Which type is more likely to show diplopia when the objective angle is the same: PAC 1 or NRC?

Which type is more likely to show diplopia when the objective angle is the same: PAC 1 or NRC?

• A. PAC 1
• B. NRC
• C. HAC
• D. UHAC

Answer: (A)

Diplopia shows up when two retinal images fall outside what the brain can fuse together. That fusion tolerance is tied to Panum’s area and to how well the visual system can align and suppress images as needed. When the objective angle—the real misalignment—is the same, the type that has the smallest or weakest fusion/suppression capacity is the one most likely to show diplopia. PAC 1 tends to have the least robust fusion reserves among the options, so the disparity is more likely to fall outside its fusion range and produce diplopia. The other types—NRC, HAC, and UHAC—generally have stronger or more adaptable fusion/suppression mechanisms, making diplopia less likely at the same misalignment.

Diplopia shows up when two retinal images fall outside what the brain can fuse together. That fusion tolerance is tied to Panum’s area and to how well the visual system can align and suppress images as needed. When the objective angle—the real misalignment—is the same, the type that has the smallest or weakest fusion/suppression capacity is the one most likely to show diplopia.

PAC 1 tends to have the least robust fusion reserves among the options, so the disparity is more likely to fall outside its fusion range and produce diplopia. The other types—NRC, HAC, and UHAC—generally have stronger or more adaptable fusion/suppression mechanisms, making diplopia less likely at the same misalignment.