Passive ocular proptosis.

Two patients with oculomotor neuropathy demonstrated passive ocular proptosis. In both instances, there was no evidence of a pathological process exerting a vector of force through the orbital opening. The proptosis is caused by a combination of the loss of the normal backward force exerted by the ocular recti muscles and the presence of a small anteriorly directed force exerted by the ocular obliques. Computerized tomography of the orbital and retro-orbital regions was of value in establishing the diagnosis and excluding orbital disease in one patient. The role of computerized tomography in the evaluation of the patient with ocular proptosis is discussed.