Diplopia on NRA testing is most consistent with which of the following?

Diplopia on NRA testing is most consistent with which of the following?

• A. High Exophoria
• B. Low PRV Reserves
• C. High Exophoria or Low PRV Reserves
• D. Normal Vergence With Diplopia

Answer: (C)

Diplopia during NRA testing shows that the accommodation-vergence system can’t keep the eyes aligned when accommodation is relaxed. In this test you add plus lenses to relax accommodation, which reduces accommodative convergence. If someone has a high near exophoria, they already rely on strong fusional vergence to stay single; relaxing accommodation lowers the input to convergence and can push their vergence reserves past the point of sustenance, leading to diplopia. Likewise, if positive relative vergence reserves are low, there isn’t enough vergence capacity to compensate for the reduced accommodative convergence, again producing diplopia. So diplopia on NRA is most consistent with either high exophoria or low positive relative vergence reserves.

Diplopia during NRA testing shows that the accommodation-vergence system can’t keep the eyes aligned when accommodation is relaxed. In this test you add plus lenses to relax accommodation, which reduces accommodative convergence. If someone has a high near exophoria, they already rely on strong fusional vergence to stay single; relaxing accommodation lowers the input to convergence and can push their vergence reserves past the point of sustenance, leading to diplopia. Likewise, if positive relative vergence reserves are low, there isn’t enough vergence capacity to compensate for the reduced accommodative convergence, again producing diplopia. So diplopia on NRA is most consistent with either high exophoria or low positive relative vergence reserves.