During a 4 BO prism test, if the left eye moves outward and does not re-fixate, this is indicative of what?

During a 4 BO prism test, if the left eye moves outward and does not re-fixate, this is indicative of what?

• A. Normal finding
• B. Suppression
• C. Diplopia
• D. Fusion preserved

Answer: (B)

Suppression is the idea being tested here. The 4 prism bases-out test creates a divergence demand to see if the brain will still use both eyes. If the left eye drifts outward and fails to re-fixate, it means the brain is not using that eye’s image to maintain a single, fused view. In other words, the left eye is being suppressed to avoid double vision. This pattern indicates suppression rather than normal fusion or diplopia.

Suppression is the idea being tested here. The 4 prism bases-out test creates a divergence demand to see if the brain will still use both eyes. If the left eye drifts outward and fails to re-fixate, it means the brain is not using that eye’s image to maintain a single, fused view. In other words, the left eye is being suppressed to avoid double vision. This pattern indicates suppression rather than normal fusion or diplopia.