Given frame measurements A=48, B=46, E.D.=54, and DBL=18, which seg height is not acceptable for double D's?

In the context of double D (D.D.) glasses, which are characterized by their unique shape and fitting requirements, the segment height is crucial for ensuring proper visual alignment and comfort for the wearer. To understand why a segment height of 25 mm is not acceptable, we need to consider the specific frame measurements provided.

The key measurements include A (the width of the frame), B (the depth of the frame), E.D. (the effective diameter), and DBL (the distance between the lenses). These measurements collectively impact the dimensions of the fit, especially for segment heights in bifocal or progressive lenses. A common rule of thumb in dispensing is that the segment height should generally be lower than the depth of the frame to ensure functionality and aesthetic appearance.

Given that the depth of the frame (B) is 46 mm, when looking for acceptable segment heights, it's essential that the measured height does not exceed this depth significantly. A segment height of 25 mm occupies a substantial portion of the frame's depth, leaving only a limited amount of space above the segment for fitting. In practice, the segment heights should be well-distributed to avoid crowding the frame, and heights closer to 22 mm might be more reasonable but still warrant careful consideration