Exophthalmos
Exophthalmos: Excerpt from Professional Guide to Diseases (Eighth Edition)
Exophthalmos (also called proptosis) is the unilateral or bilateral bulging or protrusion of the eyeballs or their apparent forward displacement (with lid retraction). The prognosis depends on the underlying cause.
Causes
Exophthalmos commonly results from hyperthyroidism, particularly ophthalmic Graves’disease in which the eyeballs are displaced forward and the lids retract. Unilateral exophthalmos may also result from trauma (such as fracture of the ethmoid bone, which allows air from the sinus to enter the orbital tissue, displacing soft tissue and the eyeball). Exophthalmos may also stem from hemorrhage, varicosities, thrombosis, and edema, all of which similarly displace one or both eyeballs.
Other systemic and ocular causes include:
❑ infection — orbital cellulitis, panophthalmitis, and infection of the lacrimal gland or orbital tissues
❑ parasitic cysts — in surrounding tissue
❑ pseudoexophthalmos paralysis of extraocular muscles — relaxation of eyeball retractors, congenital macrophthalmia, and high myopia
❑ tumors and neoplastic diseases — in children, rhabdomyosarcomas, leukemia, gliomas of the optic nerve, dermoid cysts, teratomas, metastatic neuroblastomas, and lymphoma; in adults, lacrimal gland tumors, mucoceles, cavernous hemangioma, meningiomas, metastatic carcinomas, and lymphoma.
Signs and symptoms
The obvious effect is a bulging eyeball, commonly with diplopia, if extraocular muscle edema causes misalignment. (See Recognizing exophthalmos.) A rim of the sclera may be visible below the upper lid as lid retraction occurs, and the patient may blink infrequently. Other symptoms depend on the cause: pain may accompany traumatic exophthalmos; a tumor may produce conjunctival hyperemia or chemosis; retraction of the upper lid predisposes to exposure keratitis. If exophthalmos is associated with cavernous sinus thrombosis, the patient may exhibit paresis of the muscles supplied by cranial nerves III, IV, and VI; limited ocular movement; and a septic-type (high) fever.
Diagnosis
Exophthalmos is usually obvious on physical examination; exophthalmometer readings confirm diagnosis by showing the degree of anterior projection and asymmetry between the eyes (normal bar readings range from 12 to 20 mm). The following diagnostic measures identify the cause:
❑ Computed tomography scan or magnetic resonance imaging detects swollen extraocular muscles or lesions within the orbit.
❑ Culture of discharge determines the infecting organism; sensitivity testing indicates appropriate antibiotic therapy.
❑ Biopsy of orbital tissue may be necessary if initial treatment fails.
Treatment
Eye trauma may require cold compresses for the first 24 hours, followed by warm compresses, and prophylactic antibiotic therapy. After edema subsides, surgery may be necessary in a small percentage of cases. Eye infection requires treatment with broad-spectrum antibiotics during the 24 hours preceding positive identification of the organism, followed by specific antibiotics. A patient with exophthalmos resulting from an orbital tumor may initially benefit from antibiotic or corticosteroid therapy. Eventually, surgical exploration of the orbit and excision of the tumor, enucleation, or exenteration may be necessary. Radiation and chemotherapy may be used when primary orbital tumors can’t be fully excised as encapsulated lesions, such as in rhabdomyosarcoma lesions.
Treatment for Graves’ disease may include antithyroid drug therapy or partial or total thyroidectomy to control hyperthyroidism; initial high doses of systemic corticosteroids, such as prednisone, for optic neuropathy and, if lid retraction is severe, protective lubricants.
Surgery may include orbital decompression (removal of the superior and lateral orbital walls) if vision is threatened, followed by lid (blepharoplasty) and muscle surgery.
Special considerations
❑ Administer medication as ordered.
❑ Record the patient’s response to therapy.
❑ Apply cold and warm compresses, as ordered, for fracture or other trauma.
❑ Provide postoperative care.
❑ Explain tests and procedures and give emotional support.
❑ Protect the exposed cornea with lubricants to prevent corneal drying.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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