Which condition is expected to show improvement in NPC with plus lenses?

• A. Convergence insufficiency
• B. Pseudo-convergence insufficiency
• C. Divergence insufficiency
• D. Accommodative esotropia

Answer: (B)

The key idea is how accommodation and convergence interact through the accommodative convergence mechanism. Plus lenses reduce the amount of accommodation needed for a near target, which in turn reduces the accommodative convergence drive. When near-vision symptoms mimic convergence insufficiency but the NPC actually improves once accommodation is relaxed with plus lenses, the situation is likely pseudo-convergence insufficiency. In this condition, the apparent vergence problem isn’t a true vergence deficit, so relaxing accommodation reveals a normal or improved NPC.

In contrast, a true convergence insufficiency is a genuine vergence weakness; lowering accommodation with plus lenses doesn’t fix the underlying vergence limitation, so the NPC remains limited. Divergence insufficiency affects the ability to diverge rather than converge, so plus lenses don’t specifically restore NPC. Accommodative esotropia involves misalignment driven by accommodation, and while plus lenses can reduce the accommodative drive, the hallmark improvement isn’t the near-point convergence finding you’d expect in pseudo-convergence insufficiency.