Graves' eye disease, also called Graves' ophthalmopathy, is a problem that develops in people with an overactive thyroid caused by Graves' disease. Up to one-half of people with Graves' disease develop eye symptoms. Usually the eye symptoms are mild and easily treated.
Eye problems result from the swelling of tissues, muscles and fat in the socket behind the eye. This swelling causes exophthalmos, an abnormal protrusion of the eye, commonly associated with Graves' disease. The eyelids and membranes may retract as they swell. This can lead to exposure and infection of the cornea. The cornea is the transparent, dome-shaped "window" that lies directly over the eye's pupil and iris.
In serious cases, the swelling can cause the muscles that move the eyeball to become so stiff that the eye cannot move properly. Also, the swelling can put pressure on the optic nerve, impairing vision.