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Proptosis is protrusion of the eyeball. Exophthalmos means the same thing, and this term is usually used when describing proptosis due to Grave's disease. Disorders that may cause changes in the appearance of the face and eyes that resemble proptosis but are not include hyperthyroidism without infiltrative eye disease, Cushing's disease, and severe obesity.
Etiology
The most common cause is Graves' disease (see Table 9: Symptoms of Ophthalmologic Disorders: Some Causes of Proptosis ), which causes edema and lymphoid infiltration of the orbital tissues.
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Table 9
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| Some Causes of Proptosis |
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Cause
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Suggestive Findings
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Diagnostic Approach
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Graves' disease
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Local symptoms: Pain, lacrimation, dry eyes, irritation, photophobia, ocular muscle weakness causing diplopia, vision loss caused by optic nerve compression
Systemic symptoms: Palpitations, anxiety, increased appetite, weight loss, insomnia (see Thyroid Disorders: Symptoms and Signs)
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Thyroid function tests
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Carotid-cavernous sinus or dural-cavernous sinus fistula
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Pulsating proptosis with an orbital bruit
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Magnetic resonance angiography
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Cavernous sinus thrombosis
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Ophthalmoplegia, headache, ptosis, decreased visual acuity, fever
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CT or MRI
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Congenital glaucoma and unilateral high myopia
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Tearing, blepharospasm, redness
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Funduscopy by ophthalmologist
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Orbital cellulitis
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Redness, fever, pain, impaired visual acuity, impaired or painful extraocular movements
Usually unilateral
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CT or MRI
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Orbital tumors (eg, lymphoma, hemangioma, vascular malformations)
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Decreased visual acuity, diplopia, pain
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MRI or CT
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Retrobulbar hemorrhage
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Decreased visual acuity, diplopia, pain, ophthalmoplegia, risk factors
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Immediate CT or treatment based on clinical findings
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Spheno-orbital meningioma
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Pain, headache, visual field defects, ophthalmoplegia
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MRI or CT
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Evaluation
Rate of onset may provide a clue to diagnosis. Sudden unilateral onset suggests intraorbital hemorrhage (which can occur after surgery, retrobulbar injection, or trauma) or inflammation of the orbit or paranasal sinuses. A 2- to 3-wk onset suggests chronic inflammation or orbital inflammatory pseudotumor (non-neoplastic cellular infiltration and proliferation); slower onset suggests an orbital tumor.
Ocular examination findings typical of hyperthyroidism but unrelated to infiltrative eye disease include eyelid retraction, eyelid lag, temporal flare of the upper eyelid, and staring. Other signs include eyelid erythema and conjunctival hyperemia. Prolonged exposure of larger-than-usual areas of the eyeball to air causes corneal drying and can lead to infection and ulceration.
Testing:
Proptosis can be confirmed with exophthalmometry, which measures the distance between the lateral angle of the bony orbit and the cornea; normal values are < 20 mm in whites and < 22 mm in blacks. CT or MRI is often useful to confirm the diagnosis and to identify structural causes of unilateral proptosis. Thyroid function testing is indicated when Graves' disease is suspected.
Treatment
Lubrication to protect the cornea is required in severe cases. When lubrication is not sufficient, surgery to provide better coverage of the eye surface or to reduce proptosis may be required. Systemic corticosteroids (eg, prednisone 1 mg/kg po once/day for 1 wk, tapered over ≥ 1 mo) are often helpful in controlling edema and orbital congestion due to thyroid eye disease or inflammatory orbital pseudotumor. Other interventions vary by etiology. Graves' exophthalmos is not affected by treatment of the thyroid condition but may lessen over time. Tumors must be surgically removed. Selective embolization or, rarely, trapping procedures may be effective in cases of arteriovenous fistulas involving the cavernous sinus.
Last full review/revision April 2009 by Kathryn Colby, MD, PhD
Content last modified April 2009
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