Purpose: To protect the public from the risk of harm that is present when the public purchases eyewear, including from online sources.
An interpupillary distance (PD) measurement is a measurement of the distance between the centers of your two eyes. This measurement is used to properly align the center of your eyeglass lenses with the center of your eyes. If the centers of your eyeglass lenses are not aligned properly, then you may experience eyestrain, headaches, distorted vision, double vision, blurred vision and/or an inability to wear your eyeglasses.
A PD measurement is part of the dispensing service, not part of the eye examination. Other dispensing services include selection of an appropriate frame, recommendation of an appropriate lens type (and coatings), adjustment of the frame, PD measurement and proper placement of the bifocal or multifocal (if appropriate). It is the responsibility of the person/company providing the dispensing service to accurately measure your PD.