Before revision: Pupillary distance (PD) or interpupillary distance (IPD) is the distance in millimeters between the centers of each pupil.Bogren HG, Franti CE, Wilmarth SS.
After revision: Pupillary distance (PD) , more correctly known as interpupillary distance (IPD) is the distance in millimeters between the centers of each pupil.Bogren HG, Franti CE, Wilmarth SS.