Your PD or Pupillary Distance measurement is the distance in millimetres between the centre of both your pupils. The PD measurement is essential to ensure your lenses are optically centered which gives maximum optical accuracy and vision correction.
It's quite possible your prescription already includes this, but sometimes it isn't. Even if it is, it may be entered for each eye which means both numbers need to be added together when entering into our online ordering process.
The average PD for adults is around 63mm so this gives you an idea of what the number should be.
How to measure your PD yourself
If your PD is missing from your prescription, it's really easy to measure this accurately yourself. All you need is a friend and a ruler!
1) Stand or sit where you can look at a distinct object 4 or 5 metres away from yourself that is roughly the same level as your eyes. This will help you to keep your eyes steady.
2) Get your friend to hold the ruler to your forehead like this image, with the 0mm line over the very centre of your left eye.
3) Now your friend needs to stand straight in front of you and see what the measurement is over the very centre of your right eye. Write it down.
4) Repeat this process two more times to be quite sure it's correct. Done!
