Fusional Vergence Amplitudes According to Ages
Dilara Pirhan, MD; Fatma Sumer, MD; Ozgul Altintas, MD, Prof.
Kocaeli University, School of Medicine, Department of Ophthalmology
Introduction: There are rare investigations on relationships between fusional amplitudes by age in healthy binocular people. The aim of this study was to find out the normative values fusional amplitudes according to the ages.|
Methods: Ninety visually normal participants were recruited from ophthalmology practice at Kocaeli University Ophthalmology Department, Turkey. Inclusion criteria included subjects with best corrected visual acuity of 20/20 for distance, absence of any ocular pathology or abnormal ocular motility. None of the subjects had a vertical phoria at either a distance or near viewing distance. The amplitudes of horizontal and vertical are measured in prism diopters.|
Results: A total of 30 children (group 1, range: 9-18 yrs) and 30 young adults (group 2, range:20 -31 yrs) and 30 older adults (group 3, range: 31-40 yrs) participated in the study. The mean fusional convergence was significantly different between groups 1 and 3(p<0.05), and group 2 and 3(p<0.05). Mean fusional divergence was significantly different between groups 1 and 3(p<0.05), and group 2 and 3(p<0.05). There was no significant main-effect of age on the vertical fusional ranges and titmus stereotest(p>0.05).
Discussion: The normal fusional horizontal amplitudes at 6 meters is lower than our study; but patients having esophoria tend to have larger amplitudes; also, in the exophoric patient the amplitudes may be smaller than normal. Also, this difference could be due to the fact that the great range of accommodation observed in children.
Conclusion: It is important to know that is possible to have normal fusional vergence amplitudes and still have dysfunction of vergence system.
References: 1. Rowe FJ. Fusional vergence measures and their significance in clinical assessment. Strabismus. 2010; 18: 48-57.