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Smooth pursuit eye movements in children
Michael S Salman1, James A Sharpe, Linda Lillakas
1Section of Pediatric Neurology, Children's Hospital, University of Manitoba, AE 108, Harry Medovy House 820 Sherbrook St., R3A 1R9 Winnipeg, MB, Canada. msalman@hsc.mb.ca
Insights
Children
Area of Science:
- Neuroscience
- Developmental Psychology
- Ophthalmology
Background:
- Smooth pursuit eye movements are crucial for maintaining clear vision of moving objects.
- Limited data exists on smooth pursuit eye movements in pediatric populations.
- Understanding developmental trajectories of eye movements is vital for assessing visual-motor integration.
Purpose of the Study:
- To characterize smooth pursuit eye movements in typically developing children.
- To investigate the effects of target frequency and direction on smooth pursuit performance.
- To examine age-related changes and compare pediatric to adult smooth pursuit capabilities.
Main Methods:
- Utilized infrared eye-tracking technology to record eye movements in 38 children (aged 8-19 years).
- Participants performed horizontal and vertical smooth pursuit tasks with sinusoidal target motion (0.25 Hz and 0.5 Hz).
- Analyzed smooth pursuit gain (eye velocity/target velocity) and phase (time lag).
Main Results:
- Lower smooth pursuit gains were observed in children compared to adult norms.
- Vertical smooth pursuit gains were significantly lower than horizontal gains.
- Higher target frequencies (0.5 Hz) resulted in reduced gains compared to lower frequencies (0.25 Hz).
- Smooth pursuit gains increased with age, approaching adult values by mid-adolescence.
- Phase lag was not significantly influenced by age, but was larger than in adults, suggesting less mature predictive capabilities.
Conclusions:
- Pediatric smooth pursuit eye movements are less accurate than adult's, particularly for vertical and higher-frequency movements.
- Developmental improvements in smooth pursuit are evident through adolescence, with gains approaching adult levels.
- Immature predictive mechanisms in the smooth pursuit system are indicated by larger phase lags in children.
Abstract:
Smooth pursuit eye movements consists of slow eye movements that approximate the velocity of the eyes to that of a small moving target, so that target image is kept at or near the fovea. Little information on smooth pursuit is available in children. We used an infrared eye tracker to record smooth pursuit in 38 typically developing children, aged 8-19 years. Participants followed a visual target moving sinusoidally at +/-10 degrees amplitude, horizontally and vertically at 0.25 or 0.5 Hz. The mean horizontal smooth pursuit gains, the ratio of eye to target velocities, were 0.84 at 0.25 Hz and 0.73 at 0.5 Hz. Mean vertical smooth pursuit gains were 0.68 at 0.25 Hz and 0.45 at 0.5 Hz. Smooth pursuit gains were significantly lower for vertical in comparison to horizontal tracking, and for 0.5 Hz in comparison to 0.25 Hz tracking (P<0.0001). Smooth pursuit gains increased with age (P<0.01, Pearson's correlation tests), with horizontal gains attaining reported adult values by mid adolescence. Vertical gains had large variability among participants. The median phase, the time interval between eye and target velocities, varied between 39 and 86 ms. Phase was not influenced by age. We conclude that smooth pursuit gains are lower in children than gains reported in adults. Vertical pursuit gain is significantly lower than horizontal pursuit gain. Gains improve with age and approach adult values in mid adolescence. Children have larger phases than reported adults values indicating that prediction in the smooth pursuit system is less mature in children.
