The Effect of Physical Exercise on Dissociated Phorias

Purpose. Binocular vision issues, which can be due to abnormal phorias, cause a variety of visual symptoms including diplopia, decreased depth perception, and asthenopia. The goal of our research was to determine if physical exercise can change an individual’s phoria. Currently, there are no studies to link exercise with a change in a phoria. Methods. Eighteen subjects walked on a treadmill for one mile at a walking pace of 3.5 miles per hour with a 1% incline. The subjects’ phorias were measured with the modified Thorington test at distance and near before walking, immediately after exercise, and twenty minutes post exercise. Phorias measured prior to exercise and post exercise were analyzed using the two-tailed paired ttest. Phorias measured prior to exercise and twenty minutes post exercise were analyzed using a separate two-tailed paired t-test. Results. A significant esophoric shift in the distance phoria measurement was found immediately after walking, but returned to near baseline readings twenty minutes post exercise. Near phoria measurements showed a significant esophoric shift both immediately after walking and continued to become more esophoric twenty minutes post exercise. Conclusion. Physical exercise does cause an esophoric shift in an individual's phoria immediately after exercise at both distance and near. After resting, an individual’s distance phoria will likely shift back towards their original baseline phoria. At near, an individual’s phoria will continue towards an esophoria deviation. However, due to our small sample size, further research using a larger sample size is recommended.