THE EFFECT OF TORSIONAL MUSCLE DYSFUNCTION AND SURGERY ON EYE POSITION UNDER GENERAL-ANESTHESIA

Under general anesthesia, normal eyes exhibit 2.0-degrees to 2.5-degre es of extorsion. To investigate the effect of torsional muscle dysfunc tion and surgery on eye position under general anesthesia, we measured the torsional change before and after torsional muscle surgery in 26 eyes of 18 patients with clinical torsional muscle dysfunction. Under general anesthesia, compared with normals, eyes with preoperative into rter overaction or extorter underaction demonstrated a significant int orsional change (P < .01). However, eyes with intorter underaction or extorter overaction did not demonstrate a significant extorsional chan ge. Postoperatively, while patients remained under general anesthesia, intorter weakening procedures produced measurable extorsion while int orter strengthening procedures and extorter weakening procedures produ ced measurable intorsion. Superior oblique tenotomy produced a greater net torsional change than inferior oblique weakening surgery (P < .01 ). Under general anesthesia, eyes with preoperative torsional muscle d ysfunction exhibit torsion in the direction consistent with the dysfun ction. After surgery on the torsional muscles, a measurable torsional effect can be demonstrated while the patient is still under general an esthesia.