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

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

Answer: (A)

Positioning the near portion correctly with a round segment requires compensating for the curved edge. The arc causes the near zone to sit slightly lower in the wearer's line of sight, so you raise the seg height to place the reading area where the eye naturally looks when looking through the near portion. Raising by 1 mm is the standard adjustment to account for this geometry. Lowering or maintaining the height would misplace the reading area, and a smaller raise like 0.5 mm isn’t enough to compensate for the round shape.