Evaluation of binocular summation ratio before and after vision training in patients with intermittent exotropia
Mohammad Yaser Kiarudi1 *, Masoud Rostami2 , Mehdi Sharifi2
- Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
- Department of Optometry, Mashhad University of Medical Sciences, Mashhad, Iran.
Abstract: to investigate binocular summation ratio before and after vision training in intermittent exotropia (IXT) under different light conditions and evaluate its relationship with control of deviation
Methods: Twenty patients aged 7 to 28 years with IXT were included. Patients based on the control of their deviation were assigned to poor, fair, and good control groups. Sensory ocular dominancy was assessed using the worth four-dot test. Evaluation of contrast sensitivity with CSV1000-HGT chart was evaluated in 4 spatial frequencies (3, 6, 12, 18 Cycle/degree) monocularly and binocularly at a distance of 2.5 meter in photopic and mesopic light conditions with and without glare. Binocular summation ratio (BSR) for each patient before and after the process of vision training was calculated.
Results: The ratio of mesopic binocular summation in conditions without glare showed a significant increase in spatial frequencies of 3, 6, and 18 Cycle/degrees after vision training. In the frequency of 12 cycle/degrees, the increase in the ratio of binocular summation was not significant. The mesopic binocular summation ratio increased significantly in all frequencies of 3, 6, 12, and 18 in glare conditions. The ratio of photopic binocular summation in the condition without glare increased in frequencies 3, 6, and 18, however, this increase was not significant. In the frequency of 12 cycle/degree, the ratio of binocular summation increased significantly after vision training. The ratio of photopic binocular summation in the condition with glare increased at frequencies 3, 12, and 18, although its value was not statistically significant, and only at frequency 6, a significant increase in the ratio of binocular summation was observed. The degree of control of deviation after vision training improved significantly, and the amount of far and near deviation decreased significantly after vision training.
Conclusion: Binocular summation ratio and deviation control score in IXT patients revealed significant improvement after vision training, showing this treatment method may be effective in the management of IXT patients.
