Inferior oblique inclusion after lateral rectus surgery.

A retrospective and prospective study evaluated the clinical characteristics of patients with inadvertent incorporation of the inferior oblique muscle to the lateral rectus muscle after lateral rectus surgery. Nineteen cases were included in the study (12 retrospectively in the preceding 18 months and 7 during the prospective 5-month period). Thirteen cases with the inferior oblique inclusion occurred after a lateral rectus resection and 6 occurred after a lateral rectus recession. Most patients demonstrated a vertical deviation in the affected eye preoperatively. Nine had hypotropia and 8 had hypertropia. Deficient elevation in adduction in all patients was found on motility testing. After reoperation, despite freeing the inferior oblique from the lateral rectus, most patients had a persistent vertical deviation. Inadvertent inferior oblique inclusion can be avoided by inspecting the under surface of the lateral rectus and freeing any inferior oblique attachment before reattaching the lateral rectus to the globe during either resection or recession.