What describes the NRA endpoint criterion?

• A. The endpoint is when the patient first notices depth perception.
• B. The endpoint is when either accommodation fails resulting in blur or vergence fails resulting in diplopia.
• C. The endpoint is when the patient is perfectly fused.
• D. The endpoint is after 1 diopter of demand.

Answer: (B)

The main idea is that the NRA endpoint marks the limit of the binocular system’s ability to maintain single, clear vision as relative accommodative/vergence demand increases. You’re testing how far the eyes can relax accommodation (and the corresponding vergence) before fusion or clarity breaks down.

The best description is that the endpoint is reached when accommodation can no longer stay clear (blur) or vergence can no longer stay aligned (diplopia). In other words, you stop the test at the first sign that the system can’t maintain fusion or sharpness, which defines the NRA limit.

Depth perception isn’t the metric used here, and you don’t stop at perfect fusion or at a fixed amount like 1 diopter of demand.