Underactive thyroid (hypothyroidism) isn't usually associated with eye disease. In severe cases, however, hypothyroidism may cause swelling around the eyes and a loss of the hairs in the outer part of the eyebrows.

In some people, an eye problem known as Graves' ophthalmopathy may develop if hypothyroidism develops after treatment for Graves' disease — the most common form of overactive thyroid (hyperthyroidism). Graves' ophthalmopathy can cause eye discomfort, protruding eyeballs and vision changes.