Thyroid ophthalmopathy (or dysthyroid orbitopathy)

Other terms

• Dysthyroid ophthalmopathy
• Thyroid eye disease

Definition

Thyroid ophthalmopathy, which more often affects women than men, refers to the various ophthalmological disorders encountered in the case of thyroid diseases linked to autoimmune disorders. When the immune system attacks the thyroid, the tissues of the eye socket may also be affected. In this case, oedema affecting the adipose and muscular components of the orbit occurs, along with lympho-monocytic infiltration and contracture of the extra-ocular muscles, leading to reduced eye mobility. Tissue volume (fat and muscle) increases, causing exophthalmos (the eyeball protruding from the orbit) and, in severe cases, compression of the optic nerve, which can lead to permanent damage.

Causes

In most cases, thyroid ophthalmopathy is linked to excessively high levels of thyroid hormone, known as hyperthyroidism, but in 10% of cases it can also be linked to excessively low hormone levels, known as hypothyroidism. In 85-90% of cases, Graves' disease is linked to the onset of this condition.

The only risk factor is smoking, which appears to increase the risk of complications and recurrences.

Symptoms

Various symptoms may suggest thyroid ophthalmopathy, but the initial signs are mainly redness of the eyelids and conjunctiva and dryness of the eyes. Later, when the ocular tissues become inflamed, the following may also be noticed:

Palpebral signs such as retraction of the upper eyelid and downward oculo-palpebral asynergy (the upper eyelid is unable to follow the movement of the eyeball correctly)
Exophthalmos (usually bilateral and asymmetric)
Oedema
Diplopia (double vision)
Corneal damage of various grades (keratitis, ulcer, corneal perforation)
Rarely, neuropathy due to compression of the optic nerve, resulting in reduced vision or even blindness. This is extremely serious and requires rapid ophthalmological treatment.

Diagnosis

First of all, hyperthyroidism must be confirmed by clinical and biological signs. Thyroid ophthalmopathy is then confirmed by CT scan or nuclear magnetic resonance. These imaging examinations may reveal the presence of exophthalmos and the clinical signs of the disease.

Treatments

Firstly, medical treatment must be prescribed for dysthyroidism, either by the treating physician or by the endocrinologist. Thyroid ophthalmopathy is then treated with eye drops and ointments to lubricate the surface of the eye and improve the condition of the cornea, as well as lowering eye pressure, which is sometimes too high.

For more serious forms, where the inflammation is very severe or loss of vision occurs, various treatments can be introduced:

Intravenous corticosteroid-based anti-inflammatory treatments
Orbital radiotherapy (in cases of optic neuropathy)
Surgical treatment (when the inflammation has led to fibrosis affecting the orbital fat and muscle tissues).

In the majority of cases (2/3 of cases), the disease progresses favourably thanks to treatment of the hyperthyroidism and thyroid ophthalmopathy. However, surgery may be required if sequelae such as exophthalmos, diplopia, eyelid retraction or strabismus persist.

Prevention

There is no way to prevent thyroid ophthalmopathy, but monitoring thyroid function and providing appropriate treatment from the onset of symptoms will improve the course of the disease.

References

19_BASEDOW.indd (confkhalifa.com)

▷ Orbitopathie thyroïdienne| De quoi s'agit-il? Symptômes et traitements (barraquer.com)

Ophtalmopathie thyroïdienne | Institut de la Màcula (institutmacula.com)

Ophtalmopathie thyroïdienne: Causes et traitements ? (cliniquesaada.com)