Guides
Pupillary Distance (PD)
What PD means, single vs dual PD, distance vs near PD, and measurement basics.
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Pupillary Distance
Learn what PD means, explore single vs dual PD, and practice educational measurement concepts for glasses fitting.
Prescription Decoder
Paste or enter OD/OS sphere, cylinder, axis, ADD, prism, and PD to get plain-English educational explanations.
Frame Size
Decode eye size, bridge, and temple measurements such as 52□18 140 and learn how frame fit works.
Guides
What PD means, single vs dual PD, distance vs near PD, and measurement basics.
PD on a Glasses Prescription
Pupillary distance helps center lenses. Learn how PD appears with prescriptions and orders—and why DIY PD can fail for progressives.
Single PD vs Dual PD
Single (binocular) PD is one total number; dual (monocular) PDs split right and left. Learn when each matters for lens centration.
How to Measure PD (Educational)
Professional measurement with a pupillometer or calibrated digital system is preferred, especially for progressives and higher powers. Home methods are rough educational exercises.
Average Pupillary Distance
Average PD charts are statistical summaries, not your face. Learn why averages mislead ordering and when professional measurement matters.
Near PD vs Distance PD
Distance PD and near PD differ because fixation distance changes geometry. Learn why progressives and near work make the distinction educationally important.