BACKGROUND The Mallett Unit is a clinical test designed to detect the fixation disparity that is most likely to occur in the presence of a decompensated heterophoria. It measures the associated phoria, which is the "aligning prism" needed to nullify the subjective disparity. The technique has gained widespread acceptance within professions such as optometry, for investigating suspected cases of...

Introduction: In the evaluation of binocular function, the heterophoria is an essential measure. Historically, the relationship of the near phoric measure to the far phoria has been a critical finding in the diagnosis of convergence and divergence anomalies. There are a number of ways that the phorias can be measured. It is noted in the literature that different types of phoria measures are sta...

Numerous physiologic functions of the binocular neuromuscular mechanism have been measured for years with various kinds of testing equipment. Relatively few studies have been made to determine to what extent these various testing devices measure the same or different characteristics. This study was designed to investigate the relationships between lateral heterophoria, prism vergence, and the n...

T'HE fact that the consumption of a sufficient quantity of alcohol will cause diplopia, even in subjects who normally show no heterophoria, is well known. Until recently, the author, in common with many others, thought that this was due to a toxic exotropia, such as is seen in the early stages of anaesthesia. Powell (1938) and Colson (1940) have shown that the effect of alcohol on lateral heter...

Purpose: The aims of this study were to compare fusional vergence measurements between orthophoria, esophoria and exophoria, and to determine the strength of correlations between fusional convergence and divergence and angle of deviation. Methods and materials: A cross-sectional study was performed in children with best-corrected visual acuity of 0.0 LogMAR in either eye, compensated heterophor...