Your pupillary distance — or PD — is the distance between the centres of your two pupils. We need this measurement to position the optical centre of each lens exactly in front of your eye.
At Olivia Balm, our opticians always check your PD before manufacture. Here are 4 simple ways to send it to us — pick whichever suits you best.
Solution 1 — On your prescription
The measurement may already be written on your prescription, under one of these labels: PD, IPD, Ec, EOD and/or EOG. Just take a photo of it and send it to us. If it isn't there, ask your eye doctor to note it down at your next examination.
EOD = right-eye distance, EOG = left-eye distance (monocular values, measured from the bridge of the nose). PD or Ec = total distance between both pupils. Either format works for us.
Solution 2 — With a bank card or loyalty card
The idea in one sentence: every bank card in the world has exactly the same width, 85.6 mm. If a card appears in the same photo as your eyes, it works as a ruler and we calculate your PD straight from the image.
Because the card's real width is known, a simple cross-multiplication between the two measurements read off the photo gives your PD in millimetres.
What you need
- A card in standard bank-card format: bank card, loyalty card, driving licence or insurance card — all of them are 85.6 mm wide. A business card or a hotel key card will not do: those sizes vary.
- A phone. A selfie works perfectly well: extend your arm as far as it will go and trigger the shot with the self-timer or the volume button.
Step by step
01 — Place the card on your forehead
Flat against the skin, just above your eyebrows, lying down lengthwise — the long edge horizontal, like a small shelf above your eyes. Keep it centred: as much card to the left of your nose as to the right.
02 — Keep as much of the card visible as possible
We need to see its edges.
03 — Push your hair off your forehead and take off your glasses
Nothing should hide your eyes or the card. The card must rest on the skin, not on a lock of hair: otherwise it sits further forward and the scale is distorted.
04 — Look far away, never at the screen
Fix your gaze on something about 5 metres away: a door handle at the end of the room, a tree through the window. That is why you use the self-timer — your eyes stay on the distant object while the photo is taken.
Why this matters most: when you look at something close, your eyes turn inwards and your pupils move closer together. A glance at the screen costs 3 to 4 mm — enough to throw a progressive lens off centre.
05 — Extend your arm as far as it will go
The lens must sit at the same height as your eyes — not above, not below — and the phone must be held straight, not tilted. Your face stays perfectly front-on: no head turn, no chin up or down.
The further away the phone, the more accurate the result: the card sits about 2 cm in front of your pupils, and at close range that offset makes it look bigger than it really is.
The lens sits exactly on the line of your gaze, but your gaze goes past the screen. Shooting from above or below squashes the distance between the eyes.
06 — Check the photo before sending it
Good light, no flash (it creates reflections), sharp image. Your two pupils must be clearly visible, along with the whole card and both of its ends.
07 — Send it to contact@oliviabalm.com
We do the calculation and confirm your PD by email.
The most common mistakes
- ✔️ Card horizontal, flat, properly centred — this is the position we need.
- ✖️ Card upright: the width can no longer be measured.
- ✖️ Gaze on the screen: the pupils move closer together.
- ✖️ Photo at an angle or from above: the distance is squashed.
Not sure? Send us the photo anyway. We check every picture and will simply ask for another one if needed. And if you would rather not do it yourself, you are of course welcome at the boutique: the measurement takes a few seconds.
Solution 3 — With a ruler
Hold a ruler horizontally at eyebrow level. Look straight ahead at an object about 5 metres away. Take a front-on photo and send it to contact@oliviabalm.com. The framing rules from Solution 2 apply here too.
Solution 4 — With a mobile app
Measure your PD automatically from your smartphone, then just follow the instructions in the app:
- iPhone — download PDCheck AR from the App Store.
- Android — download GlassesOn from Google Play.
If you are unsure
Send us your prescription and PD by email, or come into our Lyon store for a free check.