For NRA/PRA, which statement correctly describes the behavior of the planes of accommodation and vergence?

For NRA/PRA, which statement correctly describes the behavior of the planes of accommodation and vergence?

• A. The plane of accommodation moves and the plane of vergence moves together at the true target location
• B. The plane of accommodation moves while the plane of vergence is fixed at the true target location
• C. The plane of vergence moves while the plane of accommodation remains fixed at the true target location
• D. Neither plane moves

Answer: (B)

In NRA/PRA, you’re testing how the eye’s focusing system (accommodation) responds when the demand changes, while keeping the viewing distance fixed. When plus lenses are added, the eyes can relax their focus, so the plane of accommodation shifts toward less accommodation. The target stays at the same true distance, so the vergence demand needed to fuse that target doesn’t change—meaning the plane of vergence remains fixed at the true target location. The result is that the accommodative response moves while vergence stays put. This is why the correct description is: the plane of accommodation moves while the plane of vergence is fixed at the true target location.

In NRA/PRA, you’re testing how the eye’s focusing system (accommodation) responds when the demand changes, while keeping the viewing distance fixed. When plus lenses are added, the eyes can relax their focus, so the plane of accommodation shifts toward less accommodation. The target stays at the same true distance, so the vergence demand needed to fuse that target doesn’t change—meaning the plane of vergence remains fixed at the true target location. The result is that the accommodative response moves while vergence stays put.

This is why the correct description is: the plane of accommodation moves while the plane of vergence is fixed at the true target location.