Comparison of Cover Test and Maddox Rod Phorometric Techniques at Far and Near Distances

In this study we Compared Cover test and Maddox rod phorometric tests. These tests can be used for the evaluation of heterophoria and different binocular vision syndromes. “Tests evaluation” is considered in this Comparative study. Cover test is standard test for evaluation of ocular motility. Normal volunteer students of rehabilitation faculty took part in this study. They evaluated according to their any ocular or systemic problems that may be affecting their heterophoria. They were 123 females and 79 males’ subjects, at 18 to 23 years age range. Two tests were done at far (6m) and near (40 cm) randomly crossed over method. The subjects did not suffer any diseases which may affect their ocular motility. Statistical analysis of data was done by Statgraphics TM package. The results revealed, there is tendency of exophoria in Cover test (-0.3) and an esophoria for Maddox rod (+0.3) at far distance. There is a significant difference in Cover test and Maddox rod for far distance (P<0.001). At near distance, two tests show similar results (-3 exophoria). Two eyes dissociation and accommodation activation are basically different in the tests. The significant difference that has been reported at far distance, originated from different dissociation. At near different dissociation and accommodation activation, neutralizing each other. Maddox rod test for far distance more esophoria and less exophoria than Cover test. Different interaction of dissociations and accommodation activation in these tests may result as an unpredictable outcome. For the accommodative and vergence anomalies, the Maddox rod may not be useful at near distance.