If you want to order a blended bifocal, you should ______ the seg height.

• A. Raise by 1 mm
• B. Lower
• C. Maintain
• D. Raise by 0.5 mm

Answer: (A)

Seg height is where the boundary between distance and near vision sits on the lens. For a blended bifocal, you want the transition to begin higher so the reading area lines up with the wearer's downward gaze and the gradual blend from distance to near sits in the correct place. Raising the seg height by about 1 mm places more of the lower lens into near vision and helps the blend feel natural and usable in daily viewing. Lowering would move the near portion downward and reduce the effective reading area; keeping it the same may not position the blend correctly for typical head and eye posture; raising only 0.5 mm might not provide enough shift in many cases.