Pupillary distance — or PD — is the distance, in millimetres, between the centre of your two pupils. It is one of the key measurements for producing corrective lenses (both single-vision and progressive) that are truly comfortable.
When correctly centred, your lens gives you sharp, relaxed vision. When poorly centred, it strains your eyes and can cause headaches, dizziness, or double vision — especially with strong prescriptions or progressive lenses.
At Olivia Balm, our opticians always check your PD before manufacture. Here are 4 simple methods to obtain it and share it with us — choose whichever suits you best.
Why is PD essential?
The eye sees with maximum sharpness through the optical centre of the lens. If that centre is not aligned with your pupil, you are looking through an off-axis zone, which creates optical aberrations:
- ✔️ blurred or double vision at certain distances
- ✔️ eye strain after a few hours
- ✔️ discomfort with progressive lenses (reading zone poorly positioned)
- ✔️ headaches by the end of the day
The stronger the prescription, the more centring matters. With progressive lenses, an error of just 1 to 2 mm is enough to compromise overall comfort.
Method 1 — On your prescription
The measurement may already appear on your prescription, under one of the following labels: EP, Ec, EOD and/or EOG. Simply take a photo of it and send it to us. If it is not there, ask your ophthalmologist to include it at your next appointment.
EOD = right-eye distance, EOG = left-eye distance (monocular values, measured from the bridge of the nose). EP or Ec = total distance between both pupils. Either format works for us.
Method 2 — With a bank card
A standard bank card (payment card or loyalty card of the same size) serves as a reference scale for calculating your PD.
- i. Place the card horizontally on your forehead, just above your eyebrows.
- ii. Fix your gaze on an object about 5 metres away, without moving your head.
- iii. Have someone photograph you straight on, in soft lighting.
- iv. Send us the photo at contact@oliviabalm.com: we will calculate your PD using the card as a reference.
Method 3 — With a ruler
- i. Hold a ruler horizontally at eyebrow level.
- ii. Look straight ahead, fixing your gaze on an object about 5 metres away.
- iii. Take a front-facing photo and send it to contact@oliviabalm.com.
Tip: for a self-measurement, close your left eye and align the 0 mark of the ruler with the centre of your right pupil, then close your right eye and read the value opposite your left pupil, without moving the ruler.
Method 4 — With a mobile app
Measure your PD automatically from your smartphone, then follow the app's instructions:
- iPhone — download PDCheck AR from the App Store.
- Android — download GlassesOn from Google Play.
The easiest option: the "Adapt to my prescription" tool
On any frame page, the "Adapt to my prescription" option lets you enter your PD and attach your selfie directly: the photo is sent with your order to our optician, who checks the centring before manufacture. There is nothing for you to calculate.
Reference values
To check whether your measurement seems reasonable, here are the typical ranges:
- Adult woman: 56 to 64 mm (average 60 mm)
- Adult man: 60 to 70 mm (average 64 mm)
- Child aged 5–10: 48 to 56 mm
- Teenager: 54 to 62 mm
If your measurement falls outside these ranges, take it again — it is most likely a minor inaccuracy.
A word from your optician
For single-vision lenses with a moderate prescription, a home measurement accurate to within 1 mm is perfectly adequate. For progressive lenses or strong prescriptions, I prefer to verify it myself — it is free, takes two minutes, and guarantees comfort for several years.
If you are unsure
Send us your prescription and PD by email, or come into our Lyon store for a free check.