What condition does a Maddox rod help to assess?

The Maddox rod is an essential tool used in the assessment of phorias, which are latent deviations of the eyes that may not be apparent when both eyes are open but can become evident when one eye is covered. By using a Maddox rod, a practitioner can measure the extent of the deviation by presenting a line of light to one eye while the other eye sees a point of light. This setup makes it easier to evaluate the alignment of the eyes and to determine whether a person has a phoria such as exophoria, esophoria, or cyclophoria.

The Maddox rod allows the clinician to quantify the degree of misalignment and helps to identify how the eyes work together under different conditions. It plays a crucial role in diagnosing and managing conditions that involve eye muscle imbalance, which is a primary concern in eye care.

In contrast, myopia, hyperopia, and astigmatism are refractive errors that relate to the eye's ability to focus light correctly. While these conditions may influence visual acuity, they do not specifically pertain to the measurement of eye alignment or deviations, hence they are not applicable in the context of the Maddox rod assessment.