Surgical therapy for extreme upshoot in Duane's retraction syndrome A case presentation.

Up to 25% of the eyes affected with Duane's syndrome show upshoot and/or downshoot in attempted adduction. This is thought to be caused by the tight horizontal muscles both contracting in attempted adduction (leash or bridle effect) due to abnormal firing of the lateral rectus muscle through which the globe slips beneath the muscle. Surgical procedures successful in correcting the very disturbing cosmesis of gaze are posterior fixation, recession of the horizontal rectus muscles or splitting of lateral recti muscles insertion. The authors report on a 27-year-old male with Duane's syndrome type III with extreme upshoot in adduction. After recession of both horizontal muscles the upshoot on attempted adduction was no longer present postoperatively. At one year follow-up a very discrete upshoot in attempted adduction could be documented. The resolving of the upshoot postoperatively could be explained by the bridle mechanism alone. The low grade upshoot in attempted adduction at one year follow-up could have been caused by new adhesions of the check ligaments and Tenon's capsule at the level of the lateral rectus muscle resulting from surgery itself. The possibility of an anomalous cyclovertical innervation playing a role in the vertical anomalous movements as Duane originally hypothetized cannot be excluded.