Una.C N 01

What is PD value?

Pupillary Distance (PD) is the distance between the centers of your pupils in millimeters, used to align the optical center of prescription lenses with your eyes for clear vision. Accurate PD ensures comfort and prevents eye strain. Typical adult PD falls between 54–74 mm.

Single PD (Binocular PD)

1. Stand in front of a mirror and hold a ruler horizontally across your brow.
2. Align the center of your right pupil with the 0 mm mark on the ruler.
3. Without moving your head or ruler, look straight ahead into the mirror.
4. Read the millimeter measurement on the ruler that lines up directly with the center of your left pupil.
5. Record this single total number (typically 54–74 mm).

Dual PD (Monocular PD)

1. Stand in front of a mirror and hold a ruler horizontally across the bridge of your nose.
2. Align the 0 mm mark precisely with the center line of your nose bridge.
3. Look straight ahead into the mirror.
4. Right Eye (Right PD): Read the millimeter measurement that lines up with the center of your right pupil.
5. Left Eye (Left PD): Read the millimeter measurement that lines up with the center of your left pupil.
6. Record the two separate numbers (e.g., 31 mm / 32 mm).