What does the frame PD measurement represent?

The frame PD measurement represents the distance between the optical centers of the lenses in a pair of eyeglasses. This measurement is essential for ensuring that the lenses are properly aligned with the wearer's eyes for optimal vision.

The correct answer indicates that the frame PD is calculated by adding the "A" measurement, which refers to the width of the lens, to the "DBL" or "distance between lenses," which measures the space between the two lenses. This sum provides a comprehensive measurement of the total distance across the front of the frame, ensuring that the lenses are positioned correctly based on the unique facial structure of the wearer.

Understanding this measurement is vital for eye care professionals when fitting glasses, as a correctly measured frame PD maximizes visual comfort and effectiveness.