Abnormal eye movements in hyperkinetic children with learning disability.
Eye movements were studied in 29 school children aged 6--12 years diagnosed as having Hyperactivity (HA) with Learning Disabilities (LD) and compared to an age matched control group of 32 children. The children had to track a moving target on a metronome and a canopy, to maintain eye fixation on a stationary target and to read a standard reading material. Accuracy, nystagmoid, reversal and overshoot movements were observed, as well as head movements and blinks. Persistence and deviations were monitored during fixation; duration, accuracy, number of fixations and reversals were monitored during reading. The tracking accuracy and fixation persistence were significantly inferior in the HA-LD children as compared to the control group in most items. This correlated well with the inferior performance on the reading task. This study supports the hypothesis that children with MBD and learning disabilities have primary defects in the motor control of eye movements which contribute significantly to their reading difficulties.