Smooth pursuit development in infants.

PURPOSE: We set out to assess the development of pursuit eye movements in normal infants in an objective, longitudinal fashion. We asked whether smooth pursuit (SP) was present under 2 months of age and how the saccade ratio changed with increasing infant age. METHODS: Smooth pursuit was recorded longitudinally from 25 infants aged 1-7 months, using DC electro-oculography, in a clinically practical manner. Four uninstructed adults acted as controls. RESULTS: Smooth pursuit was present under 2 months of age. The gain of SP increased with increasing infant age. However, it had still not reached adult levels by 6 months of age. Latency decreased with increasing infant age. Monocular SP asymmetry was present in the younger infants. CONCLUSIONS: Smooth pursuit is present under 2 months of age, but at 6 months SP has still not reached adult levels. The traditional model of SP development is questionable.