How Common Is Thyroid Eye Disease?

There are two phases of thyroid eye disease:

1. The active stage is the period in which progressive inflammation, swelling, and tissue changes occur. This typically lasts for about 6 months to 2 years.
2. The inactive or burnt-out stage is the stable phase when active inflammation settles down and the disease progression stops. In some patients, the eyes return to normal whereas in others permanent changes, such as double vision and bulging eyes, may remain.

Thyroid eye disease is caused by an autoimmune process. In this condition, the body sees a part of itself as foreign and reacts to it as it would to any bacteria or viruses.

The immune system attacks both the thyroid and the tissues around the eye. Though TED is seen in all thyroid disorders, it is more often associated with hyperthyroidism or Graves disease.

TED patients produce antibodies that bind to fibroblast cells (connective-tissue forming cells) within the eye socket. This causes the fibroblast cells to produce chemical signals and release biological materials that lead to swelling and congestion in and around the eye socket. This causes inflammation and swelling of the fat and muscle tissues around the eye, causing bulging of the eyes, retraction of the eyelids, and double vision.

Some common signs and symptoms of thyroid eye disease include:

• Red and puffy eyelids, which are more obvious in the morning.
• Irritation and redness of eyes.
• Dry eyes, watering, grittiness, and soreness in the eye.
• Corneal scarring.
• Bags under the eyes.
• Eyelid retraction. The upper eyelid rises to a higher position making the white of the eye more visible causing staring eyes.
• Exophthalmos or proptosis (bulging of the eyes).
• Difficulty in closing eyelids.
• Strabismus (also called squint).
• Swelling or feeling of fullness in one or both upper eyelids.
• Blurring or dimming of vision due to optic nerve compression.
• Painful orbits (eye sockets).
• Pain in or behind the eye especially when looking up, down, or sideways.
• Difficulty moving the eyes.
• Diplopia (double vision due to pain or restricted eye movements).
• Discomfort to bright lights. 
• Pressure sensation with a headache.

The severity of thyroid eye disease

Most patients have only mild symptoms. However, around 3-5% of patients with thyroid eye disease may have serious problems, including vision loss.