Exophthalmos is an abnormal anterior protrusion of the eyeball. It is measured with an instrument called: Hertel, that records the position of the surface of the cornea to the lateral edge of the orbit.
Exophthalmos appearance implies the existence of a lesion that replaces the orbit space. Any patient with exophthalmos should do a CT or MRI examination, unless there is a safe diagnosis of Graves ophthalmopathy.
1. Graves ophthalmopathy is a major cause of exophthalmos in adults. Orbital inflammation and impaired extrinsic eye muscles, especially the right medial and right inferior are responsible for protrusion of the eyeball. Exposure of cornea, eyelid retraction, conjunctival congestion, sight limiting, double vision and blindness consecutive to optic nerve compression are cardinal symptoms.
Compression of the optic nerve should be resolved promptly by radiotherapy or orbital decompression to prevent permanent vision loss.
2. Orbital pseudotumor is an inflammatory syndrome, idiopathic (of unknown cause), of the orbit, frequently confused with Graves ophthalmopathy. Symptoms include pain, limitation of eye movements, exophthalmos and congestion. Tests for sarcoidosis, Wegener’s granulomatosis and other orbital vasculitis or collagen vascular diseases are negative. Imaging examinations often reveal swollen eye muscles (orbital myositis) with enlarged tendons.
Instead, in Graves ophthalmopathy, tendons of the eye muscles are usually spared. Tolosa-Hunt syndrome may be considered an extension of orbital pseudotumor through superior orbital fissure at the cavernous sinus level.
The diagnosis of orbital pseudotumor is difficult. Orbital biopsy frequently provides data highlighting nonspecific infiltration of adipose tissue with lymphocytes, plasma cells and eosinophils. A spectacular response to therapeutic test with systemic glucocorticoids indirectly provides the best confirmation of the diagnosis.
3. Orbital cellulitis causes pain, erythema of eyelid, exophthalmos, conjunctival chemozis, reduced motility, decreased visual acuity, afferent pupillary defect, fever and leukocytosis. Often comes from a paranasal sinus, particularly through nearby dissemination of infection from the ethmoid sinus.
A history of recent upper respiratory tract infection, chronic sinusitis, viscous mucus secretions or dental diseases are significant in any patient suspected of orbital cellulitis. Blood cultures should be performed, but they are usually negative. Most patients respond to empiric treatment with broad-spectrum antibiotics intravenously. Sometimes , orbital cellulitis is developing extremely severe with massive exophthalmos, blindness, septic thrombosis of cavernous sinus and meningitis. To prevent this disaster, orbital cellulitis should be approached aggressively even in the early stages by antibiotics started immediately and by doing imaging examinations of the orbits.
Prompt surgical drainage of an orbital abscess or a rhinosinusitis is indicated in situations where, despite antibiotic treatment the optic nerve function deteriorates.
4. Orbital tumors produce progressive exophthalmos, painless. The most common primary tumors are hemangioma, lymphangioma, neurofibroma, dermoid cyst, optic nerve glioma, optic nerve meningioma and benign mixed tumors of the lacrimal gland.
Metastatic tumors of the orbit occur frequently in breast cancer, lung carcinoma and lymphoma. Diagnosis is done by fine needle aspiration, followed by emergency radiation can sometimes save the vision.
5. Carotid cavernous fistulas with anterior drainage through orbit produce exophthalmos, diplopia, glaucoma and the occurrence of red conjunctival vessels, sinuous. Direct fistulas usually occur after trauma. They are easily diagnosed due to dramatic signs caused by shunting flow and increased pressure.
Indirect fistulas or arteriovenous dural malformations occur more likely spontaneously, especially in elderly women.
The signs are more subtle and the diagnosis is frequently missed. The combination of mild exophthalmos, diplopia, increased muscles and ocular congestion is frequently confused with thyroid ophthalmopathy. The presence of a noise during head auscultation or reported by the patient is a valuable diagnostic clue. Imaging examinations show an increased superior ophthalmic vein. Cavernous carotid shunts can be removed by intravascular embolization.