ABSTRACT

A phoria is a misalignment of the eyes such that the natural resting point is not perfectly aligned. It is only seen when fusion is broken.To compensate for small variations in alignment, the brain has the fusional vergence system in which positive and negative fusional vergence may be used to compensate for a phoria and keep an image single and clear, even if the eyes are not perfectly aligned. The purpose of this study was to compare between the von graefe and Maddox rod horizontal phoria techniques at far and near. The horizontal phoria for far and near was measured on a sample of 72 optometry undergraduate students in the university of Benin (16-30 years) using the von graefe and Maddox rod techniques. The measurements for the test per participants were obtained and afterwards the means were applied in analysis of the result,unpaired t-tests and Bland-Altman analysis were performed to determine the level of agreement. There was no significant difference between phoria measurements using the two techniques at 6 metres (p>0.05). However, there is a statistical difference between the phoria measurements at 40 centimetres (p<0.05). A regression was also carried out to determine if the dependent variable was statistically significant  or not. Among the different methods, the von graefe technique showed better agreement , although the reliability was good for the two technique at distance. It was concluded that the horizontal phoria measurement at near can be best obtained using the von graefe technique. It is recommended that von graefe technique should be used to measure the presence, direction, and intensity of phorias from near and far in clinical settings.

Keywords : phoria, fusion, fusional vergence system, von graefe, Maddox rod.