This is the distance between your pupils and is required for us to make up your glasses perfectly, it is generally between 55 and 75mm. The average measurement for adults is 63mm.

STEP ONE

Find a millimetre ruler & a mirror. Firstly, hold the ruler against your brow

STEP TWO

Close your right eye and align the ruler's 0 to the centre of your left pupil

STEP THREE

Close your left eye, open your right & read the mm line that lines up with the centre of your right pupil

STEP FOUR

Repeat the steps above twice to make sure the number is the same. This is your PD measurement