Near point of convergence (NPC) refers to the:

Near point of convergence (NPC) refers to the:

• A. The closest point of single binocular vision; break around 6–10 cm.
• B. The far point where single vision is lost.
• C. The distance at which fusion stops for dichoptic viewing.
• D. The point at which vergence is maximum.

Answer: (A)

Near point of convergence is the closest distance at which both eyes can maintain a single, fused image as an object is moved toward the face. As the target gets closer, the eyes must converge more; when the convergence demand exceeds what the vergence system can provide, the images can no longer fuse and diplopia occurs. That distance, typically around 6–10 cm in adults, is the NPC. This concept is about the limit of the binocular fusion system under increasing convergence demand, not about the far point of vision, fusion limits under a dichoptic setup, or the point of maximum vergence.

Near point of convergence is the closest distance at which both eyes can maintain a single, fused image as an object is moved toward the face. As the target gets closer, the eyes must converge more; when the convergence demand exceeds what the vergence system can provide, the images can no longer fuse and diplopia occurs. That distance, typically around 6–10 cm in adults, is the NPC. This concept is about the limit of the binocular fusion system under increasing convergence demand, not about the far point of vision, fusion limits under a dichoptic setup, or the point of maximum vergence.