Exophthalmos

Protrusion of one or both eyeballs caused by a swelling of the soft tissue in the eye socket. It is most commonly associated with thyrotoxicosis. Other causes include an eye tumour, inflammation, or an aneurysm behind the eye. Exophthalmos may restrict eye movement and cause double vision. In severe cases, increased pressure in the socket may restrict blood supply to the optic nerve, causing blindness. The eyelids may be unable to close, and vision may become blurred due to drying of the cornea. In exophthalmos due to thyroid disease, treatment of the thyroid disorder may relieve the exophthalmos, but, if the cause is Graves’ disease, exophthalmos may persist even if thyroid function returns to normal. Early treatment of the condition usually returns vision to normal. Occasionally, surgery may be required to relieve pressure on the eyeball and optic nerve.