Maturation of the vestibulo-ocular reflex in normal infants during the first 2 months of life.

We measured the dynamic properties of the vestibulo-ocular reflex (VOR) in 20 healthy, newborn babies, using sinusoidal and velocity-step rotational stimuli. With sinusoidal stimuli, quick phases of nystagmus were uncommon and there was a large phase lead of eye position over head position that exceeded 20 degrees at frequencies below 0.5 Hz. With velocity-step stimuli, primary nystagmus lasted for a mean duration of 10 seconds and was followed by an early reversal phase of nystagmus. By 2 months of age, primary nystagmus induced by velocity-step stimuli was more prolonged (mean duration, 15 seconds) and the reversal phase occurred later. We postulate that these changes reflect maturation of visual pathways essential in calibrating the VOR so that vision remains clear during head perturbations.