Developmental Eye Movement Test

By Author: Graham Sandras
Total Articles: 4
Comment this article

Ballistic eye movement or saccades position an object on the fovea for high definition vision are vital in reading. The relation between reading dysfunction and saccadic move is well known and is a common area of optometric therapeutic studies. This knowledge along with clinically applicable assessment tools lead to the visual verbal test that can be assumed to depend on quality of ocular motor and rapid automatic naming (RAN) skills. Earlier saccade tests didn’t control the RAN Skills and hence poor test results can be caused by cognitive or verbal delays.
The developmental eye movement (DEM) test was designed to check for RAN ability by incorporating a vertical subtest. Basically three DEM subsets are scored by completion time and errors. Subset A and B comprises of 40 single digit numbers arranged in two vertical columns and need equally spaced small vertical saccades only. Subset C is an array of 16 horizontal rows each with 5 unevenly spaced digits.
The need for horizontal saccade of differing magnitude leads to a presumption that a higher level of ocular motor co ordination would be needed. The DEM test ...
... ratio is given horizontal score divided by vertical score and is designed to differentiate between poor saccadic function and poor RAN ability.
The developmental eye movement test and assumption implicit in the design has lead to its wider scope as an indicator of saccadic programming, oculomotor dysfunction or horizontal saccadic movements. However, there is no empirical evidence till date that DEM test is actually related to eye movements. Therefore this study aims to compare performance on the DEM test with quantitative eye movement recording to access its validity as saccadic assessment tool.
Given the DEM test’s anecdotal support in optometry and education disciplines, three non motor correlates of DEM test performance were also investigate symptomalogy reading ability and visual processing.
It has been seen that ocular motor dysfunction is correlated with symptoms such as skipping and re reading lines from the text and the reading disabilities also correlate with general asthonopic symptoms. A prior study found a relationship between ocular motor dysfunction symptom and the DEM Test, but couldn’t control for confounding factors like attention deficit disorder. Therefore the study is aimed to incorporate a more detailed symptom survey and a larger subject cohort.
Previous studies have shown a link between poor reading and visual verbal saccade tests but these have generally been focused on young and older children. As the DEM test was designed for use in kids in the age group of 6 to 14 years, the present investigation compared reading and DEM test performance in children aged 8 to 11 years.
Visual processing was assessed using a rapid serial visual presentation (RSVP) task commonly used in reading research. This includes representing text sequentially in a fixed location eliminating the need of saccades to successive targets. RSVP provide a measure of reading speed without eye movements, thus giving an indication of visual processing ad verbal skills.
Facing any visual impairments, you should immediately consult a good Toronto Eye Doctor.