Strabismus, or crossed eyes, is the term for when a person cannot align both eyes on an object at the same time. Strabismus can be constant or intermittent (i.e. due to stress or illness). The condition occurs in about 5% of children. It may manifest at first as double vision. Eventually, the brain begins to ignore, or suppress, information from the weaker eye. If left untreated, strabismus can lead to visual impairment, loss of binocular vision, and blindness in the weaker eye. Therefore early treatment is best, preferably before the age of six, although older patients can be helped as well.