Diplopia on PRA testing is typically associated with which finding?

Diplopia on PRA testing is typically associated with which finding?

• A. Esophoric and/or High NRV Reserves
• B. Exophoric and/or Low NRV Reserves
• C. High AC/A Ratio
• D. Strong Vergence Ranges

Answer: (B)

Diplopia on PRA testing stems from how the vergence system must respond to increased accommodative demand. When minus lenses are added, the eyes must accommodate more and, in turn, converge more to keep the image single. If the patient lacks enough convergence reserve or baseline alignment is outward, fusion can break as demand rises, leading to diplopia. An exophoric posture means the eyes tend to drift outward at rest, so they rely heavily on convergence to stay fused. If their negative relative vergence reserves are low, there isn’t sufficient capacity to adjust vergence when the accommodation demand increases, so diplopia occurs during PRA. High AC/A ratio would pull the eyes in more with accommodation, which can help maintain fusion under PRA stress rather than cause diplopia. Likewise, strong vergence ranges would typically prevent diplopia because the system can adjust more robustly.

Diplopia on PRA testing stems from how the vergence system must respond to increased accommodative demand. When minus lenses are added, the eyes must accommodate more and, in turn, converge more to keep the image single. If the patient lacks enough convergence reserve or baseline alignment is outward, fusion can break as demand rises, leading to diplopia.

An exophoric posture means the eyes tend to drift outward at rest, so they rely heavily on convergence to stay fused. If their negative relative vergence reserves are low, there isn’t sufficient capacity to adjust vergence when the accommodation demand increases, so diplopia occurs during PRA.

High AC/A ratio would pull the eyes in more with accommodation, which can help maintain fusion under PRA stress rather than cause diplopia. Likewise, strong vergence ranges would typically prevent diplopia because the system can adjust more robustly.