Which of the following is NOT a way to lower the bifocal seg height of spectacles?

• A. Increase pantoscopic tilt
• B. Spread the pads
• C. Stretch the bridge
• D. Increase the vertex distance

Answer: (D)

Seg height is the vertical position of the near segment on the lens as it lines up with the wearer’s pupil. To lower that segment, you adjust how the frame sits on the face so the eye lines up with a lower portion of the lens. Increasing pantoscopic tilt rotates the frame so the bottom edge moves closer to the eye, effectively lowering the near segment. Spreading the pads changes how the frame rests on the nose, which can drop the whole frame and shift the segment downward. Stretching the bridge widens how the frame sits across the nose, similarly lowering the frame and the bifocal edge relative to the pupil.

Increasing vertex distance, on the other hand, moves the lens farther from the eye without changing the vertical position of the frame on the face. While it alters optical properties (like effective power and field of view), it doesn’t reposition the bifocal edge on the lens, so it does not lower the seg height.