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Smooth pursuit in infants: maturation and the influence of stimulation
Christina Pieh1, Frank Proudlock, Irene Gottlob
1University Eye Hospital, University of Freiburg, Killianstraße 5, Freiburg 79106, Germany. christina.pieh@uniklinik-freiburg.de
Insights
Infant smooth pursuit eye movements (SPEM) mature rapidly between 2 and 6 months. Stimulus characteristics like size and velocity significantly impact SPEM quality in infants.
Area of Science:
- Developmental neuroscience
- Ophthalmology
- Pediatric vision research
Background:
- Smooth pursuit eye movements (SPEM) are crucial for visual tracking.
- Understanding infant SPEM development is key to identifying visual processing deficits early.
Purpose of the Study:
- To investigate the developmental trajectory of smooth pursuit eye movements in infants.
- To assess how varying stimulus characteristics influence infant SPEM.
Main Methods:
- Infrared photo-oculography used for eye movement recording in 71 infants (1-18 months).
- SPEM elicited using targets of differing sizes (1.2°, 4.7°) and velocities (7.5°/s, 15°/s, 30°/s).
Main Results:
- SPEM maturation peaked between 2-6 months, with significant gain increases across all tested conditions (p<0.0001).
- Higher velocities correlated with shorter pursuit durations and increased saccadic frequency (p<0.0001).
- Larger stimulus size (4.7°) and medium velocity (15°/s) optimized tracking time.
Conclusions:
- Infant SPEM undergoes intensive maturation from 2 to 6 months, approaching adult-like gains by 6 months.
- Stimulus velocity and size critically affect SPEM quality in infants.
- SPEM development remains incomplete by 18 months, highlighting the need to consider stimulus parameters in infant testing.
Purpose:
To investigate the development of smooth pursuit in infants and to assess the influence of different stimulus characteristics.
Methods:
A total of 131 eye movement recordings were obtained from 71 infants between 1 and 18 months of age using infrared photo-oculography. Smooth pursuit eye movements (SPEM) were stimulated using targets of different sizes (1.2° and 4.7° of visual angle) and velocities (7.5°/s, 15°/s and 30°/s).
Results:
Smooth pursuit maturation peaked between 2 and 6 months of age with smooth pursuit gain showing a steep rise for all stimulus velocities and target sizes within this age range (p<0.0001). Higher stimulus velocities were associated with shorter durations of the longest smooth pursuit (p<0.0001) and higher saccadic frequencies (p<0.0001). A larger stimulus size led to an increased saccadic frequency (p=0.035). Tracking time was highest when the larger stimulus of 4.7° of visual angle was applied (p=0.022) and when it moved at a medium stimulus velocity of 15°/s (p=0.0002). The choice between a schematic face and a scrambled face did not influence the quality of the infants' smooth pursuit.
Conclusion:
SPEM show an intensive maturation between 2 and 6 months of life. By 6 months of age SPEM have already reached an almost adult-like gain of 0.8 or higher. Further maturation is slow and still incomplete by the age of 18 months. Stimulus velocity and size have an important impact on the smooth pursuit quality, which should be considered in smooth pursuit testing in infants.
