Cover/Uncover Test
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- * Instruct the patient to stare straight ahead at a distant point.
- Cover one of the patient’s eyes with a fogged lens to break the patient’s binocular fixation. If you use your thumb (instead of a fogged lens) for this step, you risk obstructing your view of the patient’s covered eye and risk missing its deviation.
- Allow the patient to recover binocular fixation by removing the fogged lens and then test the patient’s other eye.
- Interpretation:
- If the patient’s eyes remain still throughout this cover/uncover assessment, they are aligned in the setting of both binocular and monocular vision, which, as mentioned, is rare (again, alignment of the eyes with monocular vision is called orthophoria).
- If covering an eye causes it to move, a latent misalignment exists, called a heterophoria, which is common.