# Pupillary distance: which measurements should you record?

Binocular PD is the distance between the pupils. Monocular PD records each eye relative to the nasal reference used during measurement.

## In practice

Record right and left eyes separately in millimetres and identify distance or near measurement. Do not automatically halve binocular PD: a face may be asymmetric.

## Example record

Right 31 mm and left 33 mm total 64 mm when measured from the same reference. Keeping only 64 mm loses the per-eye information. This is a fictional example.

## Verification

Keep posture, target and reference consistent. Verify measurements with the adjusted frame and the laboratory fitting procedure. A photograph alone does not establish measurement accuracy.

## References

- [Laramy-K / OpticianWorks — ABO Study Guide](https://opticianworks.com/wp-content/uploads/2024/01/Laramy-K-OpticianWorks-Ultimate-ABO-Study-Guide-v6.23.pdf)

## Related topics

- [Optical centration: from measurement to fitting](https://lensas.com.br/en/knowledge/optical-centration/)
- [How to calculate horizontal decentration](https://lensas.com.br/en/knowledge/horizontal-decentration/)

Educational content · Fictional examples · Automated technical review, no claimed clinical validation.

Canonical: https://lensas.com.br/en/knowledge/pupillary-distance/
Version: 2026-09-15.1