Overcoming diagnostic difficulties in thyroid eye disease

October 17, 2005

When diplopia arises within the context of Graves? ophthalmopathy, the diagnosis is usually straightforward. However, the diagnosis becomes more complicated in the absence of previous thyroid dysfunction, when the patient has a remote history of hyperthyroidism, and when ocular symptoms present first, James Garrity, MD, explained Monday at the American Academy of Ophthalmology annual meeting.

Chicago-When diplopia arises within the context of Graves’ ophthalmopathy, the diagnosis is usually straightforward. However, the diagnosis becomes more complicated in the absence of previous thyroid dysfunction, when the patient has a remote history of hyperthyroidism, and when ocular symptoms present first, James Garrity, MD, explained Monday at the American Academy of Ophthalmology annual meeting.

“Fortunately, most patients present with ocular symptoms and hyperthyroidism at the same time; but there are outliers who present with thyroid symptoms first or who present with eye symptoms first,” said Dr. Garrity. He is from the Mayo Clinic, Rochester, MN.

He recounted the case of a patient who had 50 years between the diagnosis of thyroid dysfunction and the onset of ocular symptoms.

A study that determined the clinical features of patients with Graves’ ophthalmopathy found that 91% of all patients had lid signs during follow-up. At diagnosis, 71% had lid retraction and 43% had lid lag, pointing out the importance of lid signs in the evaluation of diplopia associated with Graves’ disease, Dr. Garrity emphasized.

There is also the small chance that these patients may have myasthenia gravis-about 5% of those with myasthenia have Graves’ disease and 0.5% of patients with Graves’ disease have myasthenia.

Exotropia in the presence of thyroid disease should send up a red flag, Dr. Garrity noted. “This is myasthenia gravis until proven otherwise,” he stated.

Lymphoma can be a masquerade diagnosis, as Dr. Garrity demonstrated in a patient diagnosed with steroid-dependent Graves’ ophthalmopathy. On evaluation, the patient had exotropia and no history of thyroid dysfunction.  Biopsy of the lateral rectus muscle showed lymphoma.

“The causes of diplopia with thyroid disease are usually straightforward. Forced ductions are usually restricted. Imaging studies, if needed, usually show enlarged extraocular muscles. However, if the morphology and the pattern are not consistent with thyroid disease, a biopsy should be performed to rule out lymphoma or metastasis. Myasthenia gravis is a consideration. Eye lid signs should be carefully sought,” Dr. Garrity advised.