The developmental eye movement (DEM) test is a clinical test used widely to evaluate ocular motility function (accuracy and speed) in school-age children.
The purpose of this study was to investigate, retrospectively, the change in accuracy over time while performing the DEM horizontal reading task in children.
The charts from children who had performed the DEM test during a routine eye examination in a pediatric optometry service were reviewed. The study included 22 patients (6 to 11 years old, 12 boys, 10 girls) who had a routine eye examination that was precepted by one of the authors (R.C.) during the period of 1995 to 1999. Patients were divided into two categories: 1) those with abnormal DEM test results and 2) a control group consisting of those with normal DEM test results. Chart review was done consecutively within each category. Collected data included patient age, gender, refractive error, and DEM test results. For analysis, the horizontal task of the DEM was divided into two halves (I and II), Part I always preceded part II, and data was sorted as the number of errors per part.
More errors in accuracy occurred in part II than in part I (Wilcoxon signed rank test, p ≤ 0.01) of the horizontal DEM test in the group of subjects with an abnormal DEM test. No differences in the number of errors in parts I and II of the horizontal task of the DEM were found in the control group.
Findings showed that when excessive errors in accuracy occurred, the number of errors increased over time. If the errors were caused by an oculomotor dysfunction found in the DEM, errors should be equally distributed throughout the text. If errors were caused by fatigue, a difference in parts I and II should have occurred in both the test and the control group. These findings suggest that attention may influence accuracy over time in those patients that do poorly on the DEM test.