The Developmental Eye Movement (DEM) test is commonly used as a clinical visual-verbal ocular motor assessment tool. However, while the DEM test ratio has been reported to correlate with horizontal saccadic eye movements, there have been 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, reading performance, symptomatology and visual processing speed, to assess the validity of the DEM test in clinical practice.
One hundred fifty-eight 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. All subjects completed a symptomatology survey. Reading performance and visual processing data was collected for 77 and 75 children, respectively.
One hundred twenty-nine of the 158 subjects (81.65%) passed the DEM test. There was no significant correlation between any component of DEM test performance and quantitative eye movement parameters (gain, latency, asymptotic peak velocity, and number of corrective saccades) or symptomatology. There were significant correlations between DEM test outcome and reading performance, and with visual processing speed.
DEM test performance does not correlate with saccadic eye movement skills or symptomatology. However, it is related to reading performance and visual processing speed. This study suggests that although DEM test times may not correlate directly with eye movement parameters, they do correlate with aspects of reading performance and thus may serve a diagnostic role in clinical practice.
§OD, PhD, FAAO
Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Victoria, Australia.
Presented in part at the Association for Research in Vision and Ophthalmology (ARVO) meeting, Fort Lauderdale, FL, April–May 2008 (Ayton LN, Abel LA, Fricke TR, McBrien NA. Does the Developmental Eye Movement (DEM) test actually measure eye movements? Validation of a clinical saccade test. Invest Ophthalmol Vis Sci 2008;49:E-abstract 1810.
Received September 18, 2008; accepted January 26, 2009.