Evaluation of Globe Position Asymmetry in Endocrine Orbitopathy Patients and a Control Group - A Computed Tomography-Based 3D Cephalometric Analysis.

Background: Previous studies have shown that patients suffering from endocrine orbitopathy (EO) seem to present with profound asymmetry in proptosis. As asymmetry might pose a major problem in planning decompression surgery, information on the amount of variation between sides and a concise evaluation method should be available. Therefore, a study based on a concise 3D cephalometric analysis was conceived to evaluate globe position.

Methods: A 3D-cephalometric analysis was performed on computed tomography (CT) data from 52 orbitopathy and 54 control data sets. Using 36 anatomic landmarks, 33 distances were evaluated to measure sagittal, vertical, and horizontal globe position.

Results: EO patients presented with marked exophthalmos and statistically significant asymmetry. Depending on the 2 measured distances, 38% and 42%, respectively, presented sagittal asymmetry of >2 mm, and 12% and 13%, respectively, presented with sagittal asymmetry >4mm. No such asymmetry was seen in the control group. Furthermore, EO patients showed a larger interglobe distance due to lateral globe position. Marked asymmetry correlated with male sex. Proptosis measured to the deep bony orbit correlated with values measured to the orbital aperture or with constructed Hertel values.

Conclusions: Use of 3D cephalometry and CT-based analysis confirmed findings from previous clinical studies on profound sagittal asymmetry in EO. Endocrine orbitopathy leads to a sagittal-lateral globe displacement that is even more pronounced in the current study than in earlier investigations. Concerning surgical therapy, presurgical asymmetry, especially if profound, has to be considered to achieve an esthetic symmetrical outcome. Use of 3D orbital analysis is an appropriate method to describe globe position beyond clinical measurements.