But when there is a disruption and the muscles do not work together, some form of strabismus, including exotropia, may occur. Other causes may involve the nerves that transmit information from the brain to the muscles, or the part of the brain that directs eye movements.
de facto segregation-segregation (especially in schools) that happens in fact although not required by law. separatism, segregation-a social system that provides separate facilities for minority groups.
1 An example of something de facto is a rule that people always follow even though it is not an official procedure, a defacto procedure.  An example of something de facto is a person who functions as a parent even though they are not related to the child, a defactor parent.