Spontaneous orbital decompression in thyroid eye disease: new measurement methods and its influential factors.

PURPOSE: To evaluate spontaneous decompression of the medial orbital wall and orbital floor in thyroid eye disease using new measurement methods and to analyze the influential factors. METHODS: This retrospective study included 86 patients (172 sides). Regarding evaluation of spontaneous medial orbital decompression, an anteroposterior line was drawn between the posterior lacrimal crest and the junction between the ethmoid bone and corpus ossis sphenoidalis. The bulged and/or dented areas from that line were measured. Regarding evaluation of spontaneous orbital floor decompression, the length of the perpendicular distance from a line that was drawn between the inferior orbital rim and the orbital process of palatal bone to the tip of the superior bulge of the orbital floor was measured. RESULTS: Multivariate linear regression analysis revealed that the maximum cross-sectional areas of the superior rectus/levator palpebrae superioris complex (P = 0.020) and medial rectus muscle (P = 0.028) were influential factors for spontaneous decompression of medial orbital wall (adjusted r2 = 0.090; P < 0.001), whereas the number of cycles of steroid pulse therapy (P = 0.002) and the maximum cross-sectional area of the inferior rectus muscle (P = 0.007) were the ones for that of the orbital floor (adjusted r2 = 0.096; P < 0.001). CONCLUSION: We believe that the identification of multiple influential factors of spontaneous decompression of the medial orbital wall and orbital floor will be helpful for better understanding and planned management of thyroid eye disease patients undergoing orbital decompression surgery.