1 Print the ruler
Print this page at 100% sizeusing the NO SCALING setting
3 Look in a mirror or find a friend
Stand 8 in. (20 cm.) away from a mirror or a friend. Place & hold the PD ruler against your brow. Keep your face straight.
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4 Close your eyes
Close your right eye and align the ruler’s zero to the center of your left pupil.
5 Reday. set. measure.
Try to not move your head or the ruler. First open your right eye and close your left eye. Look straight ahead and read the millimeter line that matches up with the center of your right pupil. This number represents your PD in millimeters.