Abstract
Purpose: :
Preterm infants are at high risk for visual and neural developmental problems. However, development of visual cortical function in preterm infants with no retinal or neurological morbidity has not been well defined. In order to determine whether premature birth itself alters visual cortical function in infancy, we assessed swept Visual Evoked Potential (sVEP) responses longitudinally at 5-7 months, 8-10 months and 11-13 months corrected age by comparing preterm infants to age-matched term infants.
Methods: :
Fifty-eight Very Low Birth Weight (VLBW) infants with no retinal, neurological morbidities or ROP-Plus disease and fifty term infants were enrolled. However, after excluded missing visits, there were seventeen VLBW infants and eighteen term infants who completed the study. Recruited VLBW infants were between 24 and 33 weeks of gestational age and weighed less than 1500 grams at birth. Spatial frequency, contrast and vernier sVEP responses were measured for all three visits. Acuity thresholds and suprathreshold response amplitudes were compared between groups.
Results: :
Preterm infants with VLBW showed reduced amplitudes for grating, contrast and vernier measures, compared with term infants. These neurophysiological changes persisted to 11-13 months of corrected age.
Conclusions: :
Preterm infants had measurable and significant changes in cortical responsiveness up to 11-13 months corrected age compared with age-matched controls. These results suggest that premature birth in the absence of identifiable retinal or neurological abnormalities has a detrimental effect on visual sensitivity during infancy, and that the changes are unchanged over 3 successive examinations. Longer term follow up studies should be done in premature infants to learn whether these effects endure.
Keywords: visual development: infancy and childhood • electrophysiology: clinical • visual cortex