Unilateral and bilateral medial rectus recession in Graves' Orbitopathy patients

Purpose: To evaluate the effect of uni- and bilateral medial rectus recession on squint angle and ductions in Graves' Orbitopathy (GO) patients. Design: Retrospective case series. Materials and methods: Consecutive GO patients seen between January 2000 and March 2012 who were operated on one or both medial rectus muscles were selected for the study. Data regarding squint angle, abduction, and adduction were collected starting 3 months before surgery and 3 and 6-12 months after surgery. Results: 102 patients were eligible for inclusion. Of these, 24 patients were operated on one medial rectus and 78 on two medial rectus muscles. The dose-effect response was 1.0 [-0.6-3.8]degrees/mm in the unilateral and 1.4 [0.2-3.0] degrees/mm in the bilateral group (p = 0.000). In the bilateral group, the maximal abduction and adduction changed significantly (p = 0.000). However, the total duction range remained unchanged (unilateral: p = 0.525; bilateral: p = 0.137). The extent of the preoperative abduction did not influence the dose-effect response (r =-0.234; p = 0.040), nor did the muscle volume (unilateral p = 0.989; bilateral p = 0.397). Twenty-three patients (23%) needed additional horizontal squint surgery. Conclusion: In this large series of medial rectus recessions in patients with Graves' disease we found significantly lower dose-effect response ratios as compared to other studies. The amount of abduction deficit