Definition of Exophthalmos

Exophthalmos – bulging outward of the eye, sometimes called poptosis. Most exophthalmos results from Graves’s disease and is a classic symptom of this form of hyperthyroidism. Thyroidrelated exophthalmos results from swelling of the tissues around the eye and within the orbit that develops in reaction to the high levels of thyroid hormone present in the circulation.

Other causes of exophthalmos include orbital cellulitis, the autoimmune disorder Wegener’s granulomatosis, and fracture of the facial or orbital bones that push the eye out of place.

Less common causes of exophthalmos include tumors of the eye, optic nerve, or brain that protrude into the orbital socket and aneurysm (ballooning of the arterial wall) of the internal carotid artery, a branch of which runs behind the eye. Exophthalmos can affect one eye (unilateral) or both eyes (bilateral), and when bilateral can affect one eye more prominently than the other.

Exophthalmos can cause significant and permanent vision impairment, and requires prompt treatment.

The diagnostic path begins with an ophthalmologic examination and blood tests to assess thyroid function. When Graves’s disease or hyperthyroidism is the cause, treatment to restore appropriate levels of thyroid hormones often though not always returns the eye to its normal position.

Persistent exophthalmos may prevent the eyelids from closing over the eye, exposing the cornea to excessive dryness and potential trauma. Untreated exophthalmos results in vision impairment that can progress to blindness.


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