Special attention should be given to visual acuity, pupillary responses, color vision and visual field testing, ocular motility, globe position, and ophthalmoscopy. Diagnostic and imaging studies are often required in addition to the basic workup.
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 or exophthalmos denotes a forward displacement or protrusion of the globe. Exorbitism refers to an angle between the lateral orbital walls that is greater than 90°, which may also be 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 are congenital or traumatic abnormalities. Telecanthus denotes an abnormal increased distance between the medial canthi. 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, silent sinus syndrome), in association with orbital varix, or secondary to sclerosing orbital tumors (eg, metastatic breast carcinoma).
Because the globe is usually displaced away from the site of a mass, proptosis often indicates the location of that mass. Axial displacement is usually indicative of an intraconal mass behind the globe; such lesions include cavernous hemangioma, glioma, meningioma, metastases, and arteriovenous malformations. 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 orbital dermoid cysts and lacrimal gland tumors. Inferolateral displacement can result from frontoethmoidal mucoceles, abscesses, osteomas, and ethmoid sinus carcinomas.
In adults, bilateral proptosis is caused most often by thyroid eye disease (TED); however, other disorders can also produce bilateral proptosis, including lymphoma, vasculitis, NSOI, metastatic tumors, carotid-cavernous fistulas, cavernous sinus thrombosis, and leukemic infiltrates. TED is also the most common cause of unilateral proptosis in adults. In children with bilateral proptosis, the clinician should consider TED, NSOI, metastatic neuroblastoma, or leukemic infiltrates. Unilateral proptosis in children should raise concern for orbital cellulitis, vascular malformation, and malignancy.
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 2-2A). The Naugle exophthalmometer uses the frontal and maxillary bones as its reference structures (Fig 2-2B); this exophthalmometer is useful in trauma patients when the lateral orbital rim has been displaced or in patients who have had the lateral orbital rim removed as part of decompressive surgery.
Globe position varies by gender and ethnicity. The mean normal values are 16.5 mm in white males, 18.5 mm in black males, 15.4 mm in white females, and 17.8 mm in black females. Asymmetry of greater than 2 mm between an individual patient’s eyes suggests proptosis or enophthalmos. These conditions 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 2-3).
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 include the following:
enlarged globe or irregular cornea (eg, axial myopia, staphyloma, keratoconus)
contralateral enophthalmos (prior orbital trauma, surgery, silent sinus syndrome)
asymmetric orbital size
asymmetric palpebral fissures (usually caused by ipsilateral eyelid retraction, facial nerve paralysis, or contralateral ptosis)
congenital deformity (microphthalmia)
Figure 2-2 Types of exophthalmometers. A, The Hertel exophthalmometer uses the lateral canthus as its reference point. B, The Naugle exophthalmometer uses the frontal and maxillary bones as reference points. It can measure both proptosis and hyperglobus or hypoglobus.
(Courtesy of University of Iowa.)
Figure 2-3 “Worm’s-eye view” position. Note enophthalmos of the right eye.
(Courtesy of Bobby S. Korn, MD, PhD.)
Ocular movements may be restricted in a specific direction of gaze by neoplasm or inflammation. In TED, the inferior rectus is the muscle most commonly affected; this mechanically limits 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 is a 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 (see Chapter 4 in this volume).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.