What test is used to measure the direction of a phoria?

What test is used to measure the direction of a phoria?

• A. Cover test
• B. Maddox rod test
• C. Worth 4-dot test
• D. Randot stereo test

Answer: (A)

Phorias are latent eye misalignments that only show up when binocular fusion is disrupted. To determine the direction of a phoria, you need a test that reveals how the eye drifts when fusion is broken. The cover test does this directly: you cover one eye to break fusion and watch the other eye for movement, then uncover and observe how the previously covered eye re-fixes. The direction of that movement tells you whether the eye tends to drift inward or outward when fusion is disrupted—indicating esophoria (inward drift) or exophoria (outward drift). Magnitude can be refined with prism neutralization, but the key for direction is the observable drift during the cover test. Tests like the Maddox rod involve dissociating the eyes to quantify phorias more precisely and depend on subjective responses, while Worth 4-dot and Randot stereo tests assess fusion status or depth perception rather than the directional latent misalignment.

Phorias are latent eye misalignments that only show up when binocular fusion is disrupted. To determine the direction of a phoria, you need a test that reveals how the eye drifts when fusion is broken. The cover test does this directly: you cover one eye to break fusion and watch the other eye for movement, then uncover and observe how the previously covered eye re-fixes. The direction of that movement tells you whether the eye tends to drift inward or outward when fusion is disrupted—indicating esophoria (inward drift) or exophoria (outward drift). Magnitude can be refined with prism neutralization, but the key for direction is the observable drift during the cover test.

Tests like the Maddox rod involve dissociating the eyes to quantify phorias more precisely and depend on subjective responses, while Worth 4-dot and Randot stereo tests assess fusion status or depth perception rather than the directional latent misalignment.