Maturation of eye movements in premature infants is associated with white matter injury measured by MRI and MRSI.

Abstract

Abstract: : Purpose: Visual impairment is a common cause of morbidity in premature infants and is commonly associated with white matter injury. Visual development is closely correlated with the development of both conjugate gaze and fixation behavior in the newborn. Utilizing magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) techniques, we determined whether white matter injury and levels of N–acetylaspartate, a marker of cerebral integrity, were related to the development and maturation of eye movements in preterm infants. Methods: Twenty–seven consecutive preterm newborns (post–conceptional age <36 weeks) without retinopathy of prematurity, syndromic malformation, congenital infection, or large parenchymal hemmorhage or infarction, had eye movement examinations, MRI, and MRSI tests. Eye movement examinations, employing a grading system to judge fixation behavior and conjugate eye movments, were performed within 24 hours of MR imaging. Two examiners, each blinded to the MRSI and MRI findings, graded the eye movements independently. Results: Among infants of equal post–conceptional age, both fixation behavior and conjugate gaze were significantly worse in those with moderate white matter injury (P=0.03 and P=0.04, respectively) as compared to those without white matter injury. Increasing fixation scores were associated with higher levels of N–acetylaspartate in the thalamus (P=0.03), optic radiations (P=0.006), and primary visual (striate) cortex (P=0.04). Likewise, higher grades of conjugate eye movements were associated with increased levels of N–acetylaspartate in the basal ganglia (P=0.001), thalamus (P<0.0001), optic radiations (P=0.001), and primary visual (striate) cortex (P=0.006). Conclusions: The physiological maturation of eye movements, with regard to both fixation behavior and conjugate gaze, is closely correlated to the integrity of subcortical and cortical visual centers as measured by MRI and MRSI neuroimaging techniques.

Keywords: eye movements: conjugate • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • visual development: infancy and childhood