[Oculomotor risk after trans-palpebral bony decompression for thyroid-related orbitopathy]

To study oculomotor disorders after transpalpebral bony orbital decompression (TPBOD) for dysthyroid orbitopathy. Pathophysiology, risk factors, preventive and therapeutic care were examined.

Forty-four patients were included in this retrospective study (76 orbits). Thirteen patients underwent surgery for severe orbital inflammation or optic neuropathy and 31 for cosmetic rehabilitation. 21 previously had orbital radiotherapy. Class IV of NOSPECS classification, primary position of gaze, diplopia and Lancaster coordimetry were studied comparatively pre and postoperatively.

Diplopia appeared in 23.6% of the cases without deviation before surgery (tropia or phoria-tropia). Predictive factors were age and amblyopia whereas amount of retrodisplacement of the globe and radiotherapy were not. Lack of oculomotor restriction did not prevent from diplopia but may decrease its incidence. Unilateral decompression is more likely to create a vertical disorder. Pathophysiology is discussed.

Oculomotor disorders can be explained by several mechanisms. Some of them can be prevented. Each patient should be aware of the risk of diplopia.