Correlation between uniocular deviation and duction changes following different decompression surgeries in thyroid eye disease

BACKGROUND: Postoperative ocular imbalance is an important problem for orbital decompression surgery in thyroid eye disease (TED). The aim of this study was to evaluate the changes in unilateral ocular deviation and duction following orbital decompression and discuss the biomechanics of ocular imbalance. METHODS: Fifty-four TED patients who underwent unilateral orbital decompression were included. Fifteen patients underwent 1-wall (deep lateral wall) decompression, 18 patients underwent 2-wall (deep lateral and medial wall) decompression and 21 patients underwent 3-wall (deep lateral, medial and inferior wall) decompression. Objective and subjective deviation of the operated eyes were evaluated using the prism test and synoptophore, respectively. Ocular ductions were measured using Hirschberg’s method. The diameters of the extraocular rectus were measured by computed tomography. RESULTS: Ocular deviation and duction showed no significant difference after 1-wall decompression (p = 0.25–0.89). Esotropia increased after 2-wall decompression (p = 0.001–0.02), and hypotropia increased after 3-wall decompression (p = 0.02). Adduction increased but abduction decreased following 2-wall and 3-wall decompression (p < 0.05). Infraduction increased following 3-wall decompression (p < 0.001). Additionally, the increase in esotropia was significantly correlated with the increase in adduction and with the decrease in abduction (r = 0.37–0.63, p < 0.05). There were significant correlations between the diameter of the medial rectus and the increase in esotropia, the increase in adduction and the decrease in abduction postoperatively (r = 0.35–0.48, p < 0.05). CONCLUSIONS: The changes in ocular deviation and duction were different after 1-wall, 2-wall and 3-wall orbital decompression. The increased contractile force of the rectus may be an important reason for strabismus changes after orbital decompression surgery.