To measure the orbital volume from facial CT scans using a semi-automatic computer program.

Axial and coronal slices of 35 facial CT scans were used to measure the orbital volume. The cross-sectional area was determined from each slice using a semi-automated computer program (MATLAB 2009a). Next, the orbital volume was calculated from serial reconstruction of the cross-sections.

The measured value in males was 26.34 ± 3.09 cm³ in the right orbit and 26.30 ± 3.21 cm³ in the left orbit from axial scans, and 26.58 ± 2.76 cm³ in the right orbit and 26.59 ± 2.75 cm³ in the left orbit from coronal scans. In females, the values were 23.84 ± 2.29 cm³ in the right orbit and 23.89 ± 2.33 cm³ in the left orbit from axial scans, and 24.06 ± 2.90 cm³ in the right orbit and 24.10 ± 2.82 cm³ in the left orbit from coronal scans. There was high positive correlation (r = +0.832, p = 0.0001) in measured orbital volume between axial and coronal scans.

The orbital volume measurement from facial CT scans using a semi-automatic computer program is very useful. This method should prove useful in further studies examining the correlation of orbital volume variation in many ophthalmologic disorders.