Computerized tomography of the orbit.

The potential for using CT to diagnose orbital lesions is clearly demonstrated in this chapter. The patients discussed were all suffering from proptosis and had other complaints such as visual disturbances, pain, or ophthalmoplegia. CT is superior to ultrasonography in its ability to reproduce anatomical structures, including the retroocular space, bony walls of the orbit, and extraorbital regions, such as ethmoid sinuses and the cranial cavity. Such reproduction helps distinguish lesions arising within the orbit from those invading the orbit from outside. CT not only defines the extent of a lesion but also provides information about the physical properties of the tissue. The remarkable difference on CT between proptosis caused by thyrotoxic disease and that caused by intraorbital tumor or pseudotumor is a striking example of the way in which CT may contribute to more accurate diagnosis.