associated phoria

The amount of prism required to eliminate a fixation disparity. It represents the prism power needed to compensate for the misalignment of the visual axes under binocular viewing conditions. Associated phoria is typically measured using a fixation disparity test, such as the Mallett unit or the Bernell lantern with a polarized fixation disparity target. The associated phoria helps guide the prescription of prismatic corrections for symptomatic patients with binocular vision disorders.