Little is known about the development of the ocular, or eye, motor system (the parts of the brain that control how the eyes move) in children. Recent technological and methodological advances now enable researchers to investigate the visual system and ocular motor system of infants, but few findings have been reported. This study hypothesizes that quantitative analysis of "at-risk" infants' eye movement systems can detect abnormalities that precede and predict the onset of strabismus, or cross-eye.