Measurement of the globe proptosis by CT and its accuracy in patients with unilateral orbital fracture

Objective To evaluate the accuracy of measurement of the globe proptosis by CT in patients with unilateral orbital fracture. Methods 25 patients with unilateral orbital fracture were included. CT was performed before and after operation. The globe proptosis on the unaffected side was measured before and after operation by using Hertel exophthalmometer(HE), CT images with orbital lateral rim(OLR) and the optic nerve foramen(ONF) as reference points. The accuracy was evaluated comparably by statistical analyses. Results The preoperative and postoperative average globe proptoeis were (13.9± 3.1) mm and (12.5±2.2) mm in HE group, (16.1±2.6) mm and (15.7±2.3) mm in the OLR group, (45.3±4.8) mm and(46±3.9) mm in the ONF group, showing a significant difference between the pre-and post-operative results in HE group, but not in OLR and ONF groups. Conclusions CT measurement with the orbital lateral rim as reference point is more reliable than Hertel exophthalmometer measurement for globe proptosis. Key words: Globe proptosis;  CT measurement;  Orbital fracture