When your eyes do not look at the same thing.
Strabismus occurs when both eyes do not point at the same object at the same time. One eye may turn inward or outward, or it may alternate between the two eyes. Strabismus is usually something you are born with but it can be acquired due to trauma. In cases where strabismus has been present before the age of six, stereopsis or “3D vision” is usually absent because the brain did not learn how to look at an object with both eyes at the same time. Surgery is sometimes indicated to help re-align the deviating eye, as well as vision therapy to encourage both eyes to work together.