Exophthalmos (also called exophthalmus, exophthalmia, proptosis, or exorbitism) is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral (as is often seen in Graves' disease) or unilateral (as is often seen in an orbital tumor). Complete or partial dislocation from the orbit is also possible from trauma or swelling of surrounding tissue resulting from trauma. In the case of Graves' disease, the displacement of the eye results from abnormal connective tissue deposition in the orbit and extraocular muscles, which can be visualized by CT or MRI.