Thyroid Eye Disease

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Introduction


This is a complex topic where there is a lot of confusion regarding terminology. Graves’ orbitopathy refers to the part of the thyroid disorder that affects the eyes and orbital contents. In the vast majority of cases (85%), this is part of Graves’ disease, which is a hyperthyroid state due to overproduction by all of the thyroid gland, resulting in excess thyroid hormone circulating in the body, and leading to changes throughout the body. The disease is much more common in women and will be more severe in smokers. The characteristic features of Graves’disease are:

  • A diffusely swollen thyroid gland – thyroid goitre
  • Feeling hot and agitated
  • Weight loss
  • Muscle wasting
  • Irregular or fast pulse and high blood pressure
  • Characteristic skin changes on the shins
  • Thyroid acropachy – clubbing of fingers 1% of cases

Diabetes and Myasthaenia gravis, a muscle weakening disorder, are more common than usual in Graves’ disease.

Graves’ orbitopathy may occur before the onset of the disease, and hence the thyroid levels may be normal; sometimes the eye disease follows the onset of the systemic disease. Less common forms of thyroid disorder, like a toxic nodule in the gland, inflammation of the gland or those in whom the hormone levels never rise, form 15% of all cases of orbitopathy.

Looked at another way 50% of those with Graves’ disease develop eye problems. Only 10% with eye problems need intervention by an ophthalmologist. Interestingly despite a lack of symptoms, when a CT scan is performed, muscle changes can be seen in over 70% of people with Graves’ disease.

The underlying disorder is caused by an immune response targeting the tissues of the orbit, resulting in swelling of the eye muscles, and inflammation of the orbital tissues, which become swollen, inflamed and waterlogged. This active “wet” phase is followed by an inactive or scarring phase. All the eye problems occur as a result of these two phases.

Graves’ orbitopathy signs and symptoms

Early Wet phase:

These pictures demonstrate the proptosis (eye bulging forward) and tissue inflammation and swelling affecting the eyeball and eyelids – generally this active phase is the time for management with medications.

Soft tissue changes lead to swelling and redness. The swelling behind the eyes, pushes them forward (proptosis), which also contributes to lid retraction where more of the white of the eye is visible. There is frequently an orbital ache, worse on eye movement during the active phase.

As a result of the proptosis, the cornea (front window of the eye) is exposed, leading to surface changes such as drying, more discomfort and the risk of corneal infection. In severe cases the cornea can perforate.

Vision can be blurred by refractive changes due to compression of the eyeball. Glasses can usually correct this whilst it lasts.

The muscles behind the eye swell in a characteristic way, contributing to the proptosis, but also restricting the muscle movement so that diplopia – double vision- occurs.

The swelling in the orbit can lead to compression of the optic nerve, which can lead to blindness in severe cases. The nerve swelling is not always proportionate to the visible degree of inflammation. It is related to the degree of restriction of the tissues. You may perceive a loss of brightness and loss of colour vision, with a washed out appearance to the vision.

Inactive scarring phase:

Once the active immune phase has settled there is significant scarring (fibrosis) of the involved tissues. This makes the lid retraction worse and the double vision may worsen as the muscles become more restricted.

Courtesy Chris Barry

Note that there is no inflammation or lid swelling.

How the disease is managed

  • First and foremost smoking must cease. This is the strongest modifying behavior. Put quite simply, smoking is madness with this disease.

  • This disease is best managed by a multi disciplinary team, which includes an ophthalmologist and an endocrinologist.
  • Following investigations, the thyroid gland may be treated with suppressing drugs such as carbimazole, followed with radioactive iodine to “switch off” the gland. Sometimes steroids will be given at the same time to prevent exacerbation of the eye disease.
  • Sometimes the thyroid gland is surgically removed.
  • Thyroid replacement therapy will usually be commenced. It is important to prevent a drop in circulating thyroid hormone (hypothyroidism) as this has been shown to worsen the orbitopathy. Similarly the hyperthyroid state needs to be controlled due to deleterious effects on the eye disease.

Eye/Orbit management

  • The aim is to settle the inflammation down and hasten the onset of the inactive scarring phase; the quicker this is achieved the less scarring there will be.
  • If the eye problems are only mild, simple measures such as lubricating drops and ointment may suffice.
  • If there is much more in the way of inflammation, a CT scan will be taken to assess the muscles, and get a feel for the amount of swelling in the orbit. Steroid tablets may be commenced in order to dampen down the immune response. In more severe cases – such as optic nerve involvement – high-dose intravenous steroids may be administered.
  • Sometimes low dose orbital radiotherapy is used to help dampen down the immune response and spare the use of steroid.
  • Rituximab is an immunoglobulin administered intravenously periodically. It shows great promise for many patients. Additionally low dose selenium is thought to be helpful. Both these compounds are at the investigative phase.
  • If there is no response, and vision is threatened, sometimes an emergency orbital decompression is required during the active stage of the disease to prevent optic nerve blindness.

Inactive phase


Once this phase has been reached and things have been stable for many months, a surgical rehabilitation phase can be planned.

  • Generally the first thing to consider is orbital decompression. The boney walls are removed, allowing the tissues to decompress, which allows the eyes to settle back to a more usual position.

The boney orbital walls can be removed endoscopically through the nose for less severe cases.

  • Lowering the lids can reverse lid retraction. Sometimes lid spacers can be inserted. BOTOX® has been used successfully to temporarily lower the lid in both the active and passive phases.

  • Muscle surgery can be performed to alleviate diplopia and give a better field of binocular (single) vision.

It is important to mention that it is only about 5% of all Graves’ sufferers who have the severe manifestations of the disease requiring extensive surgery and intervention.

You will see from this that it is a long and difficult journey. You will need lots of fortitude and support through all of this.


FREQUENTLY ASKED QUESTIONS

Q – How long is the disease active?
A – Typically several months to 18+ months.

Q – Does the disease burn out i.e. stop being active and progressive?
A – Yes typically it does.

Q – Can it flare up again?
A – Very unlikely.

Q – Will my appearance return to normal?
A – In most cases a good cosmetic result can be achieved with immunosuppressive therapy followed by surgery where necessary.  I would be happy to show you photographs of outcomes

Here are some support networks that you may find helpful:

www.thyroid.org.au
www.thyroideyedisease.weebly.com