Eye movements in children with delayed reading skills

Abstract

Purpose: Vision can be considered the primary sensory input for development and learning, and any condition that impairs vision, including eye movement anomalies, may reduce performance in learning and recreational environments. The purpose of this study is to evaluate differences in oculomotor behaviour between children who are good/average readers and children with delayed reading skills.

Methods: Binocular eye movement recordings were obtained from 163 children (4-11 years) using a Tobii TX300 eye tracker. A 2° customised animated stimulus moving horizontally and vertically at 6°/s and 12°/s was used to study smooth pursuit. A 2° cartoon character was presented horizontally from -20° to +20° in steps of 5° to study saccades. Velocity and position gains, the number of saccades throughout the smooth pursuit, and the saccadic main sequence were obtained for each participant. The children who had delayed reading skills (n=43) were unmasked after data collection was completed. Means and standard deviations were calculated for children with and without delayed reading skills in each age group. Confidence intervals for the parameters measured were obtained from the good/average readers. Contingency tables were produced showing the proportion of children with and without delayed reading skills with eye movement parameters outside the established confidence intervals.

Results: Paired t-tests showed no significant differences in the means of any eye movement parameter studied between good/average readers and those with delayed reading skills for any age group (p>0.05). In contrast, the eye movement parameters of children with delayed readings skills were more frequently outside the confidence intervals for their age (smooth pursuit: 23.2%; saccades: 34.9%) than was the case for good/average readers (8.3% and 18.3%, respectively). Chi-square tests revealed an association between delayed reading and parameters for horizontal smooth pursuit (x²=6.55; p=0.01) and saccades (x²=4.94, p=0.02) that were outside the confidence intervals.

Conclusions: Children with delayed reading skills have a two-fold increased risk of having their eye movement properties outside the confidence intervals for their age. Hence, there is evidence to support an association between delayed reading and eye movements, suggesting that some of these children may have significantly different eye movements or their eye movements have not developed at the same rate as typical children.