Which term describes the prism effect that occurs in only one eye?

• A. Total prismatic effect
• B. Vertical prismatic imbalance
• C. Binocular prism illusion
• D. Prismatic central shift

Answer: (A)

The main idea is that prism power applied to just one eye shifts that eye’s image entirely while the other eye remains unshifted. When the full prism effect appears in a single eye, we call it the total prismatic effect. This distinguishes it from situations where prisms are present in both eyes or where the disparity is described as an imbalance between the eyes.

Vertical prismatic imbalance refers to unequal vertical prism between the eyes, which creates vertical disparity but isn’t about the effect being confined to one eye. The other options aren’t standard terms for this unilateral phenomenon, since they don’t specifically describe having the full prism effect in just one eye.