ABSTRACT
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.
ABSTRACT
PURPOSE: This study aimed at evaluating the orbital anatomy of patients concerning the relevance of orbital anatomy in the etiology of EO (endocrine orbitopathy) and exophthalmos utilizing a novel approach regarding three-dimensional measurements. Furthermore, sexual dimorphism in orbital anatomy was analyzed. METHODS: Orbital anatomy of 123 Caucasian patients (52 with EO, 71 without EO) was examined using computed tomographic data and FAT software for 3-D cephalometry. Using 56 anatomical landmarks, 20 angles and 155 distances were measured. MEDAS software was used for performing connected and unconnected t-tests and Spearman´s rank correlation test to evaluate interrelations and differences. RESULTS: Orbital anatomy was highly symmetrical with a mean side difference of 0.3 mm for distances and 0.6° for angles. There was a small albeit statistically significant difference in 13 out of 155 distances in women and 1 in men concerning patients with and without EO. Two out of 12 angles showed a statistically significant difference between female patients with and without EO. Regarding sex, statistically significant differences occurred in 39 distances, orbit volume, orbit surface, and 2 angles. On average, measurements were larger in men. Concerning globe position within the orbit, larger distances to the orbital apex correlated with larger orbital dimensions whereas the sagittal position of the orbital rim defined Hertel values. CONCLUSION: In this study, little difference in orbital anatomy between patients with and without EO was found. Concerning sex, orbital anatomy differed significantly with men presenting larger orbital dimensions. Regarding clinically measured exophthalmos, orbital aperture anatomy is an important factor which has to be considered in distinguishing between true exophthalmos with a larger distance between globe and orbital apex and pseudoexophthalmos were only the orbital rim is retruded. Thus, orbital anatomy may influence therapy regarding timing and surgical procedures as it affects exophthalmos.