Vertical and horizontal smooth pursuit eye movements in children with developmental coordination disorder

AimOur aim was to study horizontal and vertical smooth pursuit eye movements in children with developmental coordination disorder (DCD). MethodHorizontal and vertical smooth pursuit eye movements of 91 children were studied using electro-oculography: 27 children with DCD (23 males, four females), according to the DSM-IV-TR criteria, and 64 comparison children (26 males, 38 females). All children were 7 to 12years old (mean 9y, SD 1.5y). Among the group of children with DCD, eight had received intervention. Intervention exercised static and dynamic fixation, saccades, visual strategies, visuospatial abilities, and eye-hand coordination. A smooth pursuit gain index was calculated and statistical comparisons were made between the two groups of children. ResultsHorizontal pursuit gain was similar in both populations, but vertical pursuit gain was significantly impaired (p<0.001, after adjusting for age as covariate), i.e. more saccadic in children with DCD (18-99%; n=27, mean 51.6%, median 48.5%, SD 23.2%) than in comparison participants (35-97%; n=63, mean 66.4%, median 65.0%, SD 15.4%). Among the DCD group, the vertical pursuit index was also significantly higher (p=0.009) in the intervention subgroup (29-99%; n=8, mean 69.4%, median 75.5%, SD 28.7%) than in the non-intervention subgroup (18-74%; n=19, mean 44.1%, median 42.5%, SD 15.9%). InterpretationThese results suggest a delay in the maturation of the pursuit system in children with DCD. What this paper adds First assessment of horizontal and vertical pursuit in children with DCD. Horizontal pursuit gains are typical in 7- to 12-year-old children with DCD. Vertical pursuit gains are significantly impaired in 7- to 12-year-old children with DCD.