what is the pd measurement glasses
What is Pupillary Distance (PD)? Pupillary distance (PD) is the measurement (in millimeters) of the distance between the pupils of your eyes. Pupillary distance is an important measurement used to determine the proper lens shape and alignment of your prescription correction to your line of vision. Without an accurate PD measurement, correcting vision can be difficult since lenses need to be aligned over the center of your pupil for proper clarity.