What is inter-pupillary distance (PD) and why is it so important for fabricating glasses?
Inter-pupillary distance (PD) is the distance from the center of the pupil in one eye to the center of the pupil in the other eye. A PD measurement ensures that the center of the lenses line up with the center of your pupil. Before your prescription lenses are cut into the shape of your frame, the pupillary distance needs to be measured. This measurement is then used so that the optical center of each lens can be lined up with your pupils in order to give optimal visual clarity.
