Structural orbitopathy: a complex autoimmune disease

Structural orbitopathy (BO) is not rare as it affects 1.9% of women (and 0.16% of men). Autoimmune damage targets TSH receptors in the thyroid gland where it causes an overall hyperthyroidism, but also acts in orbital fibroblasts, thus damage to the oculomotor muscles and orbital fat. It can also affect pretibial tissues, with pretibial myxedema.

Graves’ disease (MB) is associated with orbital intervention in half of patients, but this can sometimes go unnoticed if not systematically pursued. However, in 5% of typical OB, no thyroid autoimmune process is found. In 95% of cases of orbital thyroidopathy, nine out of ten patients have hyperthyroidism and one person has Hashimoto’s disease with hypothyroidism.

In 40% of cases, OB is contemporaneous with thyrotoxicosis – within 6 months before or after – in 20% of cases preceding it, and in 35% of cases it occurs after more than 6 months.

The harmful role of tobacco

OB is bilateral in 90% of cases but is often asymmetric (a unilateral attack should rule out another cause). In practice, it is systematically accompanied by eyelid retraction. Exophthalmos is present in approximately 70% of cases. It may be associated with signs of inflammation – edema and / or redness of the eyelid, conjunctival hyperemia, conjunctival edema, damage to the gums and the fold in the inner corner of the eye.

Severe OBs account for 5% of MBs. It is more common in smokers and men. Other factors that favor OB severity are age, anti-TSH antibodies, diabetes mellitus, dyslipidemia, iatrogenic hypothyroidism, and treatment.

Rare but serious complications

The lack of eyelid coverage leads to frequent damage to the ocular surface: punctate keratitis, photophobia, foreign body sensation, blepharitis, blepharitis, which can become chronic, even corneal ulcers.

Diplopia is not compatible with regulated muscle damage but with inflammatory damage and fibrosis. Its evaluation is more complex as both eyes are often affected. There is no need to prescribe rehabilitation.

An extremely rare acute complication, subluxation of the eyeball. Finally, optic nerve compression (5% of OB) associated with increased muscle volume is difficult to diagnose, with a risk of irreversible lesion in the absence of treatment.

Balancing thyroid function without overtreatment

Imaging (computed tomography or magnetic resonance imaging) is indicated only in moderate to severe forms, if the diagnosis is suspected or optic nerve damage is suspected.

“In any case, it is necessary to protect the ocular surface, stop smoking and restore the state of the thyroid gland, which improves the OB in 65% of cases, provided that the transition to hypothyroidism, which leads to an exacerbation of the OB, is avoided,” Recalls Dr. Laurence de Pasquier, endocrinologist (Paris). Synthetic antithyroid drugs are prescribed as first-line; Radioactive iodine, in 15-33% of cases, can lead to the onset or exacerbation of steatohepatitis, especially if other dangerous factors are present.

Corticosteroid therapy is necessary in the case of orbital inflammation. Goiter surgery is sensitive because it is hypervascular. It should be avoided in the active phase of orbital damage.

Session: “Constructive Orbital Therapy”

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