Orbital complications secondary to endoscopic sinus surgery. Eight cases of significant orbital complications associated with endoscopic sinus surgery are described. The anatomic problems generally fall into four categories: nasolacrimal sac or duct injury, extraocular muscle injury, intraorbital hemorrhage/emphysema, or optic nerve injury. The successful management of each complication depends on a thorough knowledge of the anatomy and pathophysiology of the orbital injury. Return to normal function of the traumatized orbital structures after medical and/or surgical intervention is anticipated. However, direct optic nerve injury with immediate visual field and/or acuity deficit is usually irreversible. 