There is considerable controversy regarding the performance of strabismus surgery in patients with Graves' orbitopathy (GO). The spectrum of recommendations extends from variable dose-effect correlations for these procedures (Esser, 1994; Mourits et al., 1990; Nguyen et al., 2002) to individualized approaches such as passive intraoperative motility testing and postoperative adjustment of sutures (Lueder et al., 1992; Nguyen et al., 2002), and to local anesthesia for intraoperative assessment of active motility (Kalpadakis et al., 2004). Furthermore, prior decompression surgery is known to contribute to an unpredictable outcome (Eckstein and Esser, 2003; Esser, 1994). We retrospectively analyzed the charts of 34 patients undergoing strabismus surgery for this condition, with the aim to evaluate whether muscle size or preoperative muscle impairment are related to the outcome of surgery.