Thyroid dysfunction can cause a number of ocular problems. The most common is dry eye, as the hormonal changes can decrease tear production. Graves disease can stiffen the eye muscles located behind the eyeball and cause fibrous deposits that make the eye muscles swell and expand. This can actually make the eyes protrude forward in a condition called exophthalmos. Thyroid dysfunction can also cause the upper eyelid to retract which can give a person a surprised or wide-eyed appearance. Finally, thyroid muscle dysfunction can cause double vision (diplopia).