What is a typical use of the Maddox rod in strabismus testing?

• A. Large vertical deviations.
• B. Small vertical deviations.
• C. Small horizontal deviations.
• D. Suppression testing.

Answer: (B)

The Maddox rod is used to dissociate the eyes so you can read off small misalignments as a line seen by one eye and a point by the other. When you place the rod before one eye and a bright light in front of both, that eye perceives a line while the fellow eye sees a point. The perceived relative position—whether the line is above, below, or aligned with the point—provides a direct, sensitive readout of vertical misalignment. By adding prisms to neutralize that offset, you can quantify a small vertical deviation in prism diopters. It’s particularly effective for detecting and measuring small vertical deviations; large vertical deviations often require different tests or methods, and horizontal deviations are typically assessed with other orientations or tests. Suppression testing is a separate assessment and not the primary use of the Maddox rod.