TED is an autoimmune disease in which the eye muscles and fatty tissue behind the eye become inflamed. This inflammation can push the eyes forward (“staring” or “bulging”) or cause the eyes and eyelids to become red and swollen. In some individuals, the inflammation may involve the eye muscles, causing the eyes to become out of line, leading to double vision. In rare cases, TED can cause blindness from pressure on the nerve in the back of the eye or ulcers that form on the front of the eye (cornea).