Thyroid dysfunction can affect the tissues around the eye and in the orbit in a condition called "thyroid related orbitopathy". Usually this is associated with hyperthyroidism (over-acting thyroid) as in "Grave's disease", although it can occur in a normal or even under-acting thyroid. It is felt to be an auto-immune problem where the immune system attacks the tissues around the eye, and possibly also the thyroid gland. This leads to a variety of eye symptoms.

• Swelling of the eyelids and tissues around the eyes.
• Eyelid "retraction", or excessive opening. This leads to a wide-open eye staring appearance. The white of the eye is often visible above and below the iris.
• Eye protrusion, where swelling of the tissues in the orbit behind the eye literally push the eye outward.
• Corneal drying and breakdown can occur from exposure of the cornea due to the eye protrusion and eyelid opening.
• Double vision can occur due to swelling and dysfunction of the eye muscles. Especially involved are the muscle the turn the eye downward. Thus, the eye becomes tethered and has difficulty looking upward, especially when turned out also. Double vision due to misalignment of the eyes occurs in certain positions of gaze, and it usually is a vertical double vision. It may be highly variable.
• Compression of the optic nerve in the orbit due to the swelling of the eye muscles can lead to visual loss, blind spots in the vision, loss of color vision, and swelling of the optic nerve. This can be an ophthalmic emergency and may take high dose steroids or surgery to reverse.

Thyroid related eye problems tend to come and go, and the eyes may remain unaffected for long periods of time between attacks. Supportive treatment during symptomatic periods such as eye lubrication and steroids to reduce swelling may help.