General principles in the surgical treatment of paralytic strabismus.

The surgical approach necessary to achieve the largest field of usable single binocular vision in patients with paralytic strabismus is one that has a greater effect in some directions of gaze than in others. Developing the appropriate "incomitant" strabismus surgery can be achieved by improving the ocular rotation of the involved eye(s), creating a matching rotation defect in the "normal" eye, and anticipating that surgery may create a new/different deviation (not present before the surgery) that can be used to surgeons' advantage. The severity of the limitation in ocular rotation will determine the amount and type of strengthening or weakening that will be necessary to the paralytic muscle and its yoke muscle.