At a recent Expert Colloquium in 1997, Greifswald, Germany, 10 scientists from different fields of research came to some general conclusions about the present state of research in dyslexia.
Problems in oculomotor control have also been considered because dyslexics show an abnormal pattern of the saccadic eye movements during reading. It remains unclear whether the abnormalities are intrinsic to the oculomotor system or a consequence of difficulties in language processing. Saccadic eye movements have been repetitively measured during non-cognitive tasks, however the finding of an increased number of regressions during saccades to sequentially presented light stimuli has remained controversial. Today we know that the voluntary component of saccade control as measured by antisaccade performance differentiates dyslexics from controls, while prosaccade performance does not.
When tested for dynamic vision by the use of the visual tasks provided by FixTrain systematic developmental deficits can be seen in dyslexia.
To overcome the developmental deficits in saccade control a specific training procedure was developped. The children were given a home training (FixTrain) by which they could practice those aspects of their saccade control system, which were out of the limits of age-matched controls. The effects of daily practice on saccade control are specific for the task that were used during the training period.
|The reaction times of saccades to a suddenly presented stimulus (prosaccades) do not systematically differentiate dyslexics from controls with the exception of the youngest group.|
|Comparison of the error rate in an antisaccade gap task clearly differentiates between dyslexics and controls with the exception of the youngest group. Both groups improve with age but the development of dyslexics stays behind that of the controls.|
Dynamic vision as tested during stationary fixation, prosaccade and antisaccade conditions shows systematic differences bewteen dyslexics and controls.
|Training effects on the performance of the antisaccades as evaluated by the percentage of misses, i.e. trials in which even after 2 saccades the subject did not reach the opposite side. The curve of the controls are shown together with the values before and after training.|
|Improvements in the antisaccade domain are counted by the number of improved variables. If one accepts 3 or 4 improved variables as indication for an improvement the total rate of success reaches about 85%.|