Orbital Morphology for Decompression Surgery in Thyroid Eye Disease Using 2-D Orbital CT and 4 Parameters

ABSTRACT

PURPOSE: To present easily measurable 2D orbit computed tomography (CT) reference data that can be used in a preoperative study for orbital decompression and classification of individual orbital morphologies. METHODS: The study sample was composed of 77 patients with orbital contusion (42 Asian males + 35 Asian females = 154 orbits) who visited the emergency room of the Korea University Guro Hospital from September 2012 to June 2013. Patients with orbital wall fracture, retrobulbar hemorrhage, or eyeball rupture were excluded. Medical records including 2D orbit or facial bone CT were retrospectively reviewed and 4 orbital parameters (orbital length, OL; globe length, GL; GL/OL ratio and 2D cone angle) were measured. RESULTS: The average OL was 42.53 +/- 2.46 mm (35.63-49.09 mm) and average GL was 24.83 +/- 1.09 mm (22.75-28.13 mm). The average GL/OL ratio using these 2 parameters was 0.59 +/- 0.04 (0.50-0.68). The posterior cone angle was on average, 45.96 +/- 5.91degrees (29.35-60.04degrees). CONCLUSIONS: Simple measurement of 4 parameters using 2D orbit CT and classification of Asian individual orbital morphology may help in the choice of the most effective surgical technique for decompression surgery in thyroid eye disease patients.