Visual alignment from the midline: a declining developmental trend in normal, strabismic, and monocularly enucleated children.

Children, 1.8 to 5.0 years of age, were asked to sight through a tube at targets. There were three groups tested: children with normal binocular vision, children with strabismus, and children with one eye enucleated. The younger normal and strabismic patients placed the tube midway between the two eyes. Surprisingly, the younger enucleated children also placed the tube at the midline. This "Cyclops effect" diminished as the children grew older, with a transition to sighting monocularly by the age of 4 years. The tendency to align with the midline by the younger children, regardless of the degree of their binocular vision, presumably is a natural response to a cyclopean projection center in the midline. As children mature, they learn to meet the demands of monocular preference tasks by aligning objects in front of one eye.