Globe displacement is the most common clinical manifestation of an orbital abnormality. It usually results from a tumor, a vascular abnormality, an inflammatory process, or a traumatic event.
Several terms are used to describe the position of the eye and orbit. Proptosis denotes a forward displacement or bulging of a body part and is commonly used to refer to protrusion of the eye. Exophthalmos specifically means proptosis of the eye and is sometimes used to describe the bulging of the eye associated with TED. Exorbitism refers to an angle between the lateral orbital walls that is greater than 90°, which is usually associated with shallow orbital depth. This condition contrasts with hypertelorism, or telorbitism, which refers to a wider-than-normal separation between the medial orbital walls. Generally, exorbitism and hypertelorism refer to congenital abnormalities. Telecanthus refers to a wide intercanthal distance. The eye may also be displaced vertically (hyperglobus or hypoglobus) or horizontally by an orbital mass. Retrodisplacement of the eye into the orbit, called enophthalmos, may occur as a result of volume expansion of the orbit (fracture), in association with orbital varix, or secondary to sclerosing orbital tumors (eg, metastatic breast carcinoma).
Proptosis often indicates the location of a mass because the globe is usually displaced away from the site of the mass. Axial displacement is caused by retrobulbar lesions such as cavernous hemangioma, glioma, meningioma, metastases, arteriovenous malformations, and any other mass lesion within the muscle cone. Nonaxial displacement is caused by lesions with a prominent component outside the muscle cone. Superior displacement is produced by maxillary sinus tumors invading the orbital floor and pushing the globe upward. Inferomedial displacement can result from dermoid cysts and lacrimal gland tumors. Inferolateral displacement can result from frontoethmoidal mucoceles, abscesses, osteomas, and sinus carcinomas. Bilateral proptosis in adults is caused most often by TED; however, bilateral orbital involvement from lymphoma, vasculitis, NSOI, metastatic tumors, carotid cavernous fistulas, cavernous sinus thrombosis, or leukemic infiltrates can also produce bilateral proptosis. Unilateral proptosis in adults is also most frequently caused by TED. In children, bilateral proptosis may be caused by metastatic neuroblastoma, leukemic infiltrates, TED, or NSOI.
Exophthalmometry is a measurement of the anterior–posterior position of the globe, generally from the lateral orbital rim to the anterior corneal surface (Hertel exophthalmometry; Fig 2-1). On average, the globes are more prominent in men than in women and more prominent in black patients than in white patients. An asymmetry of greater than 2 mm between an individual patient’s eyes suggests proptosis or enophthalmos. Proptosis may best be appreciated clinically when the examiner looks up from below with the patient’s head tilted back (the so-called worm’s-eye view;Fig 2-2).
Pseudoproptosis is either the simulation of abnormal prominence of the eye or a true asymmetry that is not the result of increased orbital contents. Diagnosis should be postponed until a mass lesion has been ruled out. Causes of pseudoproptosis are
asymmetric orbital size
asymmetric palpebral fissures (usually caused by ipsilateral eyelid retraction or facial nerve paralysis or contralateral ptosis)
Ocular movements may be limited in a specific direction of gaze by neoplasm or inflammation. In TED, the inferior rectus is the muscle most commonly affected, which restricts globe elevation and may cause hypotropia in primary gaze and restriction of upgaze. A large or rapidly enlarging orbital mass can also impede ocular movements, even in the absence of direct muscle invasion.
Eyelid abnormalities are common in TED. The von Graefe sign refers to the delay in the upper eyelid’s descent (“lid lag”) during downgaze and is highly suggestive of a diagnosis of TED. In fact, such lid lag and the retraction of the upper and lower eyelids are the most common physical signs of TED.
Several eyelid signs of orbital pathology are seen in childhood disorders. Capillary hemangiomas in the orbit often involve the skin of the eyelids, producing strawberry birthmarks that usually grow during the first year of life and then regress spontaneously. Plexiform neurofibromas often involve the lateral upper eyelids as well as the orbits, producing a “bag of worms” appearance and texture beneath the skin and conjunctiva and sometimes causing an S-shaped curvature of the upper eyelids. Bilateral eyelid ecchymoses may occur in children with metastatic neuroblastoma.
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