This is simply the distance between the middle of the pupil in one eye to the middle of the pupil in your other eye. We need this measurement to make sure that your lenses sit correctly.
Ask your optician to note this on your prescription when you have your eye-test. If this hasn't been done though, you can take this measurement yourself by using a ruler that shows millimetres.
* Sit or stand in front of a mirror. * Place the ruler across the top (bridge) of your nose. * Measure the distance between the middle of one pupil and the other.As a guide, an average PD is 63mm so if you have difficulty taking this measurement yourself or do not provide it, we will automatically make up your glasses to this average.