The most common cause of out-of-focus eyes is strabismus, where one eye sees horizontally and the other eye sees obliquely, and the two eyes see at different angles. Usually, strabismus causes both eyes to look at something while only one eye is looking at the object, and the other eye is skewed out or causes double vision, most often with exotropia or internal strabismus. In adults, surgical correction may be required in most cases. If the strabismus is still not relieved after 3-6 months of glasses, surgery may be needed to resolve the strabismus.