Medial Transposition of the Lateral Rectus Muscle in the Experimentally Induced Medial Rectus Paralysis

Yu, Young Suk; Choe, Dong Kiu

Abstract

When the oculomotor nerve is completely paralyzed. the affected eye shows severe outward displacement and poor cosmetic appearance. The results of many surgical procedures for oculomotor palsy have been generally unsatisfactory. We tried a new surgical approach experimentally. in which the disinserted lateral rectus muscle was used as an adductor by medial transposition of the muscle. Five adult cats underwent tenectomy of the medial rectus muscle of the eyes to induce iatrogenic medIal rectus paralysis. The segment of the medial rectus was removed as far back as possible to prevent reattachment. Then, right lateral rectus muscle was disinserted and passed beneath the superior rectus muscle and resutured to the sclera 4mm superoposterior to the medial rectus insertion site. After tenectomy of bilateral medial rectus. large exotropia of an average of 47.6 delta (42.0 delta - 55.5 delta) was induced. The medial transposition of the right lateral rectus produced an average 36.6 delta (24.8 delta - 45.8 delta) of correction of exotropia. A satisfactory cosmetic result was achieved by this procedure. It may be a good alternative procedure in difficult cases of oculomotor nerve palsy with severe outward deviation.