Strabismus occurs when eyes don't line up with each other. Usually, one eye seems to be wandering. You may have heard this referred to as "crossed eyes" or "wall eye." Sometimes it's called "lazy eye" but that is really amblyopia, which we can talk about later. An adult patient might have had this condition since childhood but was never successfully treated, or he or she might have had an illness or injury later in life. People who are born with strabismus will lose binocular vision if they aren't treated, or they will develop double vision.