During FCC for a pre-presbyope, you initially add six diopters of plus. After the vertical lines are darker, you apply four diopters of minus, and the horizontal and vertical lines are equally dark. What is recorded for the FCC result?

During FCC for a pre-presbyope, you initially add six diopters of plus. After the vertical lines are darker, you apply four diopters of minus, and the horizontal and vertical lines are equally dark. What is recorded for the FCC result?

• A. +0.50 D
• B. +0.00 D
• C. +1.00 D
• D. -0.50 D

Answer: (A)

FCC tests balance accommodation between the vertical and horizontal meridians by using a cross cylinder approach: you fog with plus to relax accommodation, then remove plus with minus until both meridians appear equally clear (or dark, depending on the chart). The value recorded is the dioptric power at that balance point. In this scenario, starting with six diopters of plus makes the vertical meridian clearer. After applying four diopters of minus, the two meridians are equally dark, indicating the balance point has been reached. The FCC result is the dioptric power corresponding to that balance point, which, with the given steps and rounding convention used in this test context, is recorded as +0.50 D. The other options would reflect balance points at different levels of plus or minus, which doesn’t match the observed equal darkness at the balance point.

FCC tests balance accommodation between the vertical and horizontal meridians by using a cross cylinder approach: you fog with plus to relax accommodation, then remove plus with minus until both meridians appear equally clear (or dark, depending on the chart). The value recorded is the dioptric power at that balance point.

In this scenario, starting with six diopters of plus makes the vertical meridian clearer. After applying four diopters of minus, the two meridians are equally dark, indicating the balance point has been reached. The FCC result is the dioptric power corresponding to that balance point, which, with the given steps and rounding convention used in this test context, is recorded as +0.50 D. The other options would reflect balance points at different levels of plus or minus, which doesn’t match the observed equal darkness at the balance point.