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L. N. Ayton, L. A. Abel, T. R. Fricke, N. A. McBrien; Does the Developmental Eye Movement (DEM) Test Actually Measure Eye Movements? Validation of a Clinical Saccade Test. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1810. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The Developmental Eye Movement (DEM) test is a widely used clinical saccadic eye movement assessment tool, which involves reading vertical and horizontal sequences of numbers. However, to date there are no published comparative studies of the DEM test and objective eye movement measures. The aim of this study was to compare DEM test performance with explicit quantification of saccadic eye movements, to assess the validity of the DEM test as an ocular motor assessment tool.
Forty one children aged 8 to 11 years completed the DEM test and a battery of eye movement tasks, recorded by a Microguide 1000 infrared eye tracker. The tasks were: 1) reflexive saccades, 2) a computer version of the DEM test and 3) an arrow direction task, designed to exclude numerical processing. All children completed a vision screening and symptom survey (the Convergence Insufficiency Symptom Survey- CISS) prior to testing.
A pilot study of 24 children showed highly significant correlations between the paper DEM test and the computer version developed for this study, both in test duration and number of errors. The main study included 41 subjects, of which 31 (75.6%) passed the DEM test (according to published normative values). There was no significant correlation between paper DEM test performance and the following saccade parameters: gain, latency, asymptotic peak velocity and number of corrective saccades. Ten children were diagnosed with a non-strabismic disorder of binocular vision, of whom 8 were already undergoing treatment (low plus lenses and/ or vision therapy). There was no correlation between binocular vision status and DEM test performance. No significant relationship between symptomatology (as quantified by the CISS) and the DEM test was found.
Results demonstrate no significant relationship between saccadic latency, gain, peak velocity or accuracy with performance on the DEM test. Although the DEM test has anecdotal support for its use in clinical practice, the present study raises questions about the validity of the test as a saccadic eye movement assessment tool. Further investigation will focus on other possible saccadic and perceptual correlations.
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