Normative Values for the Fusional Amplitudes and the Prevalence of Heterophoria in Adults (Khatam-Al-Anbia Eye Hospital - 2009)

Purpose: To determine the fusional amplitudes and the frequency of hetrophoria, in our patients Methods: In this cross sectional study, 111 adults with mean age of 25.6 years were included. All participants had best corrected visual acuity (BCVA) better than 20 /25, more than 60 sec of arc stereopsis and had no heterotropia or other significant eye disorders. Fusional amplitudes were measured at far (6 meters) and near (40 centimeters) by rotary prism and hetrophoria was evaluated by Maddox wing. Results: The total frequency of hetrophoria was 57.7%, and exophoria, esophoria, hyperphoria and cyclophoria were 51.4%, 0.9%, 3.6% and 9.9% respectively. The mean of convergence fusional amplitudes for far and near were 11 prism diopters (PD) and 16 PD and for divergence fusional amplitudes were 7 PD and 14 PD respectively. There were correlations between convergence and divergence fusional amplitudes at far and near. Conclusion: The amount of exophoria had not affected the fusional reserves and the presence of hetrophoria was not related to the visual complaints like asthenopia and transient diplopia.