Which type of phoria can be assessed using the Maddox rod?

The Maddox rod is an optical device used specifically to evaluate phoria, which is a latent deviation of the eyes. When assessing phoria using the Maddox rod, a line of light is projected in front of one eye, typically the right eye, while the left eye views a light source. This setup allows the clinician to discern whether the eyes are aligned or if there is a discrepancy in alignment in either the horizontal or vertical direction.

By utilizing this method, both horizontal and vertical phorias can be effectively identified. For horizontal phorias, the patient’s perception of the light line created by the Maddox rod allows the clinician to see if the eyes are converging or diverging from the target. Similarly, for vertical phorias, the orientation of the light line can reveal whether one eye is positioned higher or lower in relation to the other. Therefore, the effectiveness of the Maddox rod in detecting both types of phorias makes the answer valid.