Thyroid Eye Disease (also: thyroid ophthalmopathy, dysthyroid eye disease, Graves' disease)

What's going on?

In autoimmune thyroid disease (Graves' disease), pathological antibodies attack the thyroid tissue, causing an initial overstimulation of thyroid hormone production. These antibodies also cross-react with antigen found on cells within the orbit. This leads to an autoimmune inflammatory reaction involving all the orbital structures.

The accumulation of inflammatory cells and by-products results in significant increase in orbital volume and proptosis. Proptosis due to thyroid eye disease is called exophthalmos.

There are two phases: the initial active phase and the long-standing, quiescent phase. In the active phase, the eye is red and inflamed, with the potential for significant optic nerve-threatening proptosis. Once this phase has settled, the patient is left with the consequences of the severe inflammation and scarring.

Often the globe fails to return to its original position but remains proptosed (see above). The extraocular muscles, which are usually involved in the inflammatory process, become fibrosed and do not function, resulting in a squint with double vision. The upper and lower lids are often retracted, due to being forced further apart by the forward displacement of the globe. Scarring and sympathetic hyperstimulation may worsen this lid retraction. The quiescent phase is dominated by oculomotility disturbance, proptosis, lid retraction, corneal drying and poor cosmesis. Often cosmesis is a major concern, particularly as this disease can affect young females.

Thyroid eye disease may occur before, during or even long after the onset of frank thyroid disease.

If I examine the patient, what will I find?

If this is the active phase, the eye(s) will be proptosed and red, and the conjunctiva may be ballooned up, creating a jelly-like appearance called chemosis. Also, eye movement may be disturbed and the pupils may react abnormally (RAPD). Visual acuity and colour vision may be reduced in one or both eyes. The lids will be retracted, with scleral show superiorly and inferiorly. The eyes are often described as having a staring appearance.

What if I've diagnosed it?

If you suspect the patient has thyroid eye disease, it is worth doing thyroid function tests and referring to the hospital eye service. The urgency will depend on the severity of symptoms. If the patient's eyes are obviously proptosed then a referral soon via casualty is warranted. If the patient's vision is compromised, then urgent/immediate referral is warranted for rapid assessment of optic nerve integrity.

What will the hospital do?

Once the diagnosis is made, the patient's thyroid function will be assessed and referral made to an endocrinologist, if appropriate.
If the optic nerve is compromised, the patient will require decompression, either medically or surgically. Medical decompression relies on immune-mediation to reduce the inflammatory reaction within the orbit. This is usually done with high-dose, pulsed corticosteroids. Surgical decompression involves breaking up to four of the orbital walls, allowing the orbital contents to prolapse into the sinuses and thus reducing retro-orbital pressure and proptosis. The number of orbital walls involved depends upon the severity of the proptosis.

Even if the optic nerve is not compromised, early intervention with high-dose corticosteroids may reduce the risk of sight-threatening complications and may indeed reduce the residual problems in the quiescent phase.

What do I need to do?

Certainly the patient's thyroid status needs to be assessed and thyroid function optimised. Stop the patient smoking (easier said than done!).

What to tell the patient

They have a problem affecting their eyes that is often linked to an autoimmune thyroid disorder. Tell them about the active and quiescent phases, and that future problems may occur. Advise smokers strongly to give up, as smokers have a much worse prognosis for final outcome.

Problems that may arise and how to deal with them

Corneal exposure remains a concern, so if the patient has significant proptosis or is symptomatic with a red or irritable eye, they should be given topical, artificial teardrops. Watch out for progressive proptosis and visual compromise. Loss or disturbance of colour vision is an early feature of optic nerve compromise and may be assessed with Ishihara test plates.

Patients who have significant cosmetic problems related to their eye disease may warrant surgical rehabilitative intervention.