If the corneal reflex is displaced temporally in one eye during a Krimsky test, which prism should be added to neutralize the finding?

• A. BI prism
• B. BO prism
• C. None
• D. Both

Answer: (B)

In the Krimsky test, you neutralize a deviation by placing a prism in front of the fixing eye to shift the image of the fixation point until the corneal light reflex in the deviated eye lines up with the center of the pupil. If the corneal reflex is displaced temporally in the deviated eye, that indicates outward turning (exotropia). To counteract this, you use a base-out prism in front of the fixing eye. The base-out prism shifts the perceived position of the fixation so that the deviated eye’s reflex moves toward the center, achieving neutralization. A base-in prism would address inward turning (esotropia) and would not correct the exotropia in this scenario. None or both would not appropriately neutralize the specific temporal displacement.