The thyroid is an organ that lies at the base of your neck and is responsible for producing and sending hormones throughout the body. These hormones are then able to coordinate and regulate bodily functions related to metabolism and energy levels.
In some individuals, these hormones can be incorrectly produced in too large or too small amounts, diagnosed as hyperthyroidism or hypothyroidism respectively. Hyperthyroidism is more often associated with changes in the eyes compared to hypothyroidism, and these changes are explained below.
Signs and Symptoms of Thyroid Disease
Graves’ disease is a subtype of hyperthyroidism and is an autoimmune disorder that results in higher than normal levels of the hormones produced by the thyroid gland. It often presents in a patient’s 40’s or 50’s and is more common in women. It can be associated with weight loss, increased bowel movement frequency, sweating, heat intolerance, weakness and fatigue.
Hypothyroidism is, in contrast, associated with cold intolerance, weight gain, fatigue and a variety of other symptoms. In the early stages, the symptoms are mild and the patient may not be aware that a body system is no longer in balance. The most common cause of hypothyroidism is also due to autoimmune damage, called Hashimoto’s thyroiditis.
Eye Manifestations of Thyroid Eye Disease
Thyroid eye disease (TED) refers to the changes that occur in the eye as a result of changes to the thyroid. One common sign is the “stare” appearance, referring to the upper eyelid pulling backwards and upwards and exposing more of the eye. This makes the patient seem like they are staring intently at all times.
For this reason, dry eye signs and symptoms are exacerbated. Swelling or redness of the conjunctiva, the transparent tissue overlying the white part of the eye, and of the eyelids are other signs. There is also an increase in the incidence of uveitis, an inflammation within the eye.
Thyroid eye disease is also the leading cause of proptosis, where the eye is pushed forward from behind. This may be due to swelling of the eye muscles behind the eye due to the inflammatory pathology of the disease.
The swelling of these muscles causes limitations in eye movements and, for this reason, patients may experience double vision. The proptosis also contributes to the “stare” appearance.
Lastly, the worst change in the eye that can occur is damage to the optic nerve at the back of the eye that sends visual information to the brain. This has the potential to cause vision loss but is luckily rare in today’s society as the disease is often caught and treated as necessary before it gets to this level.
Thyroid eye disease has also been associated with thinning of the nerves responsible for central vision as well as thickening of the most inner layer of the nerve fibers.
