Comparison of Amplitudes of Fusional Vergence in Patients ‎with Asthenopic and Asymptomatic Near Exophoria

In this study, fusional vergence amplitudes were compared in patients with symptomatic and asymptomatic near exophoria.
This cross-sectional study included 102 patients with near exophoria and asthenopia and 86 with asymptomatic near exophoria, all of whom were aged 15-35 years and had best corrected far visual acuity better than 20/25. Far and near fusional vergence amplitudes were evaluated in all the patients. The subjects were not hyperopic.
We observed significant between group differences in near negative fusional vergence (NFV) break (15.91±4.90 PD vs. 14.73±4.60 PD, p=0.013), near NFV recovery (12.33±3.90 PD vs. 13.79±3.97PD, P=0.009), and far NFV recovery (5.58±3.50 PD vs. 4.50±2.70 PD, P=0.019). Other vergence amplitudes did not differ significantly.
Although it was previously assumed that asthenopia is related to convergence insufficiency (CI), it seems that asthenopia in patients with near exophoria may be related to increased amplitudes of negative vergence.