Thyroid Eye Disease

Thyroid Eye Disease (TED) is an orbital and ocular disease associated with thyroid gland problems, principally hyperthyroidism (Grave’s Disease), but which can also be related to thyroid conditions such as hyperthyroidism and Hashimoto’s thyroiditis. Thyroid eye disease is an autoimmune process of which the causes are unknown. The patient’s own immune system generates antibodies that attack the thyroid glands and the structures that surround the eyes (eye muscles, orbital fat). These antibodies cause inflammation of the affected structures. The eye, eye muscles and orbit fat are surrounded by the orbital bone wall. The inflamed eye muscles and the orbital fat increase in size but as the orbital cavity is rigid and made of bone it’s unable to cope with the increased volume and, consequently, the orbital contents move forwards and the eyes are pushed outwards. The medical term for this process is exophthalmos or proptosis. Other effects of thyroid eye disease are:

• Eye discomfort: irritation, feeling under the weather, watery eyes.

• Blurry vision and inability to read for an extended amount of time.

• Strabismus (cross-eyed) with double vision.

• Retro-ocular pain or pain from eye movement.

• Eyelid retraction.

• Inability to completely close eyelids.

• Increase in intraocular pressure.

In serious cases an optic nerve could become trapped resulting in a reduction in vision and perception of colours.

How can it be treated?

TED has two phases:

• The first phase consists of inflammation. This phase usually lasts between 6 and 12 months and generally stops suddenly. Mild cases do not tend to require any specific treatment. Moderate and severe cases require anti-inflammatory treatment to reduce inflammation of the eye muscles and orbital fat. As a first option corticosteroids are usually administered into the veins. Other options are radiotherapy and immunosuppressants.

• The second phase is the scarring phase. This phase begins once inflammation has finished. There is no longer an active inflammatory process but there is fibrosis and scarring in the tissue that has undergone inflammation which can cause persistent eye problems. The shorter and less serious the previous stage, the less significant the scarring of the ocular structures. Treatment in this phase involves surgery to correct the problems that persist once inflammation has disappeared such as exophthalmos, eyelid retraction and double vision.

It’s also important to control how the thyroid functions although curing the thyroid problem does not mean that complications with the orbit will also be solved as they are related but still independent processes.