Bony Orbital Volume Measurement in Normal Adults using CT Scan

ABSTRACT

PURPOSES: To measure orbital volumes in normal adults using computed tomography to help make proper diagnoses and treatments of orbital diseases. METHODS: Among the patients who had CT scan taken between July 1995 and March 2001, we evaluated the scan results of 142 orbits in 112 adults over the age of 20 years with no pathology in the orbit. The anterior and posterior borders were defined as the zygomatico-frontal suture and the optic canal, respectively. We summed up the area according to the serial coronal views covering the whole orbit, calculated the volume of the whole orbit mathematically and compared the volume between the left and right eyes according to the sex. RESULTS: The normal mean orbital volume of male adults was 24.51+/-2.89 mm(3) (range, 19.3~31.9 mm(3)), and that of women, 21.59+/-2.19 mm(3) (range 18.0~26.5 mm(3)), showing the difference of 2.92 mm(3) (p=0.049) between the sexes. When both orbital volume measurements were summed up, the volume of the left and right orbits was 24.41 cm(3) and 24.10 cm(3) in adult men, respectively. On the other hand, it was 21.54 cm(3) and 21.45 cm(3) in adult women, respectively. The differences in each group (0.31 cm(3), male; 0.09 cm(3), female) showed no statistical significance (p=0.064, male; 0.698, female). CONCLUSIONS: We could measure orbital volumes of normal adults with accurate data on orbital structures by orbital CT. We believe our data will be very helpful in diagnosis of orbital bone fractures, anophthalmic socket, tumors and abnormalities of the orbit. Furthermore, they will play an important role in treatment as well.