You may have obtained your PD or Pupil Distance from your optician or optometrist or it may be noted on your prescription. If not you will need it measuring.
Your Pupil Distance measurement will normally be between between 60 and 65mm though it is not unheard of for a pupil distance to fall within 55 to 70mm.
Measuring your Pupil Distance Is measuring Pupil Distance difficult to do?
We recommend the following method:
- Recruit a willing assistant.
- Face each other, stood or sitting so both parties are at a similar height.
- The subject being measured should look beyond the measurer, maybe over their shoulder, at a distant object, or one at least a few metres away.
- Depending on the eye colour, the easiest way to measure pupil distance will be to measure at the opposite edges of the pupil, or the iris as shown, with a millimetre rule placed against the forehead.
- Measure a few times to make sure you are seeing consistent results.
Send us a pair of your specs
If you aren't confident you have the correct measurement you can send a pair of specs to us, and we can take the pupil distance from those, assuming they have been made accurately which if you find them comfortable to wear should be the case.
Use an image for scale
- Have your phone ready to take a picture.
- Put a credit card or similar against your forehead.
- Take a 'selfie' with the phone at arms length and with your gaze beyond the phone and into the distance.
- Repeat until you have a good result with your face & gaze straight and the card horizontal.
- Open the image in any software that will allow crop and scale/resize.
- Crop out a portion containing just the width of the card and your eyes.
- Credit cards are 85.6mm so resize this image to 85.6mm or 856 pixels.
- Crop again to get your pupils (centre to centre or edge to edge, as shown).
- The new image size will be your pupil distance (divide by 10 if using pixels).
Feel free to send an image to us and we will calculate the pupil distance measurement for you.
Does it matter?
You will read on the net that an average is fine, or it hardly matters etc, so what is the truth regarding the pupil distance, or PD?
Well it depends on the strength of the prescription, a small prescription with the PD slightly off will be no problem at all for most, but a large prescription a considerable way off will cause a certain degree of strain to the muscles which control the direction of gaze.
The eyes default to looking straight ahead, turning requires effort.
Put simply, if the lenses are not centred correctly then the image in front of your pupil is not heading in straight, so to speak, so the eye needs to turn slightly to align it.
You can not damage your eyes with incorrectly centred lenses, but fatigue may be experienced with headaches and possibly double vision in extreme cases. In short the larger the prescription, the more accurate the PD needs to be for comfortable vision.
Varifocal lenses require an accurate PD, they have a channel of clear vision as you move from distance to near and it is important that this is correctly placed.