Thyroid Eye Disease

What is thyroid eye disease?

Other names of thyroid eye disease (TED) are Graves' ophthalmopathy (GO), Graves' orbitopathy (GO), thyroid associated orbitopathy (TAO). Thyroid eye disease is an orbital disease and is most commonly associated with a disorder of the thyroid gland, hyperthyroidism. It is an auto-immune eye condition. It can sometimes occur in patients who have no thyroid dysfunction, or patients who have thyroid hypo-function. Most patients with thyroid diseases do not develop thyroid eye disease or, if they do, it is only mild. A small proportion develop thyroid eye disease, which may go on to require treatment either with eye drops or surgery.

Risk factors for thyroid eye disease include smoking, which results in a more severe form of the disease.

What are the signs and symptoms of thyroid eye disease?

Staring appearance with upper and lower eyelid retraction, resulting in more white of the eye being apparent.
Bulging or proptotic eyes, where the eyes protrude forwards and look very big.
Peri-ocular swelling, with puffiness of the eyelids, sub-brow area and peri-ocular region.
Orbital ache, particularly on eye movements.
Double vision (diplopia), either looking straight ahead, or on extremes of gaze.
Bloodshot appearance to the eyes associated with one or more of the above.
Reduced vision, particularly for colour vision, if the optic nerve is compressed.

Etiology:

Thyroid eye disease is an auto-immune disorder, in which there is a reaction within the orbit which results in local inflammation, swelling and fibrosis of structures in the orbit, including the fat around the eye ball and the muscles that move the eyes.

What is active thyroid eye disease?

Thyroid eye disease has well recognised stages. There is an early active phase, in which there is inflammation, and usually this can last between 3 and 12 months before beginning to stabilise and become inactive. During the active phase maximal symptoms will develop, with eyelid retraction, eye protrusion, possible double vision and redness. If the active thyroid eye disease is treated early enough, it may be possible to reduce the severity of the disease and need for surgery. It is important to stop smoking and to have good control of the thyroid hormones, so that they are in the normal range and there is no over-action, or under-action, of the thyroid gland.

How is thyroid eye disease managed?

Treatment is aimed at improving the symptoms of the orbital involvement.

Mild thyroid eye disease:

Patients with mild involvement, such as irritation, foreign body sensation and only a very small amount of protrusion of the eyes (proptosis) and no double vision, may just require reassurance, artificial tears during the day and lubricant ointment at night. If the eyelids do not close fully at night, the eyelids can be taped, to protect the surface of the eye.

Moderate thyroid eye disease:

If there is more marked eyelid malposition, with retraction and proptosis, difficulty closing the eyes and corneal problems, surgery may be required.

How is the condition managed?

The oculoplastic surgeon will monitor the colour vision, eyelid measurements, degree of proptosis, examine the surface of the eye and behind the eye, look at the optic nerve and do special radiological investigations, as required.

Severe thyroid eye disease:

Lid and orbital surgery may be required.

The principle of management is:

Medical control of thyroid gland and thyroid hormone, so that the patient is not hyper or hypothyroid.
Treatment of active thyroid eye disease if moderately severe, or severe, with tablets, such as steroids and other immuno-suppression drugs, +/- low dose orbital radiotherapy.
Surgical rehabilitation in the acute phase, or stable phase.

What type of surgery is available for thyroid eye disease?

In the acute phase, if there is optic nerve compression with the vision being affected, or there is severe exposure of the front of the eye because of such severe eyelid retraction and eye protrusion (proptosis), urgent surgery may be required to decompress the orbit and retain vision. Some younger patients who have healthy, tight tissue may have reduction of vision from optic nerve compression, but not have particularly protruding eyes, and this group must be recognised and urgent medical treatment, and/or decompression, carried out to preserve the nerve function.

Stable thyroid eye disease – rehabilitation of thyroid eye disease:

Once the patient has overcome the acute phase, the oculoplastic surgeon will do rehabilitative surgery. The goal of rehabilitative surgery is to:

Restore normal function to the orbit and eyelids.
Restore normal comfort.
Restore normal cosmesis and symmetry.

There are several operations available for rehabilitation of thyroid eye disease.

1. Orbital Decompression.

Orbital decompression is surgery to reduce the protrusion, or proptosis, of the eyes by making the orbits larger internally by creating openings into the adjacent air cells (air sinuses). This is done by an oculoplastic orbital surgeon through a small eyelid incision at the outer corner of the eye, with most of the incision hidden on the inside of the lower eyelid. Sometimes an additional approach is done through the inside of the nose, in order to open up into the medial, or ethmoid, sinus, in preference to opening that sinus via the eyelid. A balanced decompression is aimed for, in which the orbit is widened horizontally, thus reducing the risk of causing double vision. This is the same operation that is done in the acute phase if there is an optic nerve compression, in which the pressure, or tension, on the optic nerve is reduced by increasing the internal size of the orbit by operating surgically on the bony walls of the orbit.

2. Eye Muscle Surgery

If there is a squint (strabismus) with double vision and the eyes cannot be easily corrected with small prisms, eye muscle surgery, or strabismus surgery is necessary. The oculoplastic surgeon waits until the double vision, or eye motility, is completely stable before carrying out eye muscle surgery. The aim of this surgery is to restore a good field of binocular i.e. two eyes seeing together of single vision, when both eyes look straight ahead and in the reading position. Squint surgery may not completely remove all double vision and the patient may still notice some double vision in extremes of gaze. Squint surgery is usually done under general anaesthetic and may involve an adjustable stitch on the eye muscle, which is then locally adjusted with the patient awake a few hours after surgery to give the best possible single vision.

3. Eyelid Retraction.

If the upper eyelids are too high, or the lower eyelids too low, resulting in white of the eye appearing either above or below the coloured iris and difficulty in closing the eyes, eyelid surgery can be done to correct the eyelid position. The upper eyelid is lowered, or the lower eyelid raised, the latter sometimes requiring a small spacer using placement of tissue from the patient's roof of mouth, for instance, to help restore the normal position of the eyelids and eyelid closure.

4. Further Eyelid Surgery - Blepharoplasty & Peri-Ocular Surgery.

Debulking of peri-ocular puffiness may be required by upper eyelid and sub-brow removal of fatty tissue and lower eyelid removal of fatty tissue. Further treatment can also be done to the lower eyelid skin, to tighten it where it has been swollen by the thyroid eye disease. This is known as blepharoplasty, and is done as part of rehabilitative surgery for patients with thyroid eye disease.

Lid and orbital surgery may be required.

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Thyroid Eye Disease