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William V Good, Vincent Bhutani, Chuan Hou, Terri Slagel, Ronald Wong, Kathleen Lewis, Charles Ahlfors, Anthony M Norcia; Visual Acuity is Reduced at One Year in Infants with Neonatal Physiological Jaundice. Invest. Ophthalmol. Vis. Sci. 2014;55(13):842.
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The spectrum of bilirubin-induced neurologic dysfunction (BIND) in neonates is unknown, as is its relationship to bilirubin levels. Infants who have hemolytic disease, disordered bilirubin binding to albumin and/or are preterm infants, are at the greatest risk for BIND. To determine whether alterations in visual cortical function may occur in full-term, non-hemolyzing jaundiced infants, we measured sweep visual evoked potentials (sVEP) at 6 and again at 12 mos of age.
90 full-term infants were recruited at birth from the well child nursery. None had any clinical evidence for hemolysis. Bilirubin measures were determined by measurements of transcutaneous bilirubin (TcB), total plasma bilirubin (TB), and “free” or unbound bilirubin levels. At 6 and 12 mos of age, grating and vernier acuity and contrast sensitivity were measured by a masked observer using the sweep sVEP technique. Correlations between the various measures of bilirubin and visual thresholds were determined for the 6 mos visit and compared to measurements taken at the 12 mos visit. None of the infants had known pathologic reasons for jaundice. Neonatal history was tracked prospectively for predischarge bilirubin, use of phototherapy, exposure to anesthesia (none), heart disease (excluded), and thyroid dysfunction.
Total bilirubin levels ranged from 0.5-21.6 mg/dL (Median 7.9 mg/dL). Contrast sensitivity (p<0.05 at 6 and 12 mos) and vernier acuity (p<0.05 for 6 and 12 months) were significantly related to bilirubin levels. Grating acuity was not affected by bilirubin levels.
Even in a narrow range of newborn jaundice, a reduction in visual sensitivity occurs, persists to 12 mos of age, and correlates with the level of bilirubin in the newborn period for contrast-sensitivity and vernier acuity measures. Since these two visual processing measures likely represent different cortical mechanisms, the effect of jaundice may be widespread in the visual cortex. Longer-term follow-up and measures for a wider range of neonatal bilirubin measures will help determine the clinical significance of these findings.
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