Learning Hub
Understanding PD, one topic at a time.
Short guides for people buying glasses. You do not need to be an expert. Each guide shows its clinical review status.
Featured · Practical guide
Why isn't my PD on my prescription?
No PD on your prescription? Ask if it was measured and is in your record. Find out if you need a new measurement.
- 02(in review)
PD basics
What is PD, and why does an online glasses order ask for it?
Learn what pupillary distance (PD) means. See why order forms ask for it and what to do if it is missing.
Draft · Clinical review pending
- 03
Reading a report
Single vs dual PD: one number or two?
Learn how one PD number differs from a number for each eye. Two numbers do not always mean right and left.
Clinically reviewed
- 04
Reading a report
Near vs distance PD: what do the labels mean?
Learn what distance and near labels mean. You cannot swap them. Find out what to ask about progressive lenses.
Clinically reviewed
- 05(in review)
Ordering online
When an online glasses order asks for PD
Check the PD fields on an order form. Compare them with the words on your own report.
Draft · Clinical review pending
- 06(in review)
Measuring PD
Can I measure my own PD?
See when home PD measurement may be an option, when to choose a professional, and why stronger lenses need more precise measurements.
Educational draft · Clinical review pending
- 07(in review)
Measuring PD
How to measure your PD
Follow the five-step mirror or helper method with a millimeter ruler. Learn the limits of each method and which labels to keep with the result.
Educational draft · Clinical review pending
Have a PD report? Understand My PD Numbers explains the labels.