Comparison of Four Dissociated Phoria Tests: Reliability & Correlation with Symptom Survey Scores

Previous studies have found the modified Thorington test and the Howell phoria card test to be more repeatable than the von Graefe test. Another potential way to assess the value of a test could be to correlate test results with the level of symptoms. Near dissociated phorias were measured with the modified Thorington, Howell phoria card, and von Graefe procedures with 50 subjects between the ages of 18 and 35. The von Graefe test was performed with two different targets, thus making a total of four different phoria tests. All testing was performed using a phoropter. Test findings were correlated with symptom scores from a questionnaire. The means on the four tests ranged from 2.7Δexo to 3.7Δ exo. Correlations of phoria findings with symptom scores were not statistically significant for any of the four tests in subjects with exophoria. In a small number of subjects with esophoria, significant correlations were found between phoria and symptom scores for the modified Thorington test and the Howell phoria card test but not with the von Graefe test. The modified Thorington test and the Howell phoria card test were more repeatable than the von Graefe test. Goss DA, Reynolds JL, Todd RE. Comparison of four dissociated phoria tests: Reliability and correlation with symptom survey scores. J Behav Optom 2010;4:99-104.