Treatment of Exotropia Caused by Lost Medial Rectus Muscle

ABSTRACT

PURPOSE: We report three patients with large angle exotropia had lost medial rectus muscle (MR) and who attained good alignment postoperatively. METHODS: Patient 1 was a 51-year-old female with a history of strabismus surgery done at 10 years of age. Exotropia of 80 prism diopter (PD) gradually developed with limitation of adduction in the right eye. Patient 2 was a 52-year-old male with fixed exotropia of 95 PD in his left eye, which became blind after a severe contusion injury. The third patient was a 46-year-old male who had MR of the right eye cut during endoscopic sinus surgery. Severe limitation of adduction followed with exotropia of 50 PD. We could not find MR in any of the three patients and noted severe adhesion between eyeball and Tenon's capsule. Ocular movement was severely limited horizontally and even vertically. RESULTS: Postoperatively Patient 1 showed orthophoria in follow-up of 2 years. Patient 2 had 16PD of exotropia in follow-up of 13 months, which was cosmetically acceptable. Patient 3 obtained orthophoria after surgery and developed 10 degrees of left head turning to avoid diplopia. CONCLUSIONS: When a patient shows longstanding large angle exotropia with limitation of adduction, we may consider the MR loss. A reasonable treatment may be to align the eyes cosmetically in primary position by weakening the abducting power and suturing the anterior part of nasal Tenon's capsule to the MR insertion site after adhesiolysis.