What if PD Is Off by 1mm? When the PD is wrong by a millimeter the outcome for the wearer will be very different depending on the lens power in the glasses. A wrong pupillary distance is measured in millimeters. This distance multiplied with the lens power equals the deviation a wrong PD produces.
How off can your pupillary distance be?
Measurement ranges Average pupillary distance for an adult is between 54-68mm, with acceptable measurement deviations generally falling in between 48mm and 73mm. The range for children is approximately 41-55mm.