State of awakeness during visual fixation in preterm infants.
To demonstrate the presence of discriminable awake states in preterm infants, facial behaviors and visual fixation to a single patterned stimulus were recorded. Five healthy preterm infants born at a mean of 29 weeks' gestation were followed from 30 to 35 weeks' postmenstrual age. Behaviors (eye openness, movements, mouthing, and vocalizations) were recorded simultaneously with visual fixation measured by the corneal reflection technique. Test time was determined by the duration of time the infant remained awake before crying or closing eyes. The presence of both quiet awakeness and drowsiness was demonstrated. Younger infants spent more time in drowsiness, whereas older infants had more quiet awakeness. Visual pattern fixation was observed as early as 30 weeks. Fixation time increased with increasing postmenstrual age. More fixation was observed during quiet awakeness than during drowsiness.
D005133:Eye Movements; D005143:Eyelids / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D012894:Sleep Stages / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*