middle of your eyes).
You can try this yourself simply by looking in the mirror.
Look straight ahead and mark the centre of your pupils with dots (using a magic marker or felt tip) on the mirror directly. Measure the dots with the ruler afterwards.
If you need your glasses on to do this, you can draw the dots directly onto the front of the lens whilst looking in the mirror. Again, measuring the dots off your glasses with a ruler afterwards.
This measurement generally can be anything between 57mm and 70mm. although the average pupillary distance is 63mm.
When buying cheap glasses online with us, we have an automatic default of 63mm on our order form when entering your prescription. If nothing is entered, this PD measurement will be used.