Which of the following statements about the Maddox rod is correct?

The Maddox rod is a clinical tool used in optometry to assess the presence and degree of both horizontal and vertical phorias. When using the Maddox rod during testing, the patient typically views a light source while the rod alters the position of the light seen through one eye, allowing the examiner to evaluate the eye's alignment and any deviations that may occur.

One of the key features of the Maddox rod is its flexibility in testing both types of phorias. It is effective at measuring horizontal phorias, such as exophoria and esophoria, as well as vertical phorias like hyperphoria and hypophoria at both near and distance settings. Therefore, the statement that the test cannot be used for horizontal phorias is incorrect, as this is one of the primary applications of the Maddox rod.

The ability of the Maddox rod to measure vertical phorias at both near and distance makes it a versatile tool in optometry, reflecting its comprehensive range of applications in assessing eye alignment and binocular vision. This capability underscores the importance of the correct understanding of the tool in optometric practices.