If the desired frame is bigger than the frame you have on display, what should you do to adjust the seg height on the new frame?

• A. Compare the A's to each other or B's to each other and divide the difference by 2. Then add this amount to the seg height
• B. Compare A to B and adjust proportionally
• C. Subtract half the difference from seg height
• D. Do not adjust seg height

Answer: (A)

When the new frame is larger, you need to move the bifocal segment up by half the amount that the frame’s overall size has increased. To figure this out, compare the two frames in the same dimension—either the A measurements (lens width) or the B measurements (lens height)—and take the difference. Divide that difference by two, then add that value to the seg height. This places the segment higher by half the extra height, keeping the segment’s position visually aligned with the pupil in the bigger frame. Moving the seg height in the opposite direction or not adjusting at all would misplace the segment, and a proportional adjustment isn’t the standard method here since the goal is a specific upward shift equal to half the size increase.