The Standard of Vergence Eye Movements in Children with Reading Difficulties

Jan E. Wulff, MAppSc(Orth) DOBA MOAA

Children with reading difficulties frequently present with reduced Vergence ability. This study investigated the visual status of 94 children aged 8 to 10 years old, 53 who read at the appropriate level for their age or better and 41 who read at least 6 months behind the level for their age.
The children were assessed using the GAP reading test, followed by a full orthoptic assessment that included visual acuity, cover test for near and 6 metres, ocular movements, accommodation, stereopsis, reference eye, hand and eye dominance as well as eight measures of Vergence and the results were compared between the two groups using a two factor analysis of variance.
The results showed a small but significant reduction in fusional divergence in the reading difficulty group measured with the prism bar for near (p=.005) and distance (p=.024) and fusional convergence for distance (p=.030). The results also showed a significant difference for hand dominance (p=.038) with more left handed subjects in the reading difficulty groups. There were no significant differences between the two groups on all other measures. Prism fusion range measurements for near and distance should be included in the routine orthoptic evaluation of children with reading difficulties.