Convergence insufficiency primarily has difficulty with PFV or NFV?

Convergence insufficiency primarily has difficulty with PFV or NFV?

• A. PFV
• B. NFV
• C. Both
• D. Neither

Answer: (A)

Convergence insufficiency shows up as difficulty bringing the eyes together to fuse near targets, so the key measurement affected is positive fusional vergence. PFV reflects how much convergence the eyes can achieve beyond the demand of a near target; in CI, this convergence reserve is reduced, especially at near, so the patient cannot sustain adequate inward turning to maintain single vision. That’s why near exophoria is common and symptoms like eyestrain or headaches occur with near tasks. Negative fusional vergence, which measures the ability to diverge the eyes, is not the primary problem in CI and is usually normal or less affected, which is why the primary deficit is in PFV.

Convergence insufficiency shows up as difficulty bringing the eyes together to fuse near targets, so the key measurement affected is positive fusional vergence. PFV reflects how much convergence the eyes can achieve beyond the demand of a near target; in CI, this convergence reserve is reduced, especially at near, so the patient cannot sustain adequate inward turning to maintain single vision. That’s why near exophoria is common and symptoms like eyestrain or headaches occur with near tasks. Negative fusional vergence, which measures the ability to diverge the eyes, is not the primary problem in CI and is usually normal or less affected, which is why the primary deficit is in PFV.