BACKGROUND: Several studies reported on various aspects of visual function at
term age and in the first months after birth but less has been reported in
preterm infants before they reach termequivalent age.
AIMS: To assess the suitability of a battery of tests of visual function for use
in infants born at <33weeks gestation (GA) and assessed before 34weeks
post-menstrual age (PMA); to evaluate the distribution of the findings according
to GA, and to compare the data with those previously published on preterm infants
assessed at 35weeks PMA.
STUDY DESIGN: Cross-sectional study.
SUBJECTS: Sixty-four preterm infants with a GA <33weeks were studied.
OUTCOME MEASURES: We used a battery of visual function tests previously validated
at 35 and 40weeks PMA in low-risk preterm infants. All the infants in this
current study underwent the same assessment before 34weeks PMA.
RESULTS: Before 31weeks PMA most infants could not be reliably assessed because
of clinical instability, whilst after 31weeks PMA most infants could be assessed
and they showed progressive maturation in their responses with PMA. Some items
(spontaneous ocular motility, horizontal tracking, tracking a coloured stimulus,
and ocular fixation) showed similar results at 32-33weeks PMA to those found in
low-risk preterm at 35weeks PMA. Ocular movements to a target and arc tracking
were the items with the most immature responses.
CONCLUSIONS: Our results provide further evidence that a structured assessment of
visual function can be used in clinical routine and for research purposes in
infants as young as 31weeks PMA.