Which tool contains a series of red cylinders used to assess phorias?

The Maddox rod is specifically designed for assessing phorias, which are misalignments of the eyes that become apparent when binocular vision is disrupted. This tool consists of a series of red cylinders that create a visual disparity between the two eyes. When one eye views the red light through the Maddox rod, the red line falls in a different position than the line of sight of the other eye, allowing practitioners to determine the presence and type of phoria.

Using the Maddox rod involves presenting the patient with a point of light while using the rod in front of one eye. This method helps in quantifying the amount of deviation and assists in diagnosing any latent strabismus or phoric conditions.

In contrast, the synoptophore is used for more complex assessments of binocular vision, including fusion and stereopsis, but does not specifically utilize the cylinders for measuring phorias. The cover test evaluates prism cover deviations but is not a direct measurement based on the cylindrical design present in the Maddox rod. The pinhole occluder is primarily used to assess refractive errors and does not evaluate phorias directly.