Strabismus is the intermittent or constant misalignment of an eye so that its line of vision is not pointed at the same object as the other eye. Strabismus is caused by an imbalance in the extraocular muscles which control the positioning of the eyes. Strabismus is normal in newborns but should resolve by the time the baby is 6 months old. In older children with strabismus, the brain may learn to ignore the input from one eye, and this may lead to amblyopia, a potentially permanent decrease in vision in that eye if not corrected.