What is DBC commonly used to describe in lens fitting?

The distance between lens centers, commonly referred to as DBC (Distance Between Centers), is a critical measurement in lens fitting. This distance ensures proper alignment of the optical centers of the lenses with the wearer's pupils. Accurate DBC measurement is essential for minimizing optical distortions and maximizing the visual clarity of the glasses. When the optical centers of the lenses are aligned with the pupils, it allows for the most comfortable and effective visual experience, particularly for prescriptions that involve astigmatism or higher order corrections.

In contrast, the distance from the bridge's center to the pupil pertains more to fitting and positioning of the glasses rather than the lens specifications. The overall frame width refers to the outer dimensions of the frame, which while important, does not provide information about lens placement. The diameter of the lens blank is related to the raw material size used for manufacturing the lens, but does not address how the lenses will interact with the wearer's vision effectively. Therefore, DBC is indeed essential for achieving optimal lens performance in eyewear fitting.